Material Removal Process

swing

The maximum diameter of the workpiece that can be machined

Sharper

(like a printer) cutting tool has primary motion

Machining Processes

turning, drilling, milling, shaping, planing, broaching, sawing

cutting conditions

-Cutting speed (v): primary/speed motion -Feed (f): secondary/feed motion -Depth of cut (d): penetration of the tool below original work surface

Peripheral milling

-The axis of tool is parallel to the surface being machined. -Only involve cutting edges on the outside periphery of the cutter

Face Milling

-The axis of tool is perpendicular to the surface being machined. -Involve cutting edges on both the end and outside periphery of the cutter

Types of Cutting Tools

1. single-point tools 2. multiple cutting edge tools

Turning

A single point cutting tool removes material from a rotating workpiece to generate a cylindrical shape -Performed on a machine tool called a lathe

Turning Cutting Conditions

Cutting Speed (v), Feed (f), Depth of cut (d)

Pocket milling

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

cutting fluids

Any liquid that is applied directly to the machining operation to improve cutting performance -Reduce friction and wear -Cool the cutting zone -Wash away the chips

Finishing

Complete the part and achieve the final specifications Low feeds (0.005-0.015 in./rev) and depths (0.03-0.075 in) , high cutting speeds

End milling

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

Conventional face milling

Cutter overhangs work on both sides

Nontraditional Processes

Electrical, chemical, thermal and hydrodynamic methods to remove material -Water jet cutting, EDM, LBM

Abrasive Processes

Hard and abrasive particles + mechanically remove material -Grinding, honing, and lapping

Main parts of Lathe

Headstock, carriage, tailstock

Fundamental Inputs

Machine tools workholding devices cutting tools workpiece parameters cutting conditions

broach

Moves a multiple tooth cutting tool linearly relative to work in direction of tool axis

End/side cutting edge angle

SCEA determine the entry of the tool into the work; ECEA provides a clearance

Cutoff/parting

To cut off the end of the part. The tool is fed radially into the part at some location

Facing

To produce a flat surface at the end of the part. The tool is fed radially into the rotating workpiece on one end.

Taper turning

To produce a tapered cylinder or conical shape. The tool is fed at an angle

Straight Turning

To reduce the diameter. The tool is fed parallel to the axis of rotation of the workpiece

End/side relief angle

determine the amount of the clearance between the tool and the freshly cut work surface

Back/side rake angle

determine the direction of chip flow

Nose radius

determine the texture of the surface generated

Flank wear

formed by the rubbing between machined surface and the flank face adjacent to the cutting edge

Crater wear

formed by the sliding of chip against the surface

Tool wear

gradual wearing of the cutting edge

Knurling

is to produce a regular cross- hatched pattern in the part surface.

Boring

like the straight turning, but performed on the inside of an existing hole in the part to enlarge a hole.

Counterboring

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

Roughing Cuts

remove large amount of material as rapidly as possible High feeds (0.015-0.05 in./rev) and depths (0.1 -0.75 in), low speeds

Helix angle

the angle of the spiral flutes

Slab milling

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

Depth of cut (d)

the difference between the original surface and machined surface. (mm, in.)

Feed (f)

the distance the tool travels during one revolution of the workpiece. (mm/rev, in./rev)

Flute

the spiral grooves; acts as passageways for chips and cutting fluid

Cutting Speed (v)

the tangential speed of the workpiece (m/s, ft/min)

web

the thickness between the flutes

Contour turning

the tool follows a contour to create a contoured form in the part.

Form turning

the tool has a shape that is imparted to the part

Tapping

to provide internal threads on an existing hole. Tool called a tap

Reaming

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

Slotting

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

Planer

workpiece has primary motion