1. Why (and how) You Should
Implement Plastic Bearings

2. Before We Start
 This webinar will be available afterwards at
designworldonline.com & via email
 Q&A at the end of the presentation
 Hashtag for this webinar: #DWwebinar

3. Presenters
Moderator
Leslie Langnau
Matt Mowry
Design World
igus
Nicole Lang
Donna Meyer
igus
University of Rhode
Island

4. Why (and how) to
implement plastic
bearings into your
application.

5. • Development
• Advantages
• Simple polymers vs. composite
polymers
• Selection criteria

6. Polymers in general
•
•
•
•
Natural polymer lubricants
Oils and greases
Incorporated into solids
Plastics and rubbers

7. Why use polymer bearings?
•
•
•
•
Fluid lubricants not effective
Fluid lubricants not safe
Maintenance issues
Insufficient boundary lubrication

8. Possible environments
MARINE: seawater and fresh water

9. Possible environments
AGRICULTURE: moisture, chemicals, dirt

10. Possible environments
MEDICAL: equipment, implantable devices

11. Possible environments
PACKAGING: food and pharmaceuticals

12. Simple polymers
Stachowiak & Batchelor,, Engineering Tribology, 2005, 3rd Ed., Elsevier Inc., Chp. 16, Fig.16.1, pp. 653.
Bunn & Howells, (1954), “Structures of Molecules and Crystals of Fluorocarbons”, Nature, 174, pp. 549-551.
Makinson & Tabor, (1964), “The Friction and Transfer of Polytetrafluoroethylene”, Proc. Roy. Soc. (A), 281, pp. 49-61.

13. Simple polymers
Ludema, Friction, Wear, Lubrication: A Textbook in Tribology, 1996, CRC Press, Chp. 8, Fig. 8.15, pp.143.
Stachowiak & Batchelor,, Engineering Tribology, 2005, 3rd Ed, Elsevier Inc., Chp. 16, Fig. 16.3, pp. 655.
Makinson & Tabor, (1964), “The Friction and Transfer of Polytetrafluoroethylene”, Proc. Roy. Soc. (A), 281, pp. 49-61.

14. Limitations of simple polymers
•
•
•
•
•
High wear rates
Frictional heating
Solvent damage
Soft – easily deforms
Mostly low loads
Stachowiak & Batchelor,, Engineering Tribology, 2005, 3rd Ed, Elsevier Inc., Chp. 16, Figs. 16.7, 16.9, and 16.26, pp. 657-672.
Arnell, Tribology: principles and design applications, 1991, Macmillan, pp. 110.
Khonsari,& Booser, Applied Tribology: Bearing Design and Lubrication, 2008, Wiley & Sons, pp.97.

15. Composite polymers
• Improved mechanical strength
• Improved wear resistance
• Reduce coefficients of friction
Stachowiak & Batchelor,, Engineering Tribology, 2005, 3rd Ed., Elsevier Inc., Chp. 16, Fig.16.29, pp. 677.
Tsukizoe & Ohmae, Friction and Wear of Polymer Composites,1986, K. Friedrich, Ed, pp.205-231.

16. Composite polymer bearing
Base polymers are
responsible for low
coefficients of
friction.
Fibers and filler materials
reinforce the bearing and
allow for high forces or edge
loads on the bearing.
Solid lubricants lubricate the
system independently,
mitigating friction and
reducing wear rates

17. Advantages of composite polymers
•
•
•
•
Improve mechanical and thermal properties
Addition of reinforcing fibers and fillers
Reduce wear rates
Effective under high and low loads

18. More advantages . . .
•
•
•
•
•
•
•
Low friction coefficients with mating materials
Inert
Biocompatible
Self-lubricating
Serve as reservoir for boundary lubricants
Tune material properties
Make into any shape: molding or machining

19. Selection criteria
•
•
•
•
•
•
Maximum load
Sliding speed
Environmental conditions
Counterface roughness
PV limit
Wear factor k
Stachowiak & Batchelor,, Engineering Tribology, 2005, 3rd Ed, Elsevier Inc., pp. 658-659.
Arnell, Tribology: principles and design applications, 1991, Macmillan, pp. 1111-112.
Khonsari,& Booser, Applied Tribology: Bearing Design and Lubrication, 2008, Wiley & Sons, pp. 356-358.
Blanchet, (1997), ‘‘The Interaction of Wear and Dynamics of a Simple Mechanism,’’ ASME J. Tribol., 119, pp. 597–599.

