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  1. 1. April 2016designworldonline.com motioncontroltips.com Transmission REFERENCE GUIDE POWER Cover.indd 1 5/2/16 11:24 AM
  2. 2. Our wide range of products gives you maximum design freedom. As the leader in linear motion, THK is dedicated to developing not just the best choices, but also the most choices in linear motion solutions. Our virtually limitless range of products includes linear motion guides, ball screws, actuators, specialty products and more - many featuring our patented Caged Technology. To learn more, give us a call at 1-800-763-5459 or visit www.thk.com. 84014203 THKProdLineAd(DW)_840-06205 GN-N Ad(MSD) 12/23/14 2:35 PM Page 1 THK_PTGuide4-16.indd 1 4/29/16 9:53 AM
  3. 3. Whatever keeps you up at night, we’ve got a solution—the largest selection of motors, pumps and air-moving devices available. Plus, one-of-a-kind solutions ready to be custom-engineered for your precision industrial, commercial, combustion or transportation application. If you can dream it, you’ll find it at Solution City. FOR MOTION CONTROL INNOVATION, SOLUTION CITY NEVER SLEEPS. © 2015 by AMETEK Inc. All rights reserved. 100 East Erie Street Kent, OH 44240 ametekdfs.com AMETEKPMC 18611_City Never Sleeps Ad_9x10.875.indd 1 7/29/15 9:14 AMAMETEK PMC (Solutions City) 8-15 (NEW).indd 1 4/29/16 9:56 AM
  4. 4. promessinc.com 810-229-9334 Providing solutions to the industry since 1984 “Cloning the Perfect Part” WHY?WHY? Still putting science projects on your floor? Still putting science projects on your floor? Promess provides you with a COMPLETE system to help make YOUR life easier. Don’t guess what you need, let Promess help you. Call us today to set up a visit to our Process Development Center EMAP REMAP TorquePRO Promess_PTGuide4-16.indd 2 4/29/16 9:58 AM
  5. 5. HaydonKerk LinearActuators... 1500 Meriden Road Waterbury,CT 06705 U.S.A. Telephone: 203 756 7441 SOLUTIONSINMOTION ® Haydon Kerk Motion Solutions hybrid and can-stack linear actuators continue to offer equipment designers new motion control solutions that provide unmatched performance-to-size ratios, patented technologies and thousands of configuration options, and a vast experience in customized solutions. HYBRID actuators are available in six sizes from Size 8: 21 mm2 (0.8 -in.) to Size 34: 87 mm2 (3.4-in.) – capable of delivering up to 500 pounds (2224 N) of force. Travels per step range from .001524 mm (.00006-in) to .127 mm (.005-in), with micro stepping capability for even finer resolution. An integrated, programmable IDEA™ Drive is also available for Size 17 hybrids. The G4 Series represents the industry’s most robust and most powerful CAN-STACK linear actuators. The G4 Series offers diameters of 20 mm (.79-in), 26 mm (1-in), and 36 mm (1.4-in). The can-stack product line also includes motors with diameters of 15 mm (0.59-in), 20 mm (.79-in) , 26 mm (1-in), 36 mm (1.4-in) and Ø 46 mm (1.8-in), available with captive, non-captive or external linear lead-screws. Haydon Kerk Motion Solutions continues to be an innovative motion control technology company with a global network of people, facilities and services dedicated to engineering and manufacturing the world’s most advanced linear motion solutions. For more information: www.HaydonKerk.com > Linear Actuators Size 17 - 43 mm2 (1.7-in)2 non-captive hybrid linear actuator with programmable IDEA™ stepper motor drive High performance, precision linear motion technology 25000 Series G4, can-stack captive, non-captive, external linear actuator steppers 25 mm (1.0-in) diameter Size 8 - 21 mm2 (0.8-in)2 captive hybrid linear actuator stepper motor. Also available in Single and Double Stack, non-captive and external linear. Size 34 - 87 mm2 (3.4-in)2 captive hybrid linear actuator stepper motor. Non-captive and external linear also available. Size 17 - 43 mm2 (1.7-in)2 Double Stack - external, non-captive, captive hybrid linear actuator stepper motors Call 1 8OO 243 2715 www.HaydonKerk.com Haydon Kerk 4-16.indd 3 4/29/16 9:59 AM
  6. 6. 4 DESIGN WORLD 4 • 2016 www.designworldonline.com PowerTransmission REFERENCEGUIDE MOTION designs continually evolve, but will always rely on mechanical devices, particularly where the drive of an electric motor engages a load to execute machine tasks. In fact, as the technical reviews in this 2016 Power Transmission Reference Guide explain, applications for mechanical motion components only proliferate as technical innovations make them increasingly effective. Consider this Reference Guide’s section on bearings by Associate Editor Mike Santora. The most common bearing applications are in heavy machinery and industrial setups as always, but renewable- energy use is spurring innovations to get higher capacities as turbines push the limits of bearing designs. There’s also increased demand for complete system solutions over components, which is changing the POWER-TRANSMISSION COMPONENTS ARE MAINSTAYS POWER-TRANSMISSION COMPONENTS ARE MAINSTAYS design of linear systems, actuators and gearmotors, as well as subsystems such as conveyors and robotics. Consider the section on gearmotors in this Reference Guide by Senior Editor Miles Budimir. Here, manufacturers are predesigning and assembling more motors than ever with gearboxes upfront, for an ever-expanding array of ac gearmotors and servo gearmotors. Such gearmotors are increasingly accurate as well, particularly those sporting planetary gearsets. That’s thanks in part to how manufacturers are making gearing with the latest approaches in design, machining and assembly. Check out the sections in this Reference Guide covering gear-design consultation, custom gear designs and analysis, as well as general speed reducers, worm gearing, and shaft-mount sets. These articles detail common and custom offerings that optimize inertia matching and speed output. In fact, today’s software now lets designers get design-specific gearing—and other power- transmission components—at lower cost than that of general-purpose offerings from just a decade ago. In fact, today’s moving designs rely on an increasingly diverse array of mechanical components to protect expensive subsystems and change motion-system dynamics to simplify programming. These actuators, ballscrews, bearings, brakes, chains, collars, couplings, gearing, rails and rack-and-pinion sets transmit power in ways that get higher performance than ever. LISA EITEL SENIOR EDITOR @DW_LISAEITEL DW half p Editorial_PTGuide_V3.LE.MD.indd 4 4/29/16 10:20 AM
  7. 7. WWW.MOTIONCONTROLTIPS.COM WEBINAR ALERT DOWNLOAD ON DEMAND: TRENDS TO WATCH IN MOTION CONTROL bit.ly/1Lxaexl So use this Reference Guide as a review of basic component functions or as an update on what’s new in power-transmission designs—and to get instructions on how to make the most of proliferating features to meet evolving motion-system requirements. As mechanical designs change, count on us Design World editors to bring you technology updates to help you specify and integrate the right components. We invite your feedback and requests for technical information. There are innumerable ways to reach us: Email me at leitel@wtwhmedia.com or tweet to @DW_LisaEitel, @Linear_Motion and @Motion_Control. Connect with our Design World Network Facebook page at facebook.com/DesignWorldNetwork, and let us know what designs you’re using or are looking to apply. Also look out for the 2016 Motion Systems Handbook and 2016 Motion Casebook coming to you in August and November for complete coverage of electronic and programming technologies for motion designs, as well as real-world application examples and illustrations to inform your next build. In the mean time, also find all our motion-technology news announcements (as well as technical archives) on our motion tips sites—motioncontroltips. com, linearmotiontips.com, sensortips.com, bearingtips.com and couplingtips.com. Get a Free Power Basics Poster teledynelecroy.com/motor-drive-analyzer | teledynelecroy.com/contactus © 2015 Teledyne LeCroy, Inc. All rights reserved. Line Voltage, Current, and Power – The Basics THREE-PHASE LINE VOLTAGE Single-phase line voltage consists of one voltage vector with: • Magnitude (voltage) • Angle (phase) Typically, the single-phase is referred to as “Line” voltage, and is referenced to neutral. Neutral Line The single-phase voltage vector rotates at a given frequency • Typically, 50 or 60 Hz for utility-supplied voltage At any given moment in time, the voltage magnitude is V * sin(α) • V = magnitude of voltage vector • α = angle of rotation, in radians The resulting time-varying “rotating” voltage vector appears as a sinusoidal waveform with a fixed frequency • 50 Hz in Europe • 60 Hz in US • Either 50 or 60 Hz in Asia • Other frequencies are sometimes used in non-utility supplied power, e.g. • 400 Hz • 25 Hz SINGLE-PHASE Three-phase line voltage consists of three voltage vectors. • By definition, the system is “balanced” • Vectors are separated by 120° • Vectors are of equal magnitude • Sum of all three voltages = 0 V at Neutral Typically, the three phases are referred to as A, B, and C, but other conventions are also used: • 1, 2, and 3 • L1, L2, and L3 • R, S, and T The three voltage vectors rotate at a given frequency • Typically, 50 or 60 Hz for utility-supplied voltage The resulting time-varying “rotating” voltage vectors appear as three sinusoidal waveforms • Separated by 120° • Of equal peak amplitude Voltage value = VX*sin(α) • VX = magnitude of phase voltage vector • α = angle of rotation, in radians VA-B VA-N 120° VA VB VC Neutral A B C ω (rad/s) or freq (Hz) 120° 120° 120° Neutral Neutral Line ω (rad/s) or freq (Hz) 200 Time AC Single-Phase “Utility” Voltage 120VAC Volts(Peak),Line-Neutral 150 100 50 0 -50 -100 -150 -200 120 VAC Example 800 Time AC Three-Phase “Utility” Voltage 480VAC , Measured Line-Line Volts(Peak),Line-Line 600 400 200 A-B Voltage B-C Voltage C-A Voltage 0 -200 -400 -600 -800 480 VAC Example 800 Time AC Three-Phase “Utility” Voltage 480VAC , Measured Line-Neutral Volts(Peak),Line-Neutral 600 400 200 A-N Voltage B-N Voltage C-N Voltage Three-phase Rectified DC 0 -200 -400 -600 -800 480 VAC Example Line-Line Voltage Measurements Line-Neutral Voltage Measurements Important to Know • Voltage is stated as “VAC”, but this is really VRMS • Rated Voltage is Line-Neutral • VPEAK = 2 * VAC (or 2 * VRMS ) • 169.7 V in the example below • VPK-PK = 2 * VPEAK • If rectified and filtered • VDC = 2 * VAC = VPEAK Voltages can be measured two ways: • Line-Line (L-L) • Also referred to as Phase-Phase • e.g. from VA to VB, or VA-B • Line-Neutral (L-N) • Neutral must be present and accessible • e.g. from VA to Neutral, or VA-N • VL-L conversion to VL-N • Magnitude: VL-N * 3 = VL-L • Phase: VL-N - 30° = VL-L Important to Know • Voltage is stated as “VAC”, but this is really VRMS • Rated Three-phase voltage is always Line-Line (VL-L) • Line-Line is A-B (VA-B), B-C (VB-C), and C-A (VC-A) • Line-Line is sometimes referred to as Phase-Phase • VPEAK(L-L) = 2 * VL-L • 679 V in the example to the right • VPK-PK(L-L) = 2 * VPEAK(L-L) If a neutral wire is present, three-phase voltages may also be measured Line-Neutral • VL-N = VL-L/ 3 • 277 VAC (VRMS) in this example • VPEAK = 2 * VL-N • 392 V in the example to the right • VPK-PK = 2 * VPEAK If all three phases are rectified and filtered • VDC = 2 * VL-N * 3 = VPEAK * 3 = 679 V in the example to the right LINE CURRENT Like voltage, the single-phase current vector rotates at a given frequency • Typically, 50 or 60 Hz At any given moment in time, the current magnitude is I*sin(α) • I = magnitude of current vector • α = angle of rotation, in radians The resulting time-varying “rotating” current vector appears as a sinusoidal waveform Like voltage, the resulting time-varying “rotating” current vectors appear as three sinusoidal waveforms • Separated by 120° • Of equal peak amplitude for a balanced load Current value = IX*sin(α) • IX = magnitude of line current vector • α = angle of rotation, in radians Neutral Line freq (Hz) By definition, the system is “balanced” • Vectors are separated by 120˚ • Vectors are of equal magnitude • Sum of all three