First Year,

Mechanical Engineering Dept.,

Faculty of Engineering,

Fayoum University

Dr. Ahmed Salah Abou Taleb

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Manufacturing Processes 1(MDP 114)

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Machining Operations & Machine Tools

Machine

Turning

Milling

Drilling

Shaper

BroacherSaw

Screw Thread

Gears

Planner

Milling Machine

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Definition

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Machining operation in which work is fed past a rotating tool with multiple cutting edges.

• Axis of tool rotation is perpendicular to feed direction.

• Creates a planar surface; other geometries possible either by cutter path or shape.

• Other factors and terms:

• Milling is an interrupted cutting operation.

• Cutting tool called a milling cutter, cutting edges called teeth.

• Machine tool called a milling machine.

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Milling Machine

Milling Machine

Horizontal Vertical Ram

Milling Machine

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(a) horizontal milling machine

Milling Machine

7(b) vertical milling machine

Milling Machine

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(b) ram type machine; ram can

be adjusted in and out, and tool head can be swiveled

Forms of Milling

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Two forms of milling:

(a) peripheral milling, and (b) face milling

Peripheral Milling vs. Face Milling

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Peripheral milling:

Cutter axis is parallel to surface being machined.

Cutting edges on outside periphery of cutter.

Face milling:

Cutter axis is perpendicular to surface being milled.

Cutting edges on both the end and outside

periphery of the cutter.

Milling Operations

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Slab Milling:

The basic form of peripheral milling in which the cutter width extends beyond the workpiece on both sides

Milling Operations

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Conventional Face Milling:

Cutter overhangs work on both sides

Milling Operations

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Slotting:

Width of cutter is less than workpiece width, creating a slot in the work

Milling Operations

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End Milling :

Cutter diameter is less than work width, so a slot is cut into part

Milling Operations

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Profile Milling :

Form of end milling in which the outside periphery of a flat part is cut

Milling Operations

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Pocket Milling:

Another form of end milling used to mill shallow pockets into flat parts

Milling Operations

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Surface Contouring :

Ball-nose cutter is fed back and forth across the work along a curvilinear path at close intervals to create a three dimensional surface form

Milling Operations

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Drilling:

Creates a round hole in a workpart. Cutting tool is called a drill or drill bit. Customarily performed on a drill press, but can be done on avertical mill and on a lathe.

Milling Operations

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Reaming:

Used to slightly enlarge a hole, provide better tolerance on diameter, and improve surface finish.

Milling Operations

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Tapping:

Used to provide internal screw threads on an existing hole.

The tool is called a tap

Milling Operations

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Counterboring:

Provides a stepped hole, in which a larger diameter follows a smaller diameter partially into the hole

Cutters for Different Types of Milling

22Cutters for (a) Straddle Milling, (b) form milling, (c) slotting, and (d) slitting with a

milling cutter.

Cutters for Different Types of Milling

23(a) T-slot cutting with a milling cutter. (b) A shell mill.

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Milling Cutting Tools

Machining Calculations

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r

mf

DLT

• Cutting (Spindle) Speed: rpm

v = cutting speed, D = cutter diameter

• Feed Rate: (mm/min)f = feed per tooth , nt = number of teeth

• Material Removal Rate (mm3/min)w = width, d = depth of cut

D

vN

fnNf tr

rfdwMRR

Machining Calculations

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r

mf

DLT

• Machining Time:

– Slab Milling: (min)

L = length of cut, d = depth of cut

– Face Milling:

• For single pass:

• For multi-passes:

w = width of cut

Dπ

vN

r

mf

dDdLT

r

mf

DLT

5.0

r

mf

wDwLT