Shaping, Planing
and Slotting
Operations
Chapter 7
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Production of Flat
Surfaces
Typical components with flat surfaces
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Production of Flat Surfaces..
Cut
E
A'
A
Fe
ed
B'
B
C
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Depth
of cut
Motions for producing Flat Surface
D
e
c
e
i
p
Work
Reciprocating Machine
Tools
• different from rotary machine tools
• A single-point tool moves linearly
relative to the work part
• Shaper Shaping tool moves
• Planer Planing workpiece moves
• Slotter
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Shaper/Shaping
Machine
Shaper/
Tool head
d or f
Tool
Workpiece
Vise
Table
f or d
Ram v
Base
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Column
Shaper/Shaping
Machine
Shaper/
Main Parts
Base
Column – drive, support & guide ram
Table – hold & feed workpiece
Ram – tool head, clapper box
Types of Shaping M/c
• Horizontal Shaper
• Vertical Shaper (Slotting M/c)
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Shaping Operation
Cutting action and functioning of
clapper box in a shaper
Clapper box
Tool cleared
from machined
surface
Lifted
clapper
box
Workpiece
(a) Forward/Cutting stroke
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(b) Return stroke
Shaping Operation..
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Shaping Operation ..
Machining of inclined surface on shaping
machine
Tool head & slide
(axis parallel to
machined surface)
Clapper box
(axis away from
toolhead)
θ
Movement
of the slide
for feed
Inclined
machined
surface
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Tool holder
located at a
convenient angle
Tool
θ
Workpiece
Depth of cut
Operating Conditions in a
Shaping Machine
N L (1 + m)
cutting speed v =
1000
m/min
where
N = the number of double strokes or cycles
of the ram per min (one double or full stroke
= one cutting and one return stroke)
L = Length of the ram stroke in mm
m = return stroke time/cutting stroke time
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Operating Conditions in a
Shaping Machine ..
Cutting Stroke
Return Stroke
Workpiece
c
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Lj
c Clearance
Length of stroke L
Length of Stroke L = Lj + 2 c
Operating Conditions in a
Shaping Machine ..
Feed f
• Feed f is the relative motion of the
workpiece in a direction perpendicular
to the axis of reciprocation of the ram
• Feed is expressed in mm/double stroke
or simply mm/stroke because no cutting
is done in return stroke
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Operating Conditions in a
Shaping Machine ..
Depth of Cut d
• Depth of cut d is the thickness of the
material removed in one cut, in mm
• Depth of cut may be given by the tool
head slide or by lifting the table
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Machining Time
f
w
mm
mm
L mm
Width cut in 1 stroke = f
Total width = w
No. of strokes to m/c total surface = w/f
Strokes/mm = N
Time for machining surface is
t = w/(f N) min
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Machining Time
Time for machining w x L surface
w
t=
fN
min
From cutting speed
N L (1 + m)
1000 v
v=
⇒N =
1000
L(1 + m)
Machining time
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w
L w (1 + m)
t=
=
f N
1000 v f
min
Material Removal Rate
• Material removal rate (MRR)
MRR = f d L N(1+m) mm3/min
where d is depth of cut in mm
f is feed in mm/stroke;
N is strokes/min
L is length of stroke in mm
m is ratio of return stroke time to
cutting stroke time
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Planer
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Planer/Planing Machine
Housing
Tool heads
Tool head
Reciprocating
table
Bed
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Guideways
Tool head
Types of Planing Machines
• Open Side Planer
• Double Housing Planer
• Edge planer
• Universal planer,
• Pit type planer
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Operating Conditions in a
Planer
• Operating conditions in planer are
similar to Shaping Machine
Cutting Speed: Workpiece reciprocates
cutting time=return time
Cutting Tool: Multiple cutting tools cut
simultaneously
Job: Large size or multiple workpieces
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Size of Shaping and Planing
Machines
• Largest Size of Workpiece that can
be Machined
Lxwx h
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Difference between Shaper and
Planer
•
•
•
•
•
Size of Workpiece
Movement of Tool and Workpiece
Construction
Cutting and Return Speeds
Number of toolheads
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Slotting
Slot made
by slotting
Ram
Tool
Table
Typical Job
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Column
Tool
holder
Base
Slotter/Slotting Machine
Example 7.1
Find the machining time required for machining
the surface 600 × 800 mm, on a shaping
machine. Assume, cutting speed as 8 m/min.
The return to cutting time ratio is 1:4, and the
feed is 2 mm/double stroke. The clearance at
each end is 70 mm.
• Solution
Lj = 600 mm, w = 800 mm, v = 8 m/min,
m = ¼, f = 2 mm/stroke, c = 70 mm
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Example 7.1 ..
• Given clearance at each end: c=75 mm
• length of stroke:
L = 600 + 2×70 = 740 mm
N L (1 + m)
1000v
v=
⇒N =
= 8.65 strokes/min
1000
L(1 + m)
Assume 8.65 strokes/min available
• Machining time for 800 mm width
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w
t=
= 46.25 min
f N
Example 7.1 ..
• Alternately:
L w (1 + m)
t=
1000 v f
740 × 800 × (1 + 0.25)
=
1000 × 8 × 2
= 46.25 min
Assumptions:
N?
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Examples
• Example 7.2: Estimate the time required to
machine a cast iron surface 250 mm long and
150 mm wide on a shaper with cutting-toreturn ratio of 3/2. Use a cutting speed of 21
m/min, a feed of 2 mm/stroke and a clearance
of 25 mm. The available ram strokes on the
shaper are: 28, 40, 60 and 90 strokes/min.
Also, determine MRR assuming depth of cut
as 4 mm.
• Solution
• Given data: Lj = 250 mm, f = 2 mm/double
stroke, w = 150 mm,
•
c = 25 mm, v = 21 m/ m/min, d = 4 mm
• The cutting-to-return ratio of 3/2 gives m = 2/3
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Examples
• Given clearance is 25 mm, hence,
•
L = 250 + 2 × 25 = 300 mm.
• We know that (Equation (1))
• SPEED v = NL(1+m)/ 1000
m/min
•
From the above equation, we find
number of double strokes N per minute
required as
•
N = 42 strokes/min
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Examples
• Nearest available ram strokes is 40
strokes/min. Since calculated value is more
than 40, this is chosen. Normally, we should
not exceed the specified cutting speed, as it
will affect the tool life adversely. Hence,
select N = 40 strokes/min.
• With a chosen value of N, we cannot use
Equation (5) for time calculation. Hence,
substituting all the values in Equation (6),
we get
•
t = 150 / (40×2)
•
= 1.88 minutes
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