currents = O A at neutral (provided there is no leakage of current to ground) Like voltage, three-phase current has three different line current vectors that rotate at a given frequency • Typically, 50 or 60 Hz for utility-supplied voltage SINGLE-PHASE THREE-PHASE A B C ω (rad/s) or freq (Hz) 120° 120° 120° Neutral Line Current Measurements 10 ARMS Example Important to Know • Current is stated as “lAC”, but this is really IRMS • Line currents can represent either current through a coil, or current into a terminal (see image below) depending on the three-phase winding connection • IPEAK = 2 * IRMS • 14.14A for a 10 ARMS current in the example to the right • IPK-PK = 2 * IPEAK -15 -12 -9 -6 -3 0 3 6 9 12 15 LineCurrent(Peak) Time AC Three-Phase "Line" Currents A Current B Current C Current IC IA IB A B C N A B C IC IA IB LINE POWER SINGLE-PHASE Electric Power • “The rate at which energy is transferred to a circuit” • Units = Watts (one Joule/second) For purely resistive loads • P = I2R = V2/R = V * I • The current vector and voltage vector are in perfect phase I Inductive load V P ≠ V * I φ N I Capacitive load P ≠ V * I V φ N Real Power ImaginaryPower S P Q φ φ φ φ QB QC QA SB SA SC PB PA PC Phase Angle (φ) • Indicates the angular difference between the current and voltage vectors • Degrees: - 90° to +90° • Or radians: -π/2 to + π/2 For capacitive and inductive loads • P ≠ V * I since voltage and current are not in phase • For inductive loads • The current vector “lags” the voltage vector angle φ • Purely inductive load has angle φ = 90° • Capacitive Loads • The current vector “leads” the voltage vector by angle φ • Purely capacitive load has angle φ = 90° THREE-PHASE For purely resistive loads • PA = VA-N * IA • PB = VB-N * IB • PC = VC-N * IC • PTOTAL = PA + PB + PC As with the single-phase case, Power is not the simple multiplication of voltage and current magnitudes, and subsequent summation for all three phases. Apparent Power for each Phase • |S|, in Volt-Amperes, or VA • = VRMS * IRMS for a given power cycle Real Power for each Phase • P, in Watts • = instantaneous V * I for a given power cycle Voltage is measured L-L • Neutral point may not be accessible, or • L-L voltage sensing may be preferred Current is measured L-N L-L voltages must be transformed to L-N reference: Calculations are straightforward, as described above: • PTOTAL= PA + PB + PC • STOTAL = SA + SB + SC • QTOTAL = QA + QB + QC Voltage is measured L-L on two phases • Note that the both voltages are measured with reference to C phase Current is measured on two phases • The two that flow into the C phase Mathematical assumptions: • Σ(IA + IB + IC) = 0 • Σ(VA-B + VB-C + VC-A) = 0 This is a widely used and valid method for a balanced three-phase system VB-C VA-C IA IB A B C N A B C VB-C VA-C IA IB Single-phase, Non-resistive Loads Phase Angle Single-phase Real, Apparent and Reactive Power Three-phase, Resistive Loads Three-phase, Non-resistive Loads Two Wattmeter Method – 2 Voltages, 2 Currents with Wye (Y or Star) or Delta (∆) Winding VB-N VA-N VC-N IC IA IB A B C N VA-B VB-C VC-A IC IA IB A B C N Power Factor (PF, or λ) • cos(φ) for purely sinusoidal waveforms • Unitless, 0 to 1, • 1 = V and I in phase, purely resistive load • 0 = 90° out of phase, purely capacitive or purely inductive load • Not typically “signed” – current either leads (capacitive load) or lags (inductive load) the voltage Voltage Current Note: Any distortion present on the Line voltage and current waveforms will result in power measurement errors if real power (P) is calculated as |S|*cos(φ). To avoid measurement errors, a digital sampling technique for power calculations should be used, and this technique is also valid for pure sinusoidal waveforms. Resistive load V P=V * I N I Power Factor Line-Line Voltage Sensing Case VB-N VA-N PTOTAL = VA-N * IA + VB-N * IB + VC-N * IC VC-N IB IA IC N φ VB-N VA-N PTOTAL ≠ VA-N *IA + VB-N * IB + VC-N * IC VC-N IB IAIC N Three-phase, Any Load Apparent Power • |S|, in Volt-Amperes, or VA • = VRMS * IRMS for a given power cycle Real Power • P, in Watts • = instantaneous V * I for a given power cycle Reactive Power • Q, in Volt-Amperes reactive, or VAr • Q = S2 - P2 • Does not “transfer” to load during a power cycle, just “moves around” in the circuit Reactive Power for each Phase • Q, in Volt-Amperes reactive, or VAr • Q = S2 - P2 • PTOTAL = PA + PB + PC • STOTAL = SA + SB + SC • QTOTAL = QA + QB + QC PTOTAL = VA-C * IA + VB-C * IB STOTAL= VRMSA-C * IRMSA + VRMSB-C * IRMSB QTOTAL = STOTAL 2 - PTOTAL 2 “Not True” RMS Wye (Y) 3-phase Connection • Neutral is present in the winding • But often is not accessible • Most common configuration Delta (∆) 3-phase Connection • Neutral is not present in the winding (in most cases)A B C N A B C For one power cycle • The digital samples are grouped into measurement cycles (periods) • For a given cycle index i…. • The digitally sampled voltage waveform is represented as having a set of sample points j in cycle index i • For a given cycle index i, there are Mi sample points beginning at mi and continuing through mi + Mi -1. • Voltage, current, power, etc. values are calculated on each cycle index i from 1 to N cycles. Digital Sampling Technique for Power Calculations� Period 1 Mi = 18 points Period 2 Mi = 18 points mi = point 7 mi = point 25 VPK-PK “True” RMS For one power cycle Three-Phase Winding Connections VRMS IRMS Real Power (P, in Watts) Apparent Power (S, in VA) Reactive Power (Q, in VAR) Power Factor (λ) Phase Angle (φ) VRMSi = Vj 2 Mi 1 mi + Mi - 1 Σj=mi IRMSi = Ij 2 Mi 1 mi + Mi - 1 Σj=mi Pi = Vj * Ij Mi 1 mi + Mi - 1 Σj=mi Si = VRMSi * IRMSi magnitude Qi = Si 2 - Pi 2 Sign of Qi is positive if the fundamental voltage vector leads the fundamental current vector λi = Pi Si magnitude Φi = cos-1λi Sign of Φi is positive if the fundamental voltage vector leads the fundamental current vector Formulas Used for Per-cycle Digitally Sampled Calculations VRMS = VPK-PK 2 2 1 VRMS = VAC 2 MDA800 Series Motor Drive Analyzers 8 channels, 12-bits, 1 GHz tlec-2015_power-poster-final-cmyk-HIRES.pdf 1 11/9/15 2:54 PM Learn more about the MDA800 and sign up to receive a Power Basics Poster for free: teledynelecroy.com/static-dynamic-complete Identify 3-phase electrical and motor mechanical static and dynamic power behaviors. Built on an 8 channel, 12-bit, 1 GHz oscilloscope platform for power section and embedded control debug – complete test capability. MDA800 Series Motor Drive Analyzers One Instrument, One Solution Identify 3-phase mechanical behaviors. Built on an platform for power section complete test capability. MDA800 Series Motor Drive Analyzers One Instrument, One Solution tlec-mda-poster-designworld.indd 1 2/5/16 2:04 PM Editorial_PTGuide_V3.LE.MD.indd 5 4/29/16 10:37 AM
  8. 8. PowerTransmission REFERENCEGUIDE 6 DESIGN WORLD — MOTION 4 • 2016 motioncontroltips.com | designworldonline.com VIDEO Videographer John Hansel jhansel@wtwhmedia.com @wtwh_Jhansel Videographer Kyle Johnston kjohnston@wtwhmedia.com @wtwh_Kyle Videographer Alex Barni abarni@wtwhmedia.com EDITORIAL Editorial Director Paul J. Heney pheney@wtwhmedia.com @dw_Editor Managing Editor Leslie Langnau llangnau@wtwhmedia.com @dw_3Dprinting Executive Editor Leland Teschler lteschler@wtwhmedia.com @dw_LeeTeschler Senior Editor Miles Budimir mbudimir@wtwhmedia.com @dw_Motion Senior Editor Mary Gannon mgannon@wtwhmedia.com @dw_MaryGannon Senior Editor Lisa Eitel leitel@wtwhmedia.com @dw_LisaEitel Associate Editor Mike Santora msantora@wtwhmedia.com @dw_MikeSantora Assistant Editor Michelle DiFrangia mdifrangia@wtwhmedia.com @wtwh_Michelle NEW MEDIA/WEB/ BUSINESS DEVELOPMENT Web Development Manager B. David Miyares dmiyares@wtwhmedia.com @wtwh_WebDave Web Development Specialist Patrick Amigo pamigo@wtwhmedia.com @amigo_patrick Digital Marketing Specialist Andrew Zistler azistler@wtwhmedia.com GRAPHICS Director, Creative Services Mark Rook mrook@wtwhmedia.com @wtwh_graphics Art Director Matthew Claney mclaney@wtwhmedia.com @wtwh_designer Graphic Designer Allison Washko awashko@wtwhmedia.com @wtwh_allison Traffic Manager Mary Heideloff mheideloff@wtwhmedia.com Production Associate Tracy Powers tpowers@wtwhmedia.com MARKETING Marketing Manager Stacy Combest scombest@wtwhmedia.com @wtwh_Stacy Marketing & Event Coordinator Jen Kolasky jkolasky@wtwhmedia.com @wtwh_Jen Marketing Coordinator Lexi Korsok lkorsok@wtwhmedia.com @medtech_Lexi Digital Marketing Specialist Josh Breuler jbreuler@wtwhmedia.com @wtwh_Joshb Digital Marketing Intern Aly Ryan aryan@wtwhmedia.com @wtwh_Aly Business Development Manager Patrick Curran pcurran@wtwhmedia.com @wtwhseopatrick Online Coordinator Jennifer Calhoon jcalhoon@wtwhmedia.com @wtwh_Jennifer Director, Audience Development Bruce Sprague bsprague@wtwhmedia.com Controller Brian Korsberg bkorsberg@wtwhmedia.com 2011 - 2015 2014 Winner Follow the whole team on twitter @DesignWorld CONNECT WITH US! StaffPage_PTGuide_V1.indd 6 4/29/16 5:34 PM
  9. 9. The PITTMAN Difference When evaluating DC motor choices, it’s what’s inside that matters. What’s Inside Matters® On the outside, this looks like an ordinary DC motor. In fact, this particular motor is not a standard off-the-shelf part, but designed exactly to a customer’s specific technical requirements. PITTMAN has an experienced team of engineers focused on providing the perfect motor assembly to our customers demanding motion applications. • Special brush formulation for use in a very low humidity environment • Bearing system to handle higher than normal axial loads • Very tight balancing spec to minimize audible noise and vibration at high speeds • Unique magnet charge pattern to minimize cogging at low speeds • Specially chosen surface-mount components inside the motor to meet an aggressive EMC requirement • Numerous integrated spur and planetary gearboxes, encoders, brakes and drives www.Pittman–Motors.com 343 Godshall Drive, Harleysville, PA 19438 USA: +1 267 933 2105 Europe: +33 2 40 92 87 51 Asia: +86 21 5763 1258 Pittman (AMETEK) 3-16.indd 7 4/29/16 10:00 AM
  10. 10. 8 DESIGN WORLD — MOTION 4 • 2016 motioncontroltips.com | designworldonline.com PTDA Updates ..............................................10 Actuators Electrical ..................................................14 Rigid Chain ..............................................18 Ballscrews .....................................................20 Bearings ......................................................24 Belts, Pulleys ...........................................28 Brakes, Clutches ...................................31 Cabling ................................................32 Chain, Roller, Sprocket .......................34 Compression Springs ........................38 Couplings ..........................................41 Drives ................................................50 Gearing .............................................54 Gearmotors ........................................66 Leadscrews...........................................68 Linear Motion ........................................70 Locking Devices, Shaft Collars .................75 Lubrication ..................................................78 Motors ..........................................................80 Positioning Stages ........................................84 Seals .............................................................86 Shock, Vibration Damping ............................88 MOTIONCONTROLTIPS.COM INSIDE P04Power-transmission components are mainstays VOL2 NO2 18 Cover photography by Miles Budimir Contents_PTGuide_V1.indd 8 5/3/16 10:42 AM