20. Composite plastic bearings vs.
- simple plastic bearings
- bronze bearings
- PTFE-lined, metal-backed bearings
- ball bearings

21. Composite plastic bearings vs.
simple plastic bearings
• Composites enhance the benefits of plastics
•
Base materials
•
Fillers - increase load capacity
•
Solid lubricants - reduce friction

22. Composite plastic bearings vs.
simple plastic bearings
Polyamide 6.6
100
Polyamide 6.6
100
Polyacetal (POM)
90
Polyacetal (POM)
90
igus L280
70
60
80
igus H370
igus J
80
70
igus L280
60
igus J
igus H370
50
50
40
40
30
30
20
20
10
10
0
0
material
material
Friction
Wear
Parameters: P = 0.7 N/mm2, v = 0.15 m/s, case-hardened steel shaft

23. Composite plastic bearings vs.
bronze bearings
• 1930’s technology
• High speed and rotational movement necessary to
draw oil out and create a lubricant film
• Shaft oscillation, slow speed, linear and
intermittent use can all inhibit this process
“Shaft oscillation or slow speed, intermittent use, pulsating or
uneven loads are conditions that inhibit full-film lubrication
from developing or being maintained” – from oilite
manufacturer’s product information

24. Composite plastic bearings vs.
bronze bearings
Bronze bearings:
+ low coefficient of friction (if maintained)
+ slightly more precise (low thermal expansion)
+ high speeds are possible
+ high p x v value
- limited application temperatures
- poor chemical/corrosion resistance
- not ideal in dirty environments
- must be reamed at install
- unsuitable for linear motions
- low impact load capability

25. Composite plastic bearings vs.
bronze bearings
Composite plastic bearings:
+ higher load possible
iglide® composite bearing: <21,500 psi
bronze bearing: <8000 psi
+ no external lube or maintenance required
+ better in aggressive environments
+ ideal for rotating, pivoting and linear use
+ great for impact loads and high-vibrations
+ can use non-hardened shaft materials
+ lightweight

26. Composite plastic bearings vs.
bronze bearings
better lifetime than bronze
grease and oil-free
dirt and dust resistant
ideal in pivoting/intermittent
applications
• increased lifetime
• easy to assemble (no reaming)
• better suited for impact loads
•
•
•
•

27. Composite plastic bearings vs.
PTFE, metal-backed bearings
• 1950’s technology
• steel/bronze outer layer is rolled
• ID contains thin layer of bronze
• Impregnated with PTFE and lead

28. Composite plastic bearings vs.
PTFE, metal-backed bearings
PTFE, metal-backed bearings:
+ good thermal conductivity/heat dissipation
+ ability to withstand high operating temperatures
+ max speed 1,000 fpm
+ PV 50,000 psi/fpm continuous
+ PV 100,000 psi/fpm short term
- thin wear surface
- corrosive
- contain lead
- heavier than plastic bearings
- difficult installation procedures

29. Composite plastic bearings vs.
PTFE, metal-backed bearings
Composite plastic bearings:
+ Suitable for a wide range of applications
+ Dimensionally Interchangeable
+ More wear surface
+ Lightweight
+ Corrosion-Resistant
+ Better for dirty environments
+ Predictable lifetime

30. PTFE-lined vs. iglide® bearing - wear
Oscillating movement
5
4.5
4
3.5
3
igus J
igus L280
igus Z
PTFE-Lined
2.5
2
1.5
1
0.5
0
HC AL
Case-HardSteel
Machine Grade
304SS
Parameters: Pressure = 1 MPa, Velocity = 0,01 m/s

31. PTFE-lined replaced with composite plastic
“iglide® bearings cost slightly less, but the most
important advantage is that they don’t need to be
replaced by riders. They last for the entire life of our
pedals.”
•
•
•
•
dirt and dust resistance
lightweight
corrosion resistance
proven to require less maintenance than the alternative
in this application, plus a longer life

32. Recirculating ball bearings
• Balls run through a linear raceway
• Contain a lubrication-bath
• May require constant maintenance
• Additional components are often
required: Zerks, lube lines, seals, etc.
with plastic
spacers
standard version: one
ball pushes the next

