Chapter 4.pdf - Zagazig University Staff Home Page

Production Engineering (1) 

Chapter 4 

Dr. Mahmoud M. Atta 

Shaping, Planning and Slotting 

Processes for machining horizontal, vertical and inclined flat and 

contoured surfaces, slots, grooves and other recesses by meansof 

special single point cutting tools. 

The cutting is intermittent. 

Surface produced by a shaper 

(a) Grooved 

block 

(b) Dove 

tail slide 

(c) Guide gib 

(d) V-Block 

(e) Tee slot 

Fall 2012 EngM 324 

1




Difference between the three types 

Shaper Planer Slotter 

1 

The work is stationary and the The tool is stationary and the The work is held stationary and the 

tool on the ram is moved back workpiece on the table travels tool on the ram is moved up and 

and forth across the work. back and forth under the tool down across the work. 

2 

Used for shaping much smaller 

jobs 

Meant for much larger jobs. 

Jobs as large as 6 metre wide and 

twice as long can be machined. 

It is used for making slots in 

smaller jobs. 

3 Is a light machine It is a heavy duty machine. Slotting is light machine 

4 

Can employ light cuts and finer 

Can employ heavier cuts and 

Can employ light cuts and finer 

feed. 

coarse feed. 

feed. 

5 

Uses one cutting tool at a time 

Several tools can cut 

simultaneously. 

Shaper uses one cutting tool at a 

time 

6 

Driven using quick- return link 

mechanism 

The drive on the planer table is 

either by gears or by hydraulic 

means 

The rams are either crank-driven 

or hydraulically driven. 

7 

It is less rigid and less robust 

Better rigidity that give more 

accuracy on machined surfaces. 

It is less rigid and less robust 


2




a) Shaping b) Planning c) Slotting 


3




Shaping 

Specification of shaper 

1. Maximum ram stroke (mm) 

2. Work table surface (W*L) 

3. No. of stroke per min (st/min) 

4. Motor power (KW) 

(1) The column 

(2) the motor 

(3) the ram 

(4) the table 

(5) The tool head 

(6) clapper box 

(7) The slot with the clamp. 

(8) The tool slide and feed screw handle. 

(9) Ratchet and pawl mechanism 

(10) the elevating screw of the table. 

(11) Support bracket 

(12) The levers for setting (st/min) 


4





5




Specification of planer 

1. Max. Workpiece dimension (W*L) 

2. Table speed (m/min) 

3. Vertical tool feed per stroke (mm) 

4. Table motor power (KW) 

Planer 


6




Specification of slotter 

1. Maximum ram stroke (mm) 

2. Work table diameter (mm) 

3. Max distance between tool post 

to bed (mm) 

4. Max distance between ram guide 

and work table (mm) 

5. Motor power (KW) 

Slotter 


7




Quick-return mechanisms 

These types of machine tool are of rectilinear cutting motion 

therefore, the rotary motion of the drive is converted into 

reciprocating motion. 

The metal is removed in the forward cutting stroke, while the 

return stroke goes idle and no metal is removed during this 

period. 

The cutting mechanism is so designed that it moves at a 

comparatively slower speed during forward cutting stroke, 

whereas during the return stroke it allow the ram to move at a 

faster speed to reduce the idle return time. 

This mechanism is known as quick return mechanism. 


8




The reciprocating movement of the ram and the quick return 

mechanism of the machine are generally obtained dby anyone 

of the following methods: 

1. Lever rocker arm mechanism (shaper). 

2. Slider crank mechanism (slotter). 

3. With worth quick return mechanism (shaper and slotter). 

4. Hydraulic system ( all the 3 types). 

5. Variable speed reversible motor (slotter and planer). 

6. Rack and pinion mechanism (planer). 


9




Hydraulic system 

Its advantages; 

1. Greater flexibility of speed (infinite variable) 

2. Smoother in operation 

3. Ability to slip in case of overload, thus eliminating tool and 

machine damage 

4. Possibility of changing speeds and feeds during operation. 

5. Providing a constant speed all over the stroke. 


10




Rack and pinion mechanism 


11




Lever rocker arm mechanism 

1. Speed adjustment 3. Stroke position adjustment 

2. Stroke length adjustment 4. Quick return action 


12




Quick return action 

Cutting ration = 

Time for cutting stroke 

Time for return stroke 

= t C 

t R 

= 

Angle of cutting stroke 

Angle of return stroke 

θ C 

= 

θ 

= 1 m 

θ R 

The length of the stroke is reduced the quick return 

The length of the stroke is reduced the quick return 

action (inverse proportional). 


13




Feed Mechanism 

1. Driving disc 

2. Driving pin 

3. Connecting link 

4. The pawl carrier 

5. Pawl 

6. The ratchet wheel 

How to reverse the direction of the machine table and to make 

the feeding rate zero. 


14




Tool mounting 

Tool head 

Back block 

Tool post 


15




Work holding devices 


16




Machining time 

W. 

i 

NL( 1+ 

m) 

T m = 

V c = 

f . N 

1000 

N 

1000 

V 

= Vc = 

VR 

* m 

2. 

L s 

V is the average cutting speed 

V c is the mean cutting speed 

V R is the mean return speed 

W = w + w 1 + w 2 

m is the inverse of the cutting ratio 


17




Example 

It is required to machine three slots, in a workpiece, of 20 mm. wide 

and 30 mm. height by ashaping machine. The stroke length is 450 

mm. the shaper makes 30 stroke/min with feed rate 0.25 mm/stroke 

and cutting angle 210º. Take the depth of cut equal 5 mm. 

Calculate: 

1) Average cutting and return speeds. 

2) The machining time. 

3) How can the feed adjusted if the shaper table cross slide lead 

screw has 5 mm. pitch and tooth wheel of 75 teeth. 


18

JAZAN UNIVERSITY 

COLLEGE OF ENGINEERING 

MECHANICAL ENGINEEING DEPARTMENT 

PRODUCTION ENGINEERING (1) (ENGM324) 

SHEET 3 

1. Mention, with neat sketch, the different surfaces produced with shaper. 

2. Make a comparison between shaping, planning and slotting processes. 

3. Discuss 3 different methods used to produce quick return action in shaper, 

planer or sloter. 

4. What is the advantage of the hydraulic system when used as quick return 

mechanism? 

5. Show how to adjust the stroke length and stroke position in lever rocker arm 

mechanism 

6. Describe the quick return action in Lever rocker arm mechanism. 

7. Describe the feed mechanism in shaper and show how to reverse the feed 

direction. 

8. Show how to produce the inclined surfaces in shaper. 

9. It is required to reduce the height of a workpiece of 200 mm. wide with 7 

mm. by a shaping machine. The stroke length is 450 mm. the shaper makes 

30 stroke/min with feed rate 0.6 mm/stroke and cutting angle 210º. Take the 

max. depth of cut equal 5 mm. Calculate: 

• Average cutting and return speeds. 

• The machining time. 

• How can the feed adjusted if the shaper table cross slide lead screw 

has 5 mm. pitch and tooth wheel of 75 teeth.

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