  11. 11. the #1 value in automation Order Today, Ships Today! *SeeourWebsitefordetailsandrestrictions. ©Copyright2014AutomationDirect,Cumming,GA USA. Allrightsreserved. 1-800-633-0405 Research, price, buy at: www.automationdirect.com/power-transmission Precision Gearboxes If it is precision you need, our SureGear family of precision gearboxes is an excellent solution. They are available in a wide range of ratios and styles, and provide high-precision motion control at an incredible price. • Servomotor gearboxes start at $398.00 • Small NEMA motor gearboxes start at $209.00 Worm Gearboxes IronHorse® worm gearboxes are built to withstand the toughest applications while delivering reliable speed reduction and increased torque output. • Aluminum gearboxes start at $88.00 • Cast Iron gearboxes start at $147.00 Affordable Power Transmission high-quality components at low prices! NEW! • Jaw / Spider Couplings start at $10.50 • Double Loop Couplings start at $34.00 • Oldham Couplings start at $14.25 • Beam-Style Servo Couplings start at $42.00 • Bore Reducers start at $7.00 Synchronous Drives Our SureMotion line of synchronous drive components provide dependable speed and torque changes without unwanted slippage and speed variations. • Drive pulleys start at $5.25 • Drive belts start at $2.00 SureMotion® Drive Couplings Reduce the unwanted stress caused by shaft misalignment with our new line of high-quality drive couplings. These drive couplings come in a variety of styles, torque ranges and coupling capabilities each designed to enhance system performance and prevent costly failures. AutomationDirect_PTGuide4-16.indd 9 4/29/16 10:32 AM
  12. 12. Power Transmission REFERENCE GUIDE 10 DESIGN WORLD — MOTION 4 • 2016 motioncontroltips.com | designworldonline.com 2016 LEADERSHIP DEVELOPMENT CONFERENCE The Power Transmission Distributors Association (PTDA) held its 2016 Leadership Development Conference in early March in the Historic District of Charleston, S.C. PTDA members continuously seek ways to bring their future management team up-to-speed so they can step into a supervisory role ready to excel. The 2016 Leadership Development Conference fulfilled that need. Designed for emerging power transmission/motion control leaders who want to enhance their management skills, network in small group settings, and learn best practices that support business results, those that participated in this year’s conference benefited from two sessions: • “Ready. Get Set. Lead”—a dinner program by Randy Disharoon, director global accounts, Rexnord Industries, on how to quickly ramp up younger leaders for success to kick-off the conference • “Businessopoly”—a full-day, interactive, team-oriented business simulation game, led by industry veteran Michael Cinquemani, president and CEO, Master Power Transmission. Cinquemani said, “We are going to really challenge people to give them a deeper understanding of their decision-making: how it affects the profit and loss statement, the balance sheet, the statement of cash flows, and then review their results compared to their initial plans.” PTDAP O W E R T R A N S M I S S I O N D I S T R I B U T O R S A S S O C I AT I O N UPDATESMIKE SANTORA • ASSOCIATE EDITOR • @DW_MIKESANTORA The PTDA Spring Governance Meetings attracted nearly 90 volunteer senior leaders to Charleston, S.C., along with more than 45 Next-Gen members who took part in the PTDA 2016 Leadership Development Conference. Attendees played Businessopoly, the name PTDA gave to an interactive, hands-on board game that teaches executive management skills. PTDAUpdates_PTGuide_V3.indd 10 4/29/16 10:38 AM
  13. 13. 11DESIGN WORLD — MOTIONmotioncontroltips.com | designworldonline.com 4 • 2016 PTDA WELCOMES SIX NEW MEMBERS PTDA has recently welcomed six new member companies. DISTRIBUTOR MEMBER MJ May Material Specialists (South Holland, Ill.) distributes mechanical PT components, bearings, motors, motor/motion control, electrical/electronic drives, material handling, hydraulics/pneumatics, and PT accessories. President Walter Lopez said, “As a small business looking to grow in the power transmission market, it was a no- brainer for us to join. The access to manufacturers and opportunity to strengthen established relationships will greatly benefit us in our quest to become a premier distributor of power transmission products.” MANUFACTURER MEMBERS Auburn Bearing & Manufacturing (Macedon, N.Y.) manufacturers bearings. “We chose to join PTDA because a vast majority of our sales are through an established network of distributors across the marketplace. PTDA will assist us in expanding that network even further,” said Peter Schroth, president. Helical Products Company, a location of MW Industries, (Rosemont, Ill.) manufactures spring couplings and retaining rings. Robert Jack, VP marketing and strategic planning, said, “The opportunity to network with both manufacturers and distributors in our industry is very valuable to us, and we look forward to being an active member and forging many new relationships in the years to come." iwis Drive Systems (Indianapolis, Ind.) manufactures chains and sprockets. “iwis joined PTDA to increase our network within the industrial distribution arena. The fact is, we have made significant investments into new products and value added services and PTDA represents a powerful tool for us to capitalize on these initiatives,” said Kody Fedorcha, VP, sales and marketing. Rosta USA Corporation (South Haven, Mich.) is a manufacturer of motor bases. Wittenstein (Bartlett, Ill.) manufactures couplings, gearing, motors, motor/motion control products and linear motion components. Tom Coyle, director of sales NA, said, “We are pleased to be a part of this association. My goals as a member of PTDA are to leverage the wide network of distributor organizations and contacts, gain access and new perspectives to industry economics and trends, and finally to increase exposure of Wittenstein,” PTDA 2016 CANADIAN CONFERENCE Registration is still open for the PTDA 2016 Canadian Conference, to be held June 9-10, 2016, at The Westin Ottawa in Ottawa, Ontario. For the 15th year, members of the Canadian power transmission/motion control (PT/MC) industry gather for business networking, market-driven education, a manufacturer industry showcase and more. Networking opportunities abound at the PTDA 2016 Canadian Conference. Participants have many opportunities to meet channel partners—both new and established—in comfortable settings such as the Industry Showcase Welcome Reception, featuring tabletop exhibits from every registered PTDA manufacturer member company. Along with networking, business market-driven education takes center stage. Participants will hear information targeted to solve the most vexing needs of the industry including information on corporate culture, hiring, knowledge transfer and an update on the Canadian mining industry. For more information about the Canadian Conference, please visit www.ptda.org/CanadianConference. Jim LaHaie, president, W.C. DuComb Co. and John Masek, SVP, Bearing Service Inc., took advantage of PTDA’s complimentary Regional Networking Events and an optional Detroit Tigers game last year. In 2016, complimentary PTDA Regional Networking Events are coming to Minneapolis, Chicago and Cincinnati and are open to any employee of a PTDA member company or a prospective member company. PTDAUpdates_PTGuide_V3.indd 11 4/29/16 10:39 AM
  14. 14. Advanced Products for Robotics and Automation. Customer Driven Innovation Design EngineeringPrototype to Product Launch From customer driven innovation to contract manufacturing, we help differentiate your product and applications. Connect with us today to explore what CGI Motion can do for you. Download our full capabilities brochure at cgimotion.com copyright©2016 cgi inc. all rights reserved. 0425CCBS CGI’s World Class Vertically Integrated Flow Processes • Design for Manufacturability - DFM • Fixturing Design and Fabrication • Prototyping Support 3-D Model Printing on-site • Process controls designed and implemented • Process development for Assembly and Testing of Motion Control Assemblies for Advanced Devices and Systems • Complete Test Device, Design & Development • Minitab Statistical Analysis Tools • Computer Aided Machining (CAM) • Six Sigma black belt expertise Precision Gears Precision Gearboxes Precision Mechanical Components Precision Bearings CGI-PTGuide4.16-Spread.indd 12 5/2/16 11:48 AM
  15. 15. www.cgimotion.com 800.568.GEAR (4327) Manufacturing Engineering Support Worldwide SupportTesting & Validation CGI’s Quality Equipment: Highly Qualified Inspection Department • Zeiss Contura Coordinate Measuring Machine (CMM) • Brown and Sharpe Coordinate Measuring Machine (CMM) • PECo Next Dimension 300 Gear Analyzer • Micro-Vu Vertex Vision System • Starrett Optical Comparators with Digital Readout • TESA Scanner • PECo Dual Flank Test Roll Checker • Micro Check Dual Flank Test Roll Checkers • Vari-Roll Dual Flank Test Roll Checkers • Inspection Xpert software for First Article Reports CGI Enables Design Excellence. Precision Mechanical Assemblies Electro-mechanical AssembliesCustomized Components CGI-PTGuide4.16-Spread.indd 13 5/2/16 11:48 AM
  16. 16. PowerTransmission REFERENCEGUIDE 14 DESIGN WORLD — MOTION 4 • 2016 motioncontroltips.com | designworldonline.com MANY applications call for converting rotary motion into motion that moves in a straight line. For these applications, linear electric or electromechanical actuators handle the task efficiently. In fact, today’s actuators are so efficient that the variety available for different design needs has proliferated. That means that actuators today are easier than ever to integrate into machinery; they’re also less costly. Electric actuators turn an electric motor’s power into linear motion in one of three ways: through a linear motor, belt or screw drive. Linear motors are the most technologically advanced and efficient method of directly transmitting the power of the motor into the motion of the actuator. Instead of the rotor rotating in the stator, the rotor travels in a linear, flat-array fashion along the stator. Belt drive actuators are less costly, but can still move loads at fairly high linear speeds. Because the motor is separate from the drive, the mechanical advantage can increase thrust speed. The disadvantage of belt drives is that they wear over time and require maintenance. ELECTRIC ACTUATORS: SMART DESIGNS EXCEL LISA EITEL SENIOR EDITOR @DW_LISAEITEL ElectricActuators_PT2016_V3.indd 14 4/29/16 10:40 AM
  17. 17. ELECTRIC ACTUATORS 15DESIGN WORLD — MOTIONmotioncontroltips.com | designworldonline.com 4 • 2016 Most screw drives take the form of either rod-style actuators or rodless cylinders. A motor transmits power through a coupler or pulley arrangement to rotate the screw and translate a nut along the screw axis. Attached to this nut is either the rod or saddle of the actuator. Screw drives can use roller, ball or leadscrews. Electric actuators have several benefits over hydraulic or pneumatic actuators. For one, the operation is cleaner because they operate without the need for fluids or ancillary equipment. They have the ability to integrate power, control and actuation mechanisms into one device. And they combine force, velocity and positioning in a single, compact motion control device. Another advantage is the ability to constantly monitor feedback directly from the motor and adjust performance accordingly. Though not necessary for every application, closed-loop operation has the ability to adjust and correct variances in the operation, resulting in repeatable and accurate motion with every move. Today, the prices for drives for electric actuators have come down, which has opened new application uses for the linear actuator. So, electric actuators are more viable for applications where hydraulic, pneumatic and manual operations once ruled. In many applications, servomotors are replacing induction motors because of their performance and energy efficiency. Direct drives are replacing traditional motor-gearbox combinations because of their high dynamic performance, high precision and long life. And electric actuators are replacing pneumatic cylinders in many applications for similar reasons. But the biggest improvements in the last five to ten years can be found in the control systems integrated with electric actuators. Faster bus systems, like industrial Ethernet and real-time communication, make the use of electric actuators simpler. Servo systems require fast communication and exchange of real-time data between the drive and the overlaid machine control. The bus was always the bottleneck in these systems. Now, with the much higher data rates and real-time capacity of industrial Ethernet, the integration and the use of electric actuators is easier. Stepper and servo drive options with Ethernet protocols (Ethernet IP, Modbus, TCP) turn single-axis actuators into simple, low-cost motion devices with infinite positioning, precise control and longer life. Electric linear actuators are an alternative to pneumatic cylinders in several applications because of the flexibility they deliver in the design of production processes and production monitoring systems. In conveying applications, for example, diverting and sorting functions are more frequently controlled using electric actuators. Typically, pneumatic actuators have been used, but the required manual adjustments were often subject to human error. Plus, the pneumatic actuators could only handle a small amount of variability in product sizes. Electric actuators are flexible by design. For example, material handling applications have experienced an increase in the variety and variability of package sizes. In packaging machines, consumer products manufacturers are Linear positioning actuators of extremely long stroke lengths — such as this LoPro linear actuator from Bishop- Wisecarver — typically use belt drives. Polyurethane belting is quiet and delivers long mechanical actuation with good accuracy and high speeds. LoPro actuators are three to 8 m long, but units to 15 m are possible. Tolomatic ERD hygienic all-stainless-steel electric cylinders have a roller-screw option that boosts maximum thrust to 7,868 lbf (35.6 kN) for better life and performance under high duty cycles than ballscrew models. ElectricActuators_PT2016_V3.indd 15 4/29/16 10:40 AM
