Operations i\of machine tools

7/31/2019 Operations i\of machine tools

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MACHINING OPERATIONS

AND MACHINE TOOLS1. Turning and Related Operations

2. Drilling and Related Operations

3. Milling4. Machining & Turning Centers

5. Other Machining Operations

6. Shape, Tolerance and Surface Finish7. Machinability

8. Selection of Cutting Conditions

9. Product Design Consideration


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d

f

Do Df

L

1. Turning & Related Operations

Turning a machiningprocess in which a

single-point tool removematerial from thesurface of a rotatingwork piece. (Lathe)

v vfdMRR

f

LT

Nff

dDD

D

vN

r

m

r

fo

o

=

=

=

=

=

2

Rotational Speed:

Feed rate:

Time of machining:

Material Removal Rate:


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Operations related to Turning

Facing Taper turning

Contour turning

Form turning

Chamfering

Cutoff Threading Boring Drilling

Knurling


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Work Holding

Mounting betweentwo centers (Dog &

Live center)

Chuck

Collet

Face plate


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Engine Lathe

BedCarriage

HeadstockTailstock

Toolpost

ThreadedLead Screw


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Other Lathes & Turning Machine

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 colletA single- and multiple-spindle bar machines

NC Lathe


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Boring Machining

Horizontal Boring Machining Vertical Boring Machining

Boring Cutting is done inside diameter of the work

material


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2. Drilling & Related Operations Geometry of Twist drill

Shank, Neck and Drill body

Helix angle, Point angle, Flute, cuttingedge, Chisel edge, Margin

Cutting conditionsD

vN

=Spindle: Feed rate: Nffr =

Metal Removal Rate:4

2

rfDMRR

=

Machining time:r

mf

AtT

+= For a through hole

For a blind holer

m

f

dT =

A

t d

f(in/rev)


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Twist Drill and Drilling Operations

From Kalpakjian and Schmid (2003)


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Machine Tool for drilling

Drill pressUpright drill

Bench drill

Radial drill

Gang drill - 2-6 drills together

NC drill

Vice, Jig and fixture


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3. Milling

Milling A machine operation in which a

work part is fed past a rotatingcylindrical tool with multipleedges. (milling machine)

Types

Peripheral milling Slab, slotting, side and

straddle milling

Up Milling (Conventional) &

down milling (Climb)Facing milling

Conventional face, Partialface, End, Profile, Pocket &

contour millings

Up Milling Down Milling

Slab

slotting

side

straddle Face Milling

Conventional face

Partial face

End

Pocket

Peripheral Milling

Contour

Profile


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Cutting conditions

Milling cutters

Plain milling cuttersForm milling cutters

Face milling cuttersEnd milling cutters

Cutting conditionsSpindle rotation speed: D

vN

=

Feed rate: fNnf tr =

Material Removal Rate:rwdfMRR =

ReliefAngle

ClearanceAngle

Radial RakeAngle


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Milling Machines

Knee-and-column MillingMachine

Horizontal and Vertical types Universal and Ram types

Bed-type Mill

Planer-type Mills the largest

category Tracer (profile) Mill

reproduce an irregular partgeometry

CNC Milling machine

Horizontal Vertical

Universal Ram

Bed-type mill


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Machining Centers

Machining center highly automated

machine tool capable of performingmultiple machining operations under CNCcontrol.

Automatic tool changerPallet shuttles

Automatic workpart positioning

CNC turning center


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A CNC mill-turn center

A part

Stock Turning Milling Drilling

A series of operations without human interactions

From a round stock

From a casting

From another casting


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5. Other Machining Operations

Shaping and planing

A single-point tool moves linearly relative to the work part

Shaping - A tool moves Planing A workpart moves

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


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Broaching

Finishing teeth

Semifinishingteeth

Roughing teeth


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Sawing

Saw Blade (Straight & Undercut toothor Straight & Raker sets)

Bandsaw - linear continuous motion

Hacksaw - linear reciprocating motion

Operations i\of machine tools

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