Turning and Related Operations
MACHINING OPERATIONS
Turning – a machining
process in which a singlepoint tool remove material
from the surface of a
rotating work piece. (Lathe)
Outline
• Turning and Related Operations
• Drilling and Related Operations
• Milling
• Machining & Turning Centers
• Other Machining Operations
v
Df
Do
d
f
L
v
N=
πDo
Rotational Speed
Do − D f = 2d
f r = Nf
– Shaping and Planing
– Broaching
– Sawing
Tm =
• Machinability
Feed rate
L
fr
Time of machining
MRR = vfd Material Removal Rate
Dr. M. Medraj
Mech 421/6511 lecture 20/1
Mech. Eng. Dept. - Concordia University
Mech. Eng. Dept. - Concordia University
Dr. M. Medraj
Operations Related to Turning
Contour turning
Facing
Taper turning
Work Holding
Chamfering
Form turning
three-jaw chuck
mounting the work between
centers using a "dog”
Cutoff
Threading
Boring
Drilling
Knurling
collet
Dr. M. Medraj
Mech 421/6511 lecture 20/2
Mech. Eng. Dept. - Concordia University
Mech 421/6511 lecture 20/3
Dr. M. Medraj
face plate for non-cylindrical workparts
Mech. Eng. Dept. - Concordia University
Mech 421/6511 lecture 20/4
Other Lathes & Turning Machine
Engine Lathe
• Toolroom Lathe and Speed Lathe
• Turret Lathe
– The tailstock is replaced with a
turret
• Chucking Machines – No tailstock
• Automatic Bar Machine – Similar to
chuck machine but with a collet
– A single- and multiple-spindle bar
machines
• NC Lathe
• Boring Machines – the stiffness of a
boring bar
– Horizontal and Vertical
Mech. Eng. Dept. - Concordia University
Dr. M. Medraj
Mech 421/6511 lecture 20/5
Drilling and Related Operations
Mech 421/6511 lecture 20/6
Mech. Eng. Dept. - Concordia University
Dr. M. Medraj
Operation Related to Drilling
• Geometry of Twist drill
– Shank, Neck and Drill body
– Helix angle, Point angle, Flute,
cutting edge, Chisel edge, Margin
• Cutting conditions
Spindle rpm:
Feed rate:
N=
v
πD
f r = Nf
f(in/rev)
Metal Removal Rate: MRR =
Machining time:
Dr. M. Medraj
Reaming
Tapping
Counterboring
πD f r
2
4
For a through hole
t+A
Tm =
fr
Mech. Eng. Dept. - Concordia University
For a blind hole
Tm =
d
fr
Mech 421/6511 lecture 20/7
– Countersinking
– Center drilling
– Spot facing
Dr. M. Medraj
Mech. Eng. Dept. - Concordia University
Mech 421/6511 lecture 20/8
Milling
Machine Tool for drilling
A machine operation in which a workpart is fed past a rotating cylindrical
tool with multiple edges. (milling machine)
• Drill press
–
–
–
–
–
Upright drill
Bench drill
Radial drill
Gang drill –2-6 drills together
NC drill
Types:
9 Peripheral milling
Up Milling
– Slab, slotting, side and straddle milling
– Up Milling (Conventional) & down milling (Climb)
9 Facing milling
• Vice, Jig and fixture
Upright drill press
– Conventional, Partial face, end, profile, pocket & contour
Down Milling
Radial drill press
Large drill press designed for large parts
(a) peripheral milling
Mech. Eng. Dept. - Concordia University
Dr. M. Medraj
Mech 421/6511 lecture 20/9
(b) face milling
Mech. Eng. Dept. - Concordia University
Dr. M. Medraj
Milling
Mech 421/6511 lecture 20/10
Cutting Conditions
• Milling cutters
Slab
slotting
side
straddle
–
–
–
–
Plain milling cutters
Form milling cutters
Face milling cutters
End milling cutters
Radial Rake
Angle
Relief
Angle
• Cutting conditions
conventional
face milling
Partial face
milling
end milling
Spindle rotation speed: N =
profile milling
pocket milling
Dr. M. Medraj
Surface contouring
Mech. Eng. Dept. - Concordia University
Feed rate:
v
πD
f r = Nnt f
MRR: MRR = wdf r
Mech 421/6511 lecture 20/11
Dr. M. Medraj
Mech. Eng. Dept. - Concordia University
Mech 421/6511 lecture 20/12
Milling Machines
Machining Centers
• Machining center – highly automated machine tool capable of
performing multiple machining operations under CNC control.
– Automatic tool changer
– Pallet shuttles
– Automatic workpart positioning
horizontal knee-and-column
vertical knee-and-column
ram type knee-and-column milling
machine; ram can be adjusted in and
out, and toolhead can be swiveled
Mech. Eng. Dept. - Concordia University
Dr. M. Medraj
Mech 421/6511 lecture 20/13
•
•
Dr. M. Medraj
Mech. Eng. Dept. - Concordia University
Mech 421/6511 lecture 20/14
Other Machining Operations: Shaping and Planing
Mill-Turn Centers
•
CNC turning center
Highly automated machine tool that can perform turning, milling, and
drilling operations on a workpart
General configuration of a turning center
Can position a cylindrical workpart at a specified angle so a rotating
cutting tool (e.g., milling cutter) can machine features into outside
surface of part
• A single-point tool moves linearly relative to the work part
– A conventional turning center cannot stop workpart at a defined angular
position and does not possess rotating tool spindles
Shaping - A tool moves
Planing – A workpart moves
A part
Stock
Dr. M. Medraj
Turning
Milling
Mech. Eng. Dept. - Concordia University
Drilling
Mech 421/6511 lecture 20/15
Dr. M. Medraj
Mech. Eng. Dept. - Concordia University
Mech 421/6511 lecture 20/16
Other Machining Operations: Broaching
Other Machining Operations: Sawing
• Moves a multiple tooth cutting tool linearly relative to work in
direction of tool axis
Advantages:
- Good surface finish
- Close tolerances
- Variety of work shapes possible
• Cutting tool called a broach
- Owing to complicated and often custom-shaped geometry, tooling
is expensive
power hacksaw –linear reciprocating motion of
hacksaw blade against work
Internal Broaching:
•
•
Performed on internal surface of a hole
A starting hole must be present in the part to insert broach at beginning
of stroke
bandsaw (vertical) – linear
continuous motion of bandsaw blade
circular saw
Dr. M. Medraj
Mech. Eng. Dept. - Concordia University
Mech 421/6511 lecture 20/17
Dr. M. Medraj
Mech. Eng. Dept. - Concordia University
Mech 421/6511 lecture 20/18
Machinability
• Machinability – A measure of the success of a machining
operation usually on a workmaterial.
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–
–
–
–
Dr. M. Medraj
Tool life
Force and Power
Surface finish
Easy of chip disposal
Material Removal rate
Mech. Eng. Dept. - Concordia University
Next Time:
Cutting Tool Technology
Mech 421/6511 lecture 20/19
Dr. M. Medraj
Mech. Eng. Dept. - Concordia University
Mech 421/6511 lecture 20/20