  18. 18. PowerTransmission REFERENCEGUIDE 16 DESIGN WORLD — MOTION 4 • 2016 motioncontroltips.com | designworldonline.com NSK’s MCM Series Monocarrier includes a ballscrew, linear guide and supports in one compact structure. It boosts accuracy and reduces installation time, and some versions are available through a Quick Ship Program. producing more package sizes with the same manufacturing lines, which require equipment to be adaptable enough to handle different product sizes and types. Electric actuators easily handle these variability requirements and, over the life of the motion system, can be less expensive. SELECTING AN ELECTRIC ACTUATOR The process for selecting an electric actuator is similar to one for hydraulic or pneumatic actuators, with a few differences. Here are the essentials. Start with the motion profile. This establishes the demands for velocity and time as well as force (or torque) and the required travel distance. This is also the place to determine the maximum stroke needed as well as maximum and minimum speed requirements. Then calculate the load. This can have many different components including inertial load, friction load, the external applied load, as well as the gravitational load. Load calculations also depend on the orientation of the actuator itself, whether it’s horizontal or vertical. Duty cycle is another important factor. This is defined as the ratio of operating time to resting time and is usually expressed as a percentage. The cycling rate may be in seconds, minutes, hours or even days, and knowing the operating hours per day may also be necessary. Knowing the duty cycle helps the engineer estimate the system life requirements and can also eliminate problems such as overheating, faster wear and premature component failure due to an incorrectly sized actuator. Know the positional accuracy and precision demanded by the application. The actuator’s precision should meet or exceed the application’s requirements for accuracy, backlash, and straightness and flatness of linear motion. This directly impacts the cost of the system; if the application doesn’t demand high accuracy or precision, then there is no need to buy a more expensive actuator when a less expensive one will satisfy the demands of the application. Aside from the technical specifications mentioned above, there is also the need to select the proper configuration for the actuator in the final design. This includes mounting considerations and the need for any other external components, such as holding brakes and communication and power cables. Lastly, consider the operating environment for the actuator. What are the temperature requirements? Are there any contaminants such as water, oil or abrasive chemicals? Contaminants can affect seals and impact the working life of the actuator. In such cases, selecting the appropriate IP rating for an application can guard against the effects of contaminants. ElectricActuators_PT2016_V3.indd 16 4/29/16 10:41 AM
  19. 19. 1.800.255.4773 www.nskamericas.com BALL BEARINGS | ROLLER BEARINGS | LINEAR MOTION PRODUCTS | TECHNICAL SERVICES nsk k1TM lubricaTion uniT Experience long-term, maintenance-free operation with NSK K1™ Lubrication Units. These patented units provide fresh, continuous oil flow onto the rail or shaft during operation, making them ideal for environments where grease replenishment is undesirable or where grease is easily washed away. Available on NSK linear guides, ball screws, Monocarrier™ actuators and Robot Modules, K1™ Lubrication Units prolong life for up to 5 years or 10,000 km operational distance. MAINTENANCE- fREE OPERATION. WORRy-fREE DESIGN. NPA-SL-020 Design World ad_K1 Unit[250314]v1.indd 1 2014-03-25 3:14 PM NSK 8-15.indd 17 4/29/16 10:04 AM
  20. 20. PowerTransmission REFERENCEGUIDE 18 DESIGN WORLD — MOTION 4 • 2016 motioncontroltips.com | designworldonline.com This is a custom loading-station scissor lift that uses a SERAPID 40 chain actuator. Retractable to table-top level, the platform can smoothly lift a heavy load more than 10 ft. A space- saving chain storage magazine fits compactly at the bottom. MECHANICAL COMPONENTS AT THE HEART OF MOTION DESIGN LISA EITEL • SENIOR EDITOR • @DW_LISAEITEL RIGID-CHAIN actuators work by pairing a drive (usually an electric motor) with a length of chain sporting shoulders on each link. The motor output shaft—fitted with a specialty sprocket or pinion—applies tangential force to the chain. Then the chain comes out and straightens, and its links’ shoulders lock to form a rigid series. When the motor runs in the opposite direction, the chain shoulders disengage and allow for coiling. Inside the actuator body, reaction plates and guides counter thrust resistance and keep the chain on track. Links travel around the pinion to exit the actuator body along the stroke path. Here, the motor’s torque comes to act as forward thrust via the link shoulder to the rest of the links’ shoulders. The last link in the chain before the load has geometry that puts the thrust higher than the articulation axis. This makes a moment that effectively locks the link shoulders. In reverse, pulling force acts along the links’ cross axes. Rigid-chain actuators have the mechanical benefits of conventional chain but can act in horizontal push setups or vertically as jacks. Plus they’re compact. In contrast, traditional chain drives can only pull, so need two drives for bidirectional motion. Traditional screw jacks for vertical power transmission need space for retraction that’s as long as the working stroke itself. Before specifying a rigid-chain actuator, determine the application’s total load, including the transported load, acceleration forces, external environmental forces, and that due to friction—with a coefficient between 0.05 and 0.5 for typical rigid-chain actuator setups. Next, determine what type of actuator body and chain-storage magazine the application can accommodate. Determine whether the chain will need to change direction on its way from the magazine to actuator body. Actuators usually feed chain around 90° or 180° turns. Note that rigid-chain actuators can work alone or in tandem. Twin-chain setups deliver high positioning accuracy and stability where loads are large or bulky. Common rigid chain has two rows of link plates and shoulders; duplex chain has three; other options abound. Image courtesy iwis Drive Systems DW half page rv RigidChainActuators_PTGuide_V3.LE.MD.indd 18 4/29/16 10:43 AM
  21. 21. Choose a rigid-chain actuator to satisfy the design geometry. ... but guided chain is most stable. Unguided chain with shoulders up coils downwards ... Common rigid-chain arrangements Pinion Actuator body Input drive shaft Chain link shoulders RIGID CHAIN ACTUATORS Unguided chain with shoulders up coils downward, which is useful but not always stable enough for long strokes. That with shoulders down (here, bottom) is slightly more stable. Use guided chain wherever space permits. Here, a pushing bar acts as a yoke to keep loads steady, with optional hooks for pulling as well. Optimized geometry has the force vector act on the load’s center for balance. If twin-chain setups are impossible, consider adding framework to guide awkward loads. Guides on the chain also help maintain stability—even over very long strokes—because they address side and buckling forces. Such guides come in different shapes with different crampons and subcomponents to engage the chain. Where use of chain guides is impossible, most designs run the chain with link shoulders down for moderate stability. Some last design notes: Standard chain is carbon steel to withstand heat to 200° C, but stainless, high-temperature, and coated chain for long life are other options. The required length of chain is total design stroke plus a few links to engage the actuator pinions. As with any power- transmission setup, consult the manufacturer for tips and guidance on determining necessary drive power and other details. SERAPID Inc. | 34100 Mound Rd. | Sterling Heights, MI | Tel +1 586-274-0774 | info-us@serapid.com | www.serapid.com SOLUTIONS FOR PRECISION MOVEMENT OF VERY HEAVY LOADS Press-mounted dual push-pulls QUICK DIE CHANGE STAGE AND ORCHESTRA LIFTS CUSTOM ENGINEERED SYSTEMS INDUSTRIAL LIFTS LinearBeam guided push-pull LinkLi li columns RollBeam Telescopic push-pull DW half page rv.indd 1 4/12/2016 2:17:33 PM RigidChainActuators_PTGuide_V3.LE.MD.indd 19 4/29/16 2:58 PM
  22. 22. PowerTransmission REFERENCEGUIDE 20 DESIGN WORLD — MOTION 4 • 2016 motioncontroltips.com | designworldonline.com This cutaway, courtesy of Nook Industries, shows the inner workings of a ballscrew, most notably the recirculating balls and the deflector, in relation to the screw assembly. BALLSCREWS B A S I C S O F MILES BUDIMIR • SENIOR EDITOR • @DW_MOTION BALLSCREWS are a mainstay of motion actuation. Compared to similar actuation methods such as leadscrews, they typically cost a bit more but are generally more accurate. They also boast higher efficiencies, even though they demand more lubrication because of the use of recirculating balls. The basic components of a ballscrew are a nut, a screw with helical grooves, and balls (often made from steel, ceramic, or hard plastic material) that roll between the nut, the screw and the grooves when either the screw or nut rotates. Balls are routed into a ball return system of the nut and travel in a continuous path to the ball nut’s opposite end. Seals are often used on either side of the nut to prevent debris from compromising smooth motion. Recent advances in manufacturing and materials have improved ballscrew performance so machine designers today can get better linear motion with them at lower cost. Some improvements include the fact that the latest generation of ballscrews has more load density than ever, giving designers higher capacity from a smaller package. There is also a trend toward more miniaturization, but also faster ballscrews with rolled and ground screw manufacturing methods. Ballscrews suit applications needing light, smooth motion, applications requiring precise positioning, and when heavy loads must be moved. Examples include machine tools, assembly devices, X-Y motion, Z motion, and robots. Ballscrews are usually classified according to factors such as lead accuracy, axial play and preload, and life/load relationship. Lead accuracy refers to the degree to which the shaft’s rotational movements are translated into linear movement. With lead accuracy and axial play determined by the manufacturing method of the ballscrew shaft and the assembly of the nut, high lead accuracy and zero axial play is generally Ballscrews_PTGuide_V2-mb.indd 20 4/29/16 2:26 PM