33. Recirculating linear ball bearings
+ higher combination of dynamic load vs. speed
+ high precision possible (micron level)
+ low friction (if properly maintained)
+ suitable for highly cantilevered loads
- expensive
- must be lubricated/maintained
- require hardened steel shafting
- poor in dirty environments
- not ideal for clean applications
- limited accelerations possible

34. Plastic linear bearings
+ lower cost of ownership
+ suitable for harsh environments (dirt, chemicals, water)
ideal for high-impact loads (shocks/vibrations)
+ higher static loads than ball bearings
+ suitable for soft shafting (aluminum/300-SS)
+ suitable for short strokes
+ quiet/lightweight

35. Recirculating ball bearings replaced
Vertical-Form-Fill-Seal
packaging machine:
Welding jaws
+ Increased machine’s
cycles-per-minute by 20%
+ Ball bearings limited by
accelerations and bad
environments
+ Lower cost than ball
bearings

36. Implementing
iglide® plastic
bearings in your
application

37. iglide® plastic bearings
•
Check temperature, static-surface pressure, speed.
•
Max. P x V value is  28 571 Psi * fpm in a permanently dry-running application.
•
Typical application involves low speeds < 60 fpm or high loads up to 14,500 psi
(rotating oscillating.)
•
Use hardened shaft in applications > 700 psi
•
When the total sliding distance is less than 6,000 miles
•
Use a clearance of 0.002” – 0.004” (0.05 - 0.10 mm)

38. PV Value
•
In a plain bearing, friction heat is created when the shaft moves inside the
bearing.
•
We determine p*v by the values present in the application for pressure and
speed.
•
By multiplying these two factors we find the p*v (measure for the amount of
heat created):
o Pressure in psi
o Velocity in fpm

39. PV Value
2 ways to dissipate the heat from the bearing:
Via the bearing into the housing
Via the shaft outside the bearing

40. Factors influencing PV
•
Thermal conductivity of shaft, housing and bearing material.
•
Coefficient of friction.
•
Maximum temperature limit of the bearing material.
•
Ambient temperature in the application.
•
Wall thickness of the bearing and length.

41. The 2:1 Rule

42. Other considerations
•
•
•
•
•
•
•
Shaft material
Shaft roughness
Shaft hardness
Housing material
Environment
Chemicals
Certifications (ex. FDA compliance, UL94 horizontal burn test etc.)

43. What is iglide®?
iglide® bearings are engineered plastics
 More than 30 iglide® materials:
 iglide® bearings are available in more than 30
tribopolymers to meet your specific needs.
 More than 150 additional materials for special
custom requests or needs.
 All tested and predictable.
more than 30 dry-tech
tribopolymer materials
dry-tech

44. The igus® test facility
Over 10,000 plastic
bearing tests annually
Focus on coefficients of friction and wear under all possible conditions and
at a wide range of speeds. Factors such as dirt and climate also tested.

46. Founded: October 1964, Cologne Germany
Approx. 1,600 employees in inland and overseas
28 igus® subsidiaries worldwide and distributors in more
than 42 countries.
Product groups:
- Energy Chain® cable carriers
- Chainflex® continuous-flex cables
- ReadyChain® pre-harnessed systems
- iglide® polymer plain bearings
- igubal® self-aligning plastic bearings
- DryLin® linear bearings
igus®, Inc.
•US, Canada, Mexico
•More than 50 Sales Engineers Throughout North America and in
our Rhode Island office available for support
•Available for visits within 24-48 hours
•Stock held in East Providence, RI
•No Minimum Orders
•Over 10,000 sizes available in stock ready to ship within 24 hours

47. Contact Us
sales@igus.com
Tel. (800) 521-2747 or (401) 438-2200
Twitter: http://www.twitter.com/igus_Inc
http://www.igus.com

48. Questions?
Design World
Leslie Langnau
LLangnau@wtwhmedia.com
Phone: 440-234-4531
Twitter: @DW_RapidMFG
igus
Matt Mowry
Mmowry@igus.com
Phone: 888-803-1895 ext. 140
Twitter: @igus_inc
University of Rhode Island
Donna Meyer
dmmeyer@egr.uri.edu
igus
Nicole Lang
Nlang@igus.com
Phone: 888-803-1895 ext. 111
Twitter: @igus_inc

49. Thank You
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