linear cutting processes (shaper, planer, slotter, broaching and sawing)

1. Shaper, Planer, Slotter, Broaching and Sawing

2. • Tool has reciprocating motion.
• Workpiece is clamped on the table which is
stationary.
Shaper
A Machine which produces flat surfaces

3.  Tool should be firmly supported during the forward motion to carryout the material removal.
 Tool is lifted during the return stroke since it will not be doing the cutting.
 Clapper box arrangement is used for the purpose
 The Shaper is a relatively slow machine tool with very low metal removal capability.
 It uses a single point tool similar to a lathe which is clamped to a tool post mounted to a clapper
box which in turn is mounted to a reciprocating ram
 Cutting takes place only in forward direction
Shaper

4. Shaper
RATCHET AND
PAWL Mechanism
Crank and Slotted lever quick
return mechanism

5.  The major motions required in shaper are the
reciprocating motion of the cutting tool and the
auxiliary motion.
 During the forward motion of the tool cutting is
performed while during the return stroke the tool will
simple be sliding.
 This is generally accomplished by means of a quick
return mechanism.
Shaper
Crank and Slotted lever quick return
mechanism

6.  In extreme positions AP1 and AP2 are tangential to
circle and cutting tool is at the end of stroke.
 Forward stroke occurs when crank rotates from
position CB1 to CB2 through angle β in clockwise
direction.
 The return stroke occurs when crank rotates from
CB2 to CB1 through angle α in clockwise direction.
Since tool travels a distance of R1R2 during cutting
and return stroke. So length of stroke is
Crank and Slotted lever quick return mechanism
Crank and Slotted lever quick
return mechanism

7. Whitworth quick return motion mechanism

8.  The feed screw is engaged by a pawl that sits in a
notched wheel attached to the feed screw.
 The pawl operates once for each of the rotation of the
bull gear.
 During one revolution of the bull gear, the oscillating
motion of the pawl carrier moves the pawl forward
and then back by one or more teeth depending upon
the feed rate that was set.
Mechanical Feed drive
Shaper
RATCHET AND PAWL Mechanism

9.  The mechanical shaper has the problem of inertia
of the main drive components, which require some
time for reversal for every stroke and as a result, a
large proportion of time is spent with the tool
cutting air.
 Simple hydraulic circuit to provide the reciprocating
motion overcomes this problem
 Cutting speed remains constant throughout most
of the cutting stroke unlike the crank shaper where
the speed changes continuously.
 Since the power available remains constant
throughout, it is possible to utilise the full capacity
of the cutting tool during the cutting stroke.
 The ram reverses quickly without any shock due
the hydraulic cylinder utilised.
 The range and number of cutting speeds possible
are relatively large in hydraulic shaper.
 More strokes per minute can be achieved by
consuming less time for reversal and return
strokes.
Hydraulic Shaper
Shaper
Advantages

10. Shaper
Machining Horizontal Surfaces
Machining Vertical Surfaces
Machining Angular Surfaces
Cutting Rack or Splines
Cutting Key ways (At the end)

11. SHAPING AND PLANING
Components of a slotter machine.
 Identical machine to a horizontal shaping
machine but inclined 90º.
 It allows a higher cutting power as the
workpiece is better hold on the working
table.
Components of a shaper.
 Tool has reciprocating motion.
 Workpiece is clamped on the table
which is stationary.
Shaping
(HORIZONTAL)
SHAPING MACHINE
VERTICAL SHAPING MACHINE
OR SLOTTER MACHINE

12. SHAPING AND PLANING
Components of a planer.
Parts made by a shaping and planing.
 Tool is stationary.
 Workpiece is clamped on the table which
has reciprocating motion.
 It allows machining of much larger parts.
Planing

13. Planner machines
• Tool is stationary.
• Workpiece is clamped on the table which has
reciprocating motion.
• It allows machining of much larger parts.

14. Slotter machine
• Identical machine to a horizontal shaping
machine but inclined 90º.
• It allows a higher cutting power as the
workpiece is better hold on the working
table.

15. Comparison of shaper, planer and Slotter machine

16. BROACHING

17.  It is a machining process that uses a multiple-tooth cutting tool, called broach, moved linearly relative to
the workpiece. Each tooth is successively higher than the previous tooth.
 The material is removed in one stroke (pulling or pushing) (main difference in comparison with
shaping and planing).
 Most broaches are made of HSS, although carbide inserts (brazed or mechanically attached) also exist.
 It works best on soft materials: aluminium, bronze, brass, wood, plastics, composites, graphite,…
•
 Dimensional tolerance ~ IT6
Advantages:
 Suitable for mass production.
 Cutting time is quick.
 Variety of work shapes possible.
Disadvantages:
 Owing to complicated and often
custom-shaped geometry, tooling is
expensive.
 Valid only for light cuts.
 Only through hole and surfaces can be
machined.
BROACHING

18. BROACHING
Parts made by surface broaching Surface broaching machine
VIDEO VIDEO
Surface broaching
 It is used to cut flat surfaces.
 The tool is a simple flat bar with multiple rows of cutting teeth.
 Surfaces may be flat, concave, convex, serrated or cam-shaped.
VIDEO

19. Internal broaching
 It is used for enlarging long holes.
 A starting hole must be predrilled in the part to insert the broach at the beginning of the stroke.
BROACHING
Typical parts made by internal broaching
Internal broaching machine
VIDEO VIDEOVIDEOVIDEO

20. Internal broaching
Surface broaching

21. SAWING

22. SAWING
 Sawing consists in cutting a narrow slit in a workpiece using a tool consisting of a series of
narrowly spaced teeth.
 The tool is called a saw blade and the teeth are typically made of carbon steel, HSS, carbide or
diamond.
Typical functions:
 Separate a workpart into two pieces.
 Cut off unwanted portions of part .
Teeth are deviated in order to reduce friction
between saw blade and part.

23. Teeth type depending on the cutting material
SAWING
HSS teeth
welded on a steel blade
Carbide inserts
brazed to blade teeth
50 HRC

24. SAWING
Manual hacksaw
Circular saw
Hacksaw or reciprocating
saw machine
Band saw machine
HORIZONTAL VERTICAL
Sawing machines
VIDEO
VIDEO
VIDEO
VIDEO
VIDEO
VIDEO

25. Examples of various sawing operations.
SAWING
Sawing operations

26. In a crank and slotted lever quick return motion
mechanism, the distance between the fixed
centres is 300 mm and the length of the driving
crank is 150 mm. Find the inclination of the
slotted bar with the vertical in the extreme
position and the time ratio of cutting stroke to
the return stroke.
If the length of the slotted bar is 600 mm, find
the length of the stroke if the line of stroke
passes through the extreme positions of the free
end of the lever.
Numerical-Shaper