  23. 23. © 2015 by AMETEK Inc. All rights reserved. Nothing moves air with more rock-solid reliability than AMETEK® Rotron regenerative blowers. Fifteen years’ service life is not unusual. These low-pressure, high-volume blowers feature rugged, compact construction and quiet operation. Their proven design makes them ideal in applications from chemicals, wastewater and furnaces to vapor recovery and more. Plus, they’re backed by the industry’s most knowledgeable engineering experts. AMETEK can customize your blower for harsh environments, high voltage and specialized applications, too. So make your next air-moving challenge a breeze. Call us at +1 330-673-3452 or visit our website to get started. What’s 15 years to one of our blowers? A warm-up. 100 East Erie Street Kent, OH 44240 ametekdfs.com AMETEKDFS Regen Blower Ad_9x10.875.indd 1 6/1/15 5:03 PM AMETEK 6-15 (NEW AD).indd 21 4/29/16 10:04 AM
  24. 24. 22 DESIGN WORLD 4 • 2016 www.designworldonline.com REFERENCE GUIDE POWER TRANSMISSION www.cjmco.com Phone: 860-643-1531 291 Boston Tpke, Bolton, CT 06043 Engineering Solutions for Clutches & Brakes Clutches,Brakes & Power Transmission Products •electrical, mechanical, pneumatic & hydraulic models •system design and integration •expert engineers working on every order Highest Torque in the Smallest Space ... or the largest. Maxitorq® clutches and brakes deliver power, reliability and are customized to meet your exact needs. Land, sea and air – CJM is everywhere. AS9100C:2009/Certified associated with relatively higher-cost precision ground ballscrews, while lower lead accuracy and some axial play is associated with lower cost rolled ballscrews. Fabricated by rolling or other means, ballscrew shafts yield a less precise but mechanically efficient and less expensive ballscrew. Axial play is the degree to which a ball nut can be moved in the screw axis direction without any rotation of either nut or screw. Preload is applied to eliminate axial play. The process of preloading removes backlash and increases stiffness. Ball recirculation inside the ball nut can affect precision and repeatability. Thus, ball nuts are available with a range of preload options to reduce or remove the axial play as they rotate around the screw. Minimal axial play allows better accuracy, for example, because no motion is lost from the clearance in the balls as they reengage. There are several techniques for preloading. Some common methods include oversizing the balls inside the nut housing; using the so-called “double-nut” or “tension nut” method; or by using a manufactured offset in the raceway spiral to change the angle of ball engagement (the “lead shift” method) and deliberately force the balls into a preload condition. Each method has its advantages and disadvantages, but all serve to minimize or eliminate backlash between the nut and screw. Perhaps the biggest overall benefit of a ballscrew is that it has high efficiencies that can be well over 90%. By contrast, Acme lead screws average about 50% efficiency or less. There are also minimum thermal effects. Backlash can be eliminated through preloading. Ballscrews also offer smooth movement over the full travel range. The higher cost of ballscrews can be offset by decreased power requirements for similar net performance. One drawback to ballscrews is that they require high levels of lubrication. Ballscrews should always be properly lubricated, with the correct type of lubricant, to prevent corrosion, reduce friction, extend operating life, and ensure efficient operation. Because ballscrews are a bearing system, they’ll need some type of lubrication to avoid metal-to-metal contact of the balls in the raceway. While the lubrication choice can be either oil or grease, it’s advisable to avoid solid additives (such as graphite) as they will clog the recirculation system. An NLGI no. 2 type grease is recommended but it should also depend on the application, whether food-grade or another special type of lubrication is required. Ballscrews, especially those used in machine tools, generally require lubricants with EP additives to prevent excessive wear. The lube amount will be fixed, but the frequency of lubrication will vary depending on factors such as the move cycle characteristics, or contamination in the environment. Contaminated lubrication can increase friction. In addition, ballscrews can fail if the balls travel over metal chips or dirt in the ball thread raceway. Using lubricants recommended by machine tool manufacturers can help prevent this effect. Using telescopic covers or bellows can help keep ballscrews clean when used in environments with many contaminants. A sample ballscrew assembly, such as the Precision Metric Ball Screws (PMBS) series from Nook Industries, features a single nut with flange, uses precision thread-rolling technology and is available in a wide range of leads and diameters. Ballscrews_PTGuide_V2-mb.indd 22 4/29/16 10:47 AM
  25. 25. Together a winning combination for today’s servomotor applications. Our ServoClass® couplings have been recently redesigned to enable your actuator to go even faster and achieve the positional accuracy that will take your designs to the next level. Our couplings will do all this with low bearing loads. 3 New sizes now available. Now, size, select and see the right ServoClass® coupling solution for your application with Zero-Max 3D CAD files. Check our FAST deliveries. www.zero-max.com 800.533.1731 © 2010 ZERO-MAX Your ball screw Your servomotor Our coupling # Zero-Max_full_pgs_r10_Design World 2/12/10 4:02 PM Page 1 Zero Max ad 8-15.indd 23 4/29/16 10:05 AM
  26. 26. PowerTransmission REFERENCEGUIDE DESIGN WORLD — MOTION 4 • 201624 BEARINGS REVIEW OF IT’S EASY for bearings to go unnoticed—an out of sight, out of mind mentality. This attitude is common among so many because bearings are simple, internal machine elements. However, that doesn’t make them any less crucial for motion applications. The purpose of a bearing is to reduce frictional forces between two moving parts by giving a surface something to roll on, rather than slide over. There are basic features that all bearings share, but specific application needs demand many different variations of this universal motion system component. A bearing usually consists of smooth rollers or metal balls and the smooth inner and outer surfaces, known as races, that the rollers or balls roll against. These rollers or balls act as the load carrier for the device, allowing it to spin freely. Bearings typically encounter two kinds of load: radial and axial. Radial loads occur perpendicular to the shaft, while axial loads occur parallel to the shaft. Depending on the application the bearing is being used in, some bearings experience both loads simultaneously. There are many different types of bearings, each suitable for different purposes in varying applications. BALL BEARINGS One of the most common forms of bearings is the ball bearing. As the name implies, ball bearings use balls to provide a low friction means of motion between two bearing races. Since the contact area between the balls and races is so small, ball bearings cannot support as large a load as other bearing types and are best suited for light to moderate loads. However, their small surface contact also limits the heat generated by friction, meaning that ball bearings can be used in high-speed applications. ROLLER BEARINGS Possibly the oldest form of bearing, roller bearings can be spherically or cylindrically shaped and are commonly used in applications like conveyor belt rollers. Because of their shape, roller bearings have greater surface contact than ball bearings, and are thus able to handle larger loads without deforming. Their shape also allows for a moderate amount of thrust load since the weight is distributed across cylinders instead of spheres. MIKE SANTORA • ASSOCIATE EDITOR • @DW_MIKESANTORA Plastics for longer life® 3 times lighter than stainless DryLin® aluminum lead screws with optimized geometry for high- efficiency and long service life. Variety of nut types available in 5 materials, including FDA and high-temperature compliant. Learn more at: www.igus.com/DryLin® Bearings_PTGuide_V3.indd 24 4/29/16 10:53 AM
  27. 27.  BEARINGS 25DESIGN WORLD — MOTIONmotioncontroltips.com | designworldonline.com NEEDLE ROLLER BEARINGS When you need to reduce friction between two moving parts but have very limited space to do so, a needle roller bearing may be just what you’re looking for. A needle roller bearing is a roller bearing with rollers whose length is at least four times their diameter. Despite their low cross section, the large surface area of the needle roller bearing allows them to support extremely high radial loads. They usually consist of a cage, which orients and contains the needle rollers and an outer race, which is sometimes the housing itself. The bearings can often be found in two different arrangements. The first is a radial arrangement, in which the rollers run parallel to the shaft. The second is a thrust arrangement, in which the rollers are placed flat in a radial pattern and run perpendicular to the shaft. These bearings are often used in automotive applications, such as rocker arm pivots, pumps, compressors and transmissions. The drive shaft of a rear-wheel drive vehicle typically has at least eight needle bearings (four in each U joint) and often more if it is particularly long, or operates on steep slopes. Spherical roller bearings like Koyo’s RZ Spherical Roller Bearing have a greater surface contact than ball bearings, and are thus able to handle larger loads without deforming. THRUST BALL BEARINGS Thrust ball bearings are designed for use in applications with primarily axial loads and are capable of handling shaft misalignment. These bearings are also useful in high-speed applications, such as in the aerospace and automotive industries. THRUST ROLLER BEARINGS Thrust roller bearings are designed so that the load is transmitted from one raceway to the other, meaning that these bearings can accommodate radial loads. Bearings like these also have a self-aligning capability that makes them immune to shaft deflection and alignment errors. TAPERED ROLLER BEARINGS Tapered roller bearings feature tapered inner and outer ring raceways with tapered rollers arranged between them, angled so the surface of the rollers converge at the axis of the bearing. These bearings are unique in that, unlike most bearings that can handle either axial or radial loads, they can handle large amounts of load in both directions. A single row taper bearing is limited in that it can only take high axial loads from one direction, but if adjusted against a second tapered roller bearing, that axial load is counteracted. This allows the bearings to accept high radial and axial loads from multiple directions. Test 3621: Chainflex® control cable CF98.05.04 Has withstood more than 138 million strokes at a radius of 3.2 x d Test information and details available online: chainflex.com/test3621 Tested and Proven 138 million cycles Test3621 Bearings_PTGuide_V3.indd 25 4/29/16 2:33 PM
