1. Turning & Related Operations
MACHINING OPERATIONS
AND MACHINE TOOLS
• Turning – a machining
v
Rotational Speed: N =
process in which a
πDo
single-point tool remove
Do − D f = 2d
material from the
f r = Nf
Feed
rate:
surface of a rotating
L
work piece. (Lathe)
Time of machining: Tm =
1. Turning and Related Operations
2. Drilling and Related Operations
3. Milling
4. Machining & Turning Centers
5. Other Machining Operations
6. Shape, Tolerance and Surface Finish
7. Machinability
8. Selection of Cutting Conditions
9. Product Design Consideration
Material Removal Rate:
Do
v
Df
d
1
L
f
Operations related to Turning
Contour turning
Facing
Taper turning
fr
MRR = vfd
2
Work Holding
Chamfering
• Mounting between
two centers (Dog &
Live center)
• Chuck
Form turning
• Collet
• Face plate
Cutoff
Threading
Boring
Drilling
Knurling
3
Engine Lathe
Headstock
4
Other Lathes & Turning Machine
Tailstock
• Toolroom Lathe and Speed Lathe
• Turret Lathe
Tool
post
– The tailstock is replaced with a turret
Carriage
• Chucking Machines – No tailstock
• Automatic Bar Machine – Similar to chuck
machine but with a collet
Bed
– A single- and multiple-spindle bar machines
Threaded
Lead Screw
• NC Lathe
5
6
1
Boring Machining
2. Drilling & Related Operations
• Geometry of Twist drill
• Boring – Cutting is done inside diameter of the work
material
– Shank, Neck and Drill body
– Helix angle, Point angle, Flute, cutting
edge, Chisel edge, Margin
• Cutting conditions
Spindle: N =
Horizontal Boring Machining
Vertical Boring Machining
v
πD
Feed rate: f r = Nf
f(in/rev)
πD 2 f r
Metal Removal Rate: MRR =
t+A 4
Machining time: Tm =
f r For a through hole
A
d
Tm =
For a blind hole
d
t
fr
7
8
Machine Tool for drilling
Twist Drill and Drilling Operations
• Drill press
– Upright drill
– Bench drill
– Radial drill
– Gang drill - 2-6 drills together
– NC drill
• Vice, Jig and fixture
From Kalpakjian and Schmid (2003)
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3. Milling
• Milling
10
Cutting conditions
Up Milling
– A machine operation in which a
work part is fed past a rotating
cylindrical tool with multiple
edges. (milling machine)
• Types
Down Milling
Partial face
Slab
– Peripheral milling
• Slab, slotting, side and
straddle milling
• Up Milling (Conventional) &
down milling (Climb)
– Facing milling
• Conventional face, Partial
face, End, Profile, Pocket &
contour millings
Conventional face
End
slotting
Profile
• Milling cutters
– Plain milling cutters
– Form milling cutters
– Face milling cutters
– End milling cutters
• Cutting conditions
side
Contour
Pocket
straddle
Peripheral Milling
Face Milling
11
Spindle rotation speed:
Radial Rake
Angle
N=
v
Relief
Angle
Clearance
Angle
πD
Feed rate: f r = Nnt f
Material Removal Rate: MRR = wdf r
12
2
Milling Machines
Machining Centers
• Knee-and-column Milling Machine (Fig. 22.22
and Fig. 22.23)
– Horizontal and vertical types
– Universal and Ram types
• Bed-type Mill (Fig. 22.24)
• Planer-type Mills – the largest category
• Tracer (profile) Mill – reproduce an irregular part
geometry
• CNC Milling machine
• Machining center – highly automated
machine tool capable of performing
multiple machining operations under CNC
control.
– Automatic tool changer
– Pallet shuttles
– Automatic workpart positioning
• CNC turning center
13
A CNC mill-turn center
5. Other Machining Operations
A series of operations without human interactions
Stock
Turning
Milling
14
• Shaping and planing
– A single-point tool moves linearly relative to the work part
– Shaping - A tool moves
– Planing – A workpart moves
Drilling
A part
• Broaching
– Performed by a multiple-tooth cutting tool by moving linearly
relative to the work in the direction of the tool axis.
• Sawing
– Hacksawing, Bandsawing, and Circular sawing
From a casting
From a round stock
From another casting
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16
Broaching & Sawing
Hacksaw - linear reciprocating motion
Bandsaw - linear continuous motion
17
3