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