  28. 28. 26 DESIGN WORLD — MOTION 4 • 2016 motioncontroltips.com | designworldonline.com PowerTransmission REFERENCEGUIDE Depending on application requirements, some ball bearing are made with magnetic, lubricant-free motion plastics like this igus xiros M180 which uses a lightweight polymer ball bearing. The ability of a tapered roller bearing to accommodate angular misalignment of the inner ring in relation to the outer ring is limited to a few minutes of arc. As with other roller bearings, tapered roller bearings must be given a minimum load, especially in high speed applications where the inertial forces and friction can have a damaging effect between the rollers and raceway. LINEAR MOTION BEARINGS Linear motion bearings are specifically designed to allow motion in one direction and are typically used to carry a load on a slide or rail. They can be powered by a motor or by hand and experience over turning moments of force instead of radial and axial loads. PLAIN BEARINGS Plain bearings are the simplest form of bearing available, as they have no moving parts. They are often cylindrical, though the design of the bearing differs depending on the intended motion. Plain bearings are available in three designs: journal, linear and thrust. Journal style bearings are designed to support radial motion where a shaft rotates within the bearing. Linear bearings are often used in applications requiring slide plates, as these bearings are designed to permit motion in a linear motion. Finally, a plain thrust bearing is designed to do the same job as its roller bearing counterpart, but instead of using cone shaped rolling elements, the bearing uses pads arranged in a circle around the cylinder. These pads create wedge-shaped regions of oil inside the bearing between the pads and a rotating disk, which supports applied thrust and eliminates metal-on-metal contact. Out of all the bearing types available, plain bearings tend to be the least expensive. They can be made from a variety of materials including bronze, graphite and plastics, such Bearings_PTGuide_V3.indd 26 4/29/16 10:55 AM
  29. 29.  BEARINGS 27DESIGN WORLD — MOTIONmotioncontroltips.com | designworldonline.com 4 • 2016 The greater surface contact of roller bearings enables them to handle larger loads without deforming. Demonstrating just a few of the many types of roller bearings, here we see a needle, spherical, tapered and cylindrical roller bearing. Image courtesy of AST. as Nylon, PTFE and polyacetal. Improvements in material characteristics have made plastic plain bearings increasingly popular in recent years. Plain bearings of all types, however, are lightweight, compact and can carry a substantial load. As far as lubrication is concerned, some plain bearings require outside lubrication while others are self-lubricating. Plain bearings made of bronze or polyacetal, for example, contain lubricant within the walls of the bearing, but require some outside lubrication to maximize performance. For other plain bearings, the material itself acts as the lubricant. Such is the case with bearings made from PTFE or metalized graphite. The growing popularity of plain plastic bearings and increasingly stringent industry standards has resulted in more consumers requiring the bearings to meet FDA and RoHS standards. There has even been a call for the bearings to meet the standards of EU directive 10/2011/EC, which also takes the material manufacturing process into account. Common applications for drawn cup needle roller bearings like this from Koyo include: precision gear boxes, machine tool, medical equipment, precision assembly equipment, robotics, after-market racing equipment and aerospace. APPLICATIONS Bearings are all around us in everyday life and most of the time they go unnoticed. But without them, many of the tasks we undertake would move along much less smoothly. The ball bearings’ simple design, ability to operate at high speeds and relatively low- maintenance requirements, makes them one of the most common roller bearings found in a variety of industrial applications. For example, deep groove ball bearings are often used in small- to medium-sized electric motors because of their ability to accommodate both high speeds and radial and axial loads. Self-aligning ball bearings, on the other hand, are ideal for use in fans. These bearings have two rows of balls with a common raceway in the outer ring. This design allows for angular misalignment while maintaining running accuracy. They are, however, one of the most difficult bearings to install correctly. Tapered roller bearings are another form of bearing that just about every industry depends on one way or another. They are usually found in applications where support for axial and radial loads is required, such as in a tire hub where the bearing must deal with the radial load from the weight of the vehicle and the axial load experienced while cornering. These bearings are also commonly found in gearboxes where they are generally mounted with a second bearing of the same type in a face-to-face or back-to-back orientation. They provide rigid shaft support, keeping deflection to a minimum. This reduced shaft deflection minimizes gear backlash. Tapered bearings also have the advantage of having less mass but high efficiency, however this does limit their overall speed. In applications where bearings are mounted vertically, they are typically oriented in a face-to- face setup, while horizontal applications use a back-to-back setup. Some pumps use this design because of shaft deflection concerns. Bearings_PTGuide_V3.indd 27 4/29/16 2:36 PM
  30. 30. 28 DESIGN WORLD — MOTION 4 • 2016 motioncontroltips.com | designworldonline.com PowerTransmission REFERENCEGUIDE BELTS & PULLEYS THE BASICS OF Belts and pulleys lift loads, use mechanical advantage to apply forces, and transmit power.They also form the basis of industrial conveyors big and small. Here are the fundamentals of their operation and how to apply them. LISA EITEL • SENIOR EDITOR • @DW_LISAEITEL Shown here is a Gates Carbon Drive CDN system—designed to be lower in cost for new bike applications. It leverages new materials and geometries, with nine carbon cords embedded within engineered polymer belt and a patented 11-millimeter tooth pitch profile for lower tension. Like many new belt applications, it replaces chain drives. INDUSTRIAL belt drives consist of rubber belts that wrap around drive pulleys, in turn driven by electric motors. In a typical setup, the belt also wraps around one or more idler pulleys that keep the belt taut and on track. The main reasons that engineers pick belt drives over other options is that modern varieties require little if no maintenance; they’re less expensive than chain drives; and they’re quiet and efficient, even up to 95% or more. In addition, the tensile members of today’s belts— cords embedded into the belt rubber that carry the majority of the belt load—are stronger than ever. Made of polyester, aramid, fiberglass or carbon fiber, these tensile cords make today’s belt drives thoroughly modern power-transmission devices. Manufacturers generally describe belts and pulleys with five main geometries. Pitch diameter is the drive pulley’s diameter. Center distance is the distance between the two pulleys’ centers. Minimum wrap angle is a measure of how much the belt wraps around the smallest pulley. Belt length is how long the belt would be if cut and laid flat. Finally, in the case of toothed belts (also called synchronous belts) the pitch is the number of teeth per some length—so a 3-mm pitch means that the belt has one tooth every 3 mm, for example. APPLYING SYNCHRONOUS BELTS Some general guidelines are applicable to all timing belts, including miniature and double-sided belts. First of all, engineers should always design these belt drives with a sufficient safety factor—in other words, with ample reserve horsepower capacity. Tip: Take note of overload service factors. Belt ratings are generally only 1/15 of the belt’s ultimate strength. These ratings are set so the belt will deliver at least 3,000 hours of useful life if the end user properly installs and maintains it. The pulley diameter should never be smaller than the width of the belt. BeltsPulleys_PTGuide_V1.LE.indd 28 4/29/16 4:10 PM
  31. 31. 29DESIGN WORLD — MOTION 4 • 2016 BELTS & PULLEYS Custom Synchronous Drives Precise. Reliable. Cost Effective. Timing Pulley Stock Guaranteed When You Need It. Manufacturers of Power Transmission and Motion Control Components Concentric Maxi Torque Stock and Custom Keyless Hub-to-Shaft Connection System Email or call to get your CMT Stock Products Catalog Order today. Ships today! Custom Machine & Tool Co., Inc. (800)355-5949 • sales@cmtco.com www.cmtco.com Precise. Reliable. Trusted. American Engineering • American Made © 2016 Custom Machine & Tool Co., Inc. As mentioned, belts are quieter than other power- transmission drive options … but they’re not silent. Noise frequency increases proportionally with belt speed, and noise amplitude increases with belt tension. Most belt noise arises from the way in which belt teeth entering the pulleys at high speed repeatedly compresses the trapped pockets of air. Other noise arises from belt rubbing against the flange; in some cases, this happens when the shafts aren’t parallel. Pulleys are metal or plastic, and the most suitable depends on required precision, price, inertia, color, magnetic properties and the engineer’s preference based on experience. Plastic pulleys with metal inserts or metal hubs are a good compromise. Tip: Make at least one pulley in the belt drive adjustable to allow for belt installation and tensioning. Also note that in a properly designed belt drive, there should be a minimum of six teeth in mesh and at least 60° of belt wrap around the drive pulley. Other tips: • Pretension belts with the proper recommended tension. This extends life and prevents belt ratcheting or tooth jumping. • Align shafts and pulleys to prevent belt-tracking forces and belt edge wear. Don’t crimp belts beyond the smallest recommended pulley radius for that belt section. • Select the appropriate belt for the design torque. • Select the appropriate belt material for the environment (temperature, chemical, cleaning agents, oils and weather). Belt-and-pulley systems are suitable for myriad environments, but some applications need special consideration. Topping this list are environmental factors. Dusty environments do not generally present serious problems as long as the particles are fine and dry. In contrast, particulate matter can act as an abrasive and accelerates belt and pulley wear. Debris should be prevented from falling into belt drives. Debris caught in the drive is generally either forced through the belt or makes the system stall. In either case, serious damage occurs to the belt and related drive hardware. Light and occasional contact with water—during occasional washdowns, for example—has little serious effect. However, These PowerGrip TruMotion timing belts from Stock Drive Products have nylon tooth facing for longer and quieter running and less dust. Fiberglass tensile cords resist elongation and have a high flex life. BeltsPulleys_PTGuide_V1.LE.indd 29 5/3/16 9:22 AM
  32. 32. PowerTransmission REFERENCEGUIDE 30 DESIGN WORLD — MOTION 4 • 2016 motioncontroltips.com | designworldonline.com prolonged contact with constant spray or submersion can significantly reduce tensile strength in fiberglass belts and make aramid belts break down and stretch out. In the same way, occasional contact with oils doesn’t damage synchronous belts. But prolonged contact with oil or lubricants, either directly or airborne, significantly reduces belt service life. Lubricants cause the rubber compound to swell, break down internal adhesion systems and reduce felt tensile strength. While alternate rubber compounds may provide some marginal improvement in durability, it’s best to prevent oil from contacting synchronous belts. The presence of ozone can be detrimental to the compounds used in rubber synchronous belts. Ozone degrades belt materials in much the same way as excessive temperatures. Although the bumper materials used in belts are compounded to resist the effects of ozone, eventually chemical breakdown occurs and they become hard and brittle and begin cracking. The amount of degradation depends on the ozone concentration and generation of exposure. Rubber belts aren’t suitable for cleanrooms, as they risk shedding particles. Instead, use urethane timing belts here … keeping in mind that while urethane belts make significantly less debris, most can carry only light loads. Also, none have static conductive construction to dissipate electrical charges. Shown here are Baldor-Maska sheaves for V-belt drives,also called friction drives for the way they operate. Minimum allowable sheave diameter depends on the belt shape and material, whether that’s synthetic, neoprene, urethane, or rubber. This setup has an electronic warning system from ContiTech to alert operators when a conveyor is elongating or at risk of ripping. Called CONTI PROTECT and most useful on industrial and mining conveyors, the system uses magnetic markings on the belts to track irregularities in the splice length and detects longitudinal rips before they grow. Such monitoring systems are just one example of how belt-drive technologies have kept pace with 21st-centrury design concepts. BeltsPulleys_PTGuide_V1.LE.indd 30 4/29/16 2:59 PM
  33. 33. www.designworldonline.com 4 • 2016 DESIGN WORLD 31 BRAKES & CLUTCHES BRAKES and clutches are a mainstay in motion designs that need to stop, hold or index loads. Especially over the last five years, a technology trend toward application-specific designs has quickened as several industries are pushing the performance envelope of stock components. Brakes are used to stop a load, typically a rotating load, while clutches are used to transfer torque. There are many different types of brakes and clutches. A brake would be used in applications where accurate stopping of the load is needed and the motor will stop as well. A clutch would be used in applications where it’s desirable to engage or disengage a load and motor while leaving the motor to run all the time. When a clutch is used, the load will be allowed to coast to a stop. A clutch and brake combination would be used where the load will be started and stopped while the motor continues to rotate. Both clutches and clutch brakes can mount to a motor shaft or be base-mounted and have input through a belt drive, chain drive or coupling. The motor horsepower and motor frame size play a key role in determining which specific brake or clutch to select. In the case of base-mounted units, it may be necessary to define the RPM at that location. Manufacturers provide quick selection charts where unit size is determined by finding the intersection of motor horsepower and speed at the clutch shaft. The charts are commonly created using the dynamic torque capacity for the product and the torque capacity for the motor plus an overload factor of some value. Using this method presumes that you’ve selected a motor that’s sized appropriately to the application. In applications where cycle rates are considered aggressive for the inertia of the load, it’s a good idea to consult with the application support staff of the manufacturer regarding the heat dissipation capacity. Coil voltage is another consideration. The most common options are 6, 24 and 90 Vdc with 90 V being widely preferred in North American markets, while 24 V is more common in Europe. In both cases, brake and clutch manufacturers can offer power supplies to convert ac to dc if required. BRAKES & CLUTCHES MORE INDISPENSABLE THAN EVER Shaft-mounted electric clutches from New Torque have a static torque rating from 15 to 202 Nm, voltage of 24 to95 Vdc, and power of 16 to 50 W. Some clutches and brakes — as the ones from Carlyle Johnson Machine Company shown here — can last 15 years on average, with some products lasting 50 years or more. Shown here is an ac solenoid shoe Brake from Ametek. Gemco industrial brakes stop industrial machines in steel mills, gantries, cranes, and commercial laundry equipment. They are tough and long-lasting. This is a Force Control Industries coupler brake. In fact, the company’s Posistop and MagnaShear coupler brakes mount between motors and reducers, so engineers can eliminate separate brake motors. LISA EITEL • SENIOR EDITOR • @DW_LISAEITEL BrakesClutches_PTGuide_V3.indd 31 4/29/16 11:14 AM
  34. 34. 32 DESIGN WORLD — MOTION 4 • 2016 motioncontroltips.com | designworldonline.com ENGINEERS can use a multitude of cables (including data, coaxial, and instrumentation cables) in industrial settings for control networking, low and medium- voltage power transmission and distribution, and more. Most cables that distribute power to motors are low-voltage designs rated for 2,000 V and below. That said, some facilities with partial responsibility over the utility power they consume use medium-voltage cables rated for 2,000 to 35,000 V. Available as both single and multi-conductor designs, these power cables must be able to withstand high mechanical loads, speeds and accelerations. Common applications include machine tools, cranes, conveyors, portable designs and stationary heavy-duty equipment. Such cables can supply temporary ac or dc power to motors and generators, and can operate indoors and outdoors, depending on their temperature rating. The proper cable for an application depends on its function and environment. For instance, only use an unshielded cable when it will operate in an enclosed space only accessible by trained professionals. Such enclosures prevent electromagnetic interference and keep plant personnel safely away from potentially live electrical charges. Manufacturers usually construct low-voltage cables with aluminum or copper conductors, insulation and jacketing. Conductors can range anywhere from finely stranded bare copper wires to bunched strands of tinned annealed copper. They come in both shielded and unshielded versions and usually must be flame retardant and oil resistant. Power cables feature conductors that are either stranded in layers inside or bundled or braided. The stranded design is easier to manufacture so costs less. It features long, layered cores and firm strands wrapped with an extruded jacket. In the bundled or braided design, the conductors are braided around a tension-proof center. By eliminating the layers, a uniform bend radius is ensured. To accommodate the complex and sometimes cramped spaces where they operate, industrial power cables must also have tight bending radii, ranging anywhere from 5 to 15 times the overall cable diameter. Jacketing is also crucial to meet these bending radii requirements. Therefore, the use of flexible materials such as PVC, TPE and CPE not only helps these cables bend and flex but also protects them from environmental damage. Because their materials, shielding and jacketing all vary, so do industrial power cables’ installation techniques. Installers can put cables into fixed duct, shafts, and conduit; direct-bury or even immerse the cables in water in water; or lay cables into open-air applications. Depending on where a cable is manufactured and used, it must meet a variety of approvals, including UL, CSA, TC, AWM, RoHS, CE and more. In the U.S., the National Electrical Code (NEC) sets the standards that designers must usually follow. These codes ensure that the cables have key performance features to satisfy machine requirements—for example, to stop the propagation of flames, satisfy the application’s maximum voltage draw, withstand extreme temperatures, and maintain integrity even when exposed to oil. THE BASICS OF MARY GANNON • SENIOR EDITOR • @DW_MARYGANNON INDUSTRIAL POWER TRANSMISSION CABLES REFERENCE GUIDE POWER TRANSMISSION Control cables, like this Chainflex continuous flex control design from igus, must be able to withstand high mechanical loads, speeds and accelerations. These Chainflex cables are intended for use in Energy Chain cable carriers and conform to key standards; are capable of torsion—depending on the cable; and can be used in high speeds and accelerations. They are UV resistant, flame retardant, halogen free, and can withstand very high or extremely low temperatures. They are available shielded or unshielded, with a choice of PVC, PUR and TPE outer jackets. Cabling_PTGuide_V2 MG.indd 32 4/29/16 11:15 AM
  35. 35. • Flexible Control Cables • Continous Flex Cables • Torsion Cables • Halogen-Free Cables • European Cables • Servo Motor Cables Bus Cables • Data Cables • Tray Cables • Silicone Cables • Cable Accessories • Specialty Cables • Stock Available for Immediate Delivery SAB NORTH AMERICA344 Kaplan Drive, Fairfield NJ 07004 Phone: 866-722-2974 • Fax: 973-276-1515 info@sabcable.com • www.sabcable.com C M Y CM MY CY CMY K SAB_PTGuide4-16.indd 33 4/29/16 10:06 AM
  36. 36. PowerTransmission REFERENCEGUIDE 34 DESIGN WORLD — MOTION 4 • 2016 motioncontroltips.com | designworldonline.com THE BASICS OF LISA EITEL • SENIOR EDITOR • @DW_LISAEITEL SPROCKETS & CHAIN DRIVES Shown here is an MPC sprocket from Martin Sprocket and Gear Inc. for use with a curvilinear timing belt. As a side note, synchronous belt drives work as a replacement for roller-chain drive systems where lubrication is unacceptable. ENGINEERS have used chains in motion systems for more than a century. They are versatile and reliable components to drive machinery and convey products. Now, advances in precision and technology let designers use chains in more applications than ever. Remote installations benefit from long-life chain that requires no lubrication, for example. Chain-based machinery abounds, but the most common industrial designs use roller chain. This type of chain consists of five basic components: pin, bushing, roller, pin link plate and roller link plate. Manufacturers make and assemble each of these subcomponents to precise tolerances and heat treat them to optimize performance. More specifically, modern roller chains exhibit high wear resistance, fatigue strength and tensile strength. Roller-chain applications generally fall into two categories: drives and conveyors. CHAIN-DRIVE APPLICATIONS Most typical drive applications use an ASME/ANSI roller chain wrapped around a driver sprocket (connected directly to the motor or reducer) and the driven sprocket (often connected to a machine’s conveyor head-shaft). This portion of the drive lets the designer build a system that’s either faster or slower by simply changing the ratio of teeth between the drive and driven sprocket. The ratio of the teeth determines the reduction in rpm … so to reduce rpm, the driven sprocket must be larger than the driver sprocket. For example, if the driver sprocket has 15 teeth and the driven sprocket has 30 teeth, the ratio is 2:1, so the rpm is halved at the driven sprocket. This Morse leaf chain from Power Transmission Solutions of Regal-Beloit America is made of roller-chain-type links and riveted pins for maximum strength for a given width. It works as tension linkage or a lifting device at slow speeds. ChainRollerSprockets_PTGuide_V3.indd 34 4/29/16 11:18 AM
  37. 37. CHAIN, ROLLER & SPROCKET 35DESIGN WORLD — MOTIONmotioncontroltips.com | designworldonline.com 4 • 2016 500 400 300 200 100 80 60 40 30 20 10 8 6 4 3 2 1 0.8 0.6 0.4 0.3 0.2 900 700 500 400 300 200 100 80 60 40 30 20 10 8 6 4 3 2 1 0.8 0.6 0.4 0.3 0.2 1,000 800 600 400 300 200 100 80 60 40 30 20 10 8 6 4 3 2 1 0.8 0.6 0.4 0.3 1,000 800 600 400 300 200 100 80 60 40 30 20 10 8 6 5 4 3 2 1 0.8 0.6 0.4 10 20 30 40 50 60 80 100 200 300 500 700 1,000 2,000 3,000 5,000 7,000 10,000 Roller-chaindrivecapacity(horsepower) Chain strands 4 3 2 1 25T 22T 19T 25T25T 25T 25T 25T 25T 25T 25T22T 21T 21T 21T 21T 21T 21T 19T 19T17T 17T 17T 17T 17T 19T 19T 19T 15T 15T 23T 23T 23T 23T 240200 180160140120100 80 60 50 40 35 Speed of roller chain’s small sprocket (rpm) Roller-chain selection chart This is a Zone Touch case conveyor from Container Handling Systems Corp. (CHSC), which uses chain drives that function as accumulating sections. It has longer life than conventional machines with rollers and fabric belts. It’s also quieter than roller conveyors because its tabletop chain rides low- friction UHMW wear strips and return ways. The easiest way to select a roller chain is using horsepower charts. First, obtain the motor horsepower and rpm of the small driver sprocket. From this, determine the chain size and number of teeth for the driver sprocket. Where roller chain must drive applications that need long life without contamination, pick chain with self-lubricating subcomponents. Where roller chain must drive applications that need high precision, pick chain with precision roller bearings at each link connection. CONVEYOR APPLICATIONS Conveyor chains come in myriad versions to move product horizontally, vertically or even around curved radii. The most common conveyor chains are ASME-style (ANSI-style) attachment chains. These chains include extended pins or plates with tabs onto which parts or product-holding shoes can bolt. Common versions are single-pitch attachment chain, double-pitch attachment chain, hollow-pin chain, curved- attachment chain and plastic-sleeve chain. The attachments let engineers put special fixtures or blocks onto the chain to serve specific conveyor functions. One subtype of conveyor chain is the accumulating conveyor. These stop discrete products even while the chain is still moving, and they do so with minimal friction and wear. Accumulating conveyors are suitable for applications (such as assembly lines) that have products ride through several stations. Tip: Select chain with top rollers or side rollers to let discrete products idle while the conveyor continues to run. Also pick custom attachments or work with manufacturers that make custom fixtures to handle specific parts. Many industries (including the automotive, food and beverage, and consumer-products industries) use custom attachments on their chain-based accumulator conveyors to economically and consistently move. CHAINS ENDURE SUBOPTIMAL ENVIRONMENTS The environments of many chain applications are less than ideal. Some require clean operation without the lubrication that can contaminate products. Others expose chain-driven machinery to weather, water or chemicals. So, chain manufacturers offer several products to meet these challenges. Consider roller chain: One critical area where roller chains need lubrication is the pin-bushing contact zone. Self-lubricating chains stay cleaner because the exterior of the chain is free of excess lube. These chains Morse inverted-tooth chain drives from Power Transmission Solutions of Regal-Beloit America come in HV versions for high capacity at high speed. Silent chain is another option to make smooth, silent drives at slower speeds. ChainRollerSprockets_PTGuide_V3.indd 35 4/29/16 11:19 AM
  38. 38. • Available from stock from over 30 Martin locations throughout North America • MTOs in days not weeks: » QD bushed » MST® bushed » Finished bore » Stainless steel » Aluminum » And more... • Over 350 MPC® SKUs on the shelf • Stocked in TB and Minimum Plain Bore • Compatible with all leading Curvilinear Belts Martin's MPC® Sprockets are manufactured in various sizes, dimensions and capacities to meet a variety of industrial requirements.These include a wide range of loads, speeds, and demanding applications such as blowers, conveyors, pumps and mixers. MPC ® SYNCHRONOUS SPROCKETS Direct drop-in for the most popular tooth profile martinsprocket.com • 817 258 3000 MartinSprockett_PTGuide4-16.indd 36 4/29/16 10:11 AM
  39. 39. CHAIN, ROLLER & SPROCKET 37DESIGN WORLD — MOTIONmotioncontroltips.com | designworldonline.com 4 • 2016 A1 chain (sometimes called B1 one-hole chain) has links with one hole and a bent attachment. A2 is similar but always double pitch with two attachment holes per link. K1 (B2 one-hole) and K2 (B2 two-hole) chains both have bent attachments on both sides. D1 (E1) and D3 (E2) chains have extended pins. Single-pitch WA1 (WCB1 one hole) chain and wide-contour WA2 (WCB1 two holes) chain both have bent attachments on one side and one or two holes per link. WSK1 (WCS2 one-hole or WM1) and WSK2 (WCS2 two holes or WM2) is wide-contour chain with straight attachments on both sides. WK1 (WCB2 one-hole) and WK2 (WCB2 two holes) is wide-contour chain with bent attachments. SK1 chain (sometimes called S2 one-hole or M1 chain) has straight attachments on both sides. SK2 (S2 two holes or M2) is the same but with two holes per link. SA1 (S1 one-hole or M35) chain and SA2 (S1 two holes or M35-2) chain both have straight attachments on one side, but the latter has two holes per link. Power-transmission and conveyor chain attachment options Roller-chain sprockets come in myriad versions, but most are shaft-ready designs. The sprocket here is from the Power Transmission Solutions division of Regal-Beloit America. also attract less dust and particulates than regular chains. Such roller chains are useful where oil contamination is a concern, including paper-product or wood-processing industries. SPECIALTY COATINGS AND STAINLESS STEEL CAN DELAY OR PREVENT CORROSION Nickel-plated chains offer another alternative for chain coatings, providing some protection for mildly corrosive environments. Stainless-steel chains offer superior corrosion resistance; however, designers must be aware that regular stainless steels cannot be hardened in the same manner as carbon steel. Therefore, the load carrying capacity of stainless steel is lower than carbon steel. Proper chain maintenance requires periodic inspection. All chains must be checked for damage, wear and chemical attack on a regular basis. Another issue is wear elongation. Eventually roller chains wear so much that they necessitate replacement—typically at 1.5 to 2% (12.180 in./ft to 12.240 in./ft) elongation. Chains may work until they reach 3% elongation, but are at increased risk for suboptimal performance. ChainRollerSprockets_PTGuide_V3.indd 37 4/29/16 11:19 AM
  40. 40. 38 DESIGN WORLD 4 • 2016 www.designworldonline.com PowerTransmission REFERENCEGUIDE COMPRESSION SPRINGS THE BASICS OF LISA EITEL • SENIOR EDITOR • @DW_LISAEITEL When hit by an object, oil inside this Zimmer shock absorber floods a spiraling channel from its fat opening to its narrow end. Sold by Intercon Automation Parts, the shock absorber relies on compression springs to return to its extended position after each cycle. ENGINEERS incorporate compression springs in designs that need linear compressive forces and mechanical energy storage— designs such as pneumatic cylinders and push-button controls, for example. The most conventional compression spring is a round metallic wire coiled into a helical form. The most common compression spring, the straight metal coil spring, bends at the same diameter for its entire length, so has a cylindrical shape. Cone-shaped metal springs are distinct in that diameter changes gradually from a large end to a small end; in other words, they bend at a tighter radius at one end. Cone-shaped springs generally go into applications that need low solid height (the total height when compressed) and higher resistance to surging. Whether cylindrical or cone shaped, helical compression springs often go over a rod or fit inside a hole that controls the spring’s movement. Other configuration types include hourglass (concave), barrel (convex), and magazine (in which the wire coils into a rectangular helix). Most compression springs have squared and ground ends. Ground ends provide flat planes and stability under load travel. Squareness is a characteristic that influences how the axis force produced by the spring can be transferred to adjacent parts. Although open ends may be suitable in some applications, closed ends afford a greater degree of squareness. Squared and ground end compression springs are useful for applications that specify high-duty springs; unusually close tolerances on load or rate; minimized solid height; accurate seating and uniform bearing pressures; and minimized buckling. The key physical dimensions and operating characteristics of these springs include their outside diameter (OD), inside diameter, wire diameter, free length, solid height, and spring rate or stiffness. • Free length is the overall length of a spring in the unloaded position. • Solid height is the length of a compression spring under sufficient load to bring all coils into contact with adjacent coils.
 • Spring rate is the change in load per unit deflection in pounds per inch (lb/in.) or Newtons per millimeter (N/ mm). The dimensions, along with the load and deflection requirements, determine the mechanical stresses in the spring. When the design loads a compression spring, the coiled wire is stressed in torsion and the stress is greatest at the wire surface. As the spring is deflected, the load varies, causing a range of operating stress. Stress and stress range affect the life of the spring. The higher the stress range, the lower the maximum stress must be to obtain comparable CompressionSprings_PTGuide_V2.indd 38 4/29/16 11:21 AM
  41. 41. RotorClip_PTGuide4-16.indd 39 4/29/16 10:12 AM
  42. 42. 40 DESIGN WORLD 4 • 2016 www.designworldonline.com PowerTransmission REFERENCEGUIDE life. Relatively high stresses may be used when the stress range is low or if the spring is subjected to static loads only. The stress at solid height must be low enough to avoid permanent damage because springs are often compressed solid during installation. HOW TO SELECT COMPRESSION SPRINGS Here are the most important factors to consider when selecting helical compression springs. The OD of a spring expands under compression. Be sure to consider this if the spring goes into a tube or a bore during assembly. Also remember that the OD of a spring is subject to manufacturing tolerances, just as any mechanical part. If the tolerance range is positive, the spring’s dimensions may be slighter larger and can add to the overall assembly’s envelope size. Most spring suppliers specify work-in-hole diameters for their springs to factor in manufacturing tolerances and the OD’s expected expansion. Look for this information to quickly select from stock spring catalogs, or use this information to better communicate product needs when ordering custom-made springs. Consider loading or travel requirements on the compression spring. The spring rate (also called the spring constant) is the relationship of the force to compress a spring by a unit of length, typically pounds per inch. So with a given load, the product designer can calculate expected spring travel. The further the spring travels, the more stress it endures. So at a critical point, stress can yield the wire material … causing a phenomenon called spring set. After spring set, the spring can’t expand back to its original unloaded length. Even so, in some assemblies, such springs can still function. Stress formulas and online calculators predict spring set. Otherwise, a starting rule of thumb is to avoid solid height by at least 20% (so that there’s always 20% of the spring’s total travel left during the normal range of operation). Compression spring-end types are standard or special. Standard ends are either plain open or closed. Either can be ground or not ground. The ends actually affect the spring rate. So, springs with dissimilar ends that are otherwise identical (with the same total coils, wire size, and OD) have different spring rates. Ground ends require more manufacturing effort. However, combined with closed ends, round ends improve the squareness of the loading force and reduce spring-buckling tendencies. Some manufacturers include closed and ground ends in standard catalog stock design, while some don’t. Be sure to know the difference. Special end examples include reduced coil for screw mounting, offset legs to work as alignment pins, and enlarged coils to snap into ring grooves. Spring materials abound and include everything from carbon steel to exotic alloys. Music wire is a high-carbon spring steel and is the most widely used material. Stainless steel 302 has less strength than music wire, but adds general corrosion resistance. Nickel alloys make a lot of springs branded under various trademarks and are chosen for extreme high or low operating temperatures, specific corrosive environments, and non-magnetic qualities. Springs made of phosphor bronze and beryllium copper are copper alloys for good corrosion resistance and electrical conductivity. This concave (hourglass-shaped) compression spring can stay centered, even in large-diameter bores. Surging is when a spring builds compression-wave motion when subject to vibrations close to its natural frequency. This cone-shaped compression spring resists surging. The larger outer coils collapse before the smaller inner coils, so forces on the spring also increase the spring rate for a natural damping effect. Photo courtesy Lee Spring. This compression spring has reduced ends. This compression spring has a barrel shape for lateral stability. CompressionSprings_PTGuide_V2.indd 40 4/29/16 11:21 AM