MILLING AND TURNING OPERATIONS

JUTUR SAI KRISHNA

MILLING OPERATIONS

INTRODUCTION :

•Milling is the machining process of using rotary cutters to

remove material from a work piece advancing (or feeding) in a

direction at an angle with the axis of the tool.

•It covers a wide variety of different operations and machines, on

scales from small individual parts to large, heavy-duty gang

milling operations.

•It is one of the most commonly used processes in industry and

machine shops today for machining parts to precise sizes and

shapes.

PRINCIPLE OF MILLING MACHINE:

•Milling operates on the principle of rotary motion.

•A milling cutter is spun about an axis while a work piece is

advanced through it in such a way that the blades of the cutter are

able to shave chips of material with each pass.

•Axis of tool rotation is perpendicular to feed.

HORIZANTAL MILLING MACHINE :

•A horizontal mill has the same sort of x–y

table, but the cutters are mounted on a

horizontal arbor across the table.

•Many horizontal mills also feature a built-in

rotary table that allows milling at various

angles; this feature is called a universal table.

VERTICAL MILLING MACHINE :

•In the vertical mill the spindle axis is

vertically oriented.

•Milling cutters are held in the spindle and

rotate on its axis.

•There are two subcategories of vertical mills:

the bed mill and the turret mill.

OPERATIONS PERFORMED ON MILLING MACHINE :

Plain milling:

•Up milling and down

milling:- Machining is

done by the teeth on the

cylindrical surface of the

cutter, Finished surface is

parallel to the axis of the

cutter.

OPERATIONS PERFORMED ON MILLING MACHINE :

Face milling:•Machining is done by the teeth on the flatsurface of the cutter, Finished surface isperpendicular to the axis of the cutter.

Side and face milling:•Machining is done by the teeth on the flat aswell as cylindrical surface of the cutter, finishedsurfaces are perpendicular as well as parallel tothe axis of the cutter.

Side milling:•Machining is done by the teeth on thecylindrical surface the cutter, Finishedsurface is parallel to the axis of the cutter.

OPERATIONS PERFORMED ON MILLING MACHINE :

Profile milling:•The cutter has outline same as that of theshape of the profile. It is used for gear teethmanufacturing.

End milling:•The machining is done by the cutterteeth on the end as well as periphery ofthe cutter. It is used for machining ofcomplicated profiles.

Gang milling:•Two or more milling cutters aremounted on the arbor. Horizontal andvertical surfaces are machinedsimultaneously.

OPERATIONS PERFORMED ON MILLING MACHINE :

Saw milling( Slitting):

•The thickness of cutter issmall.(0.75 to 5 mm) It is usedfor cutting deep slots or forcutting off operations.

Keyway milling:

•Keyways can be prepared byusing side and face millingcutter on horizontal millingmachine or end milling cutteron vertical milling machine.

TURNING OPERATIONS

INTRODUCTION :

•This operation is one of the most basic machining processes.

That is, the part is rotated while a single point cutting tool is

moved parallel to the axis of rotation.

•Turning can be done on the external surface of the part as well as

internally (boring).

•The tool's axes of movement may be literally a straight line, or

they may be along some set of curves or angles, but they are

essentially linear.

•Performed on a machine tool called a lathe.

PRINCIPLE OF TURNING MACHINE:

•Turning is a form of machining, a material removal process, which

is used to create rotational parts by cutting away unwanted

material.

•The turning process requires a turning machine or lathe, work

piece, fixture, and cutting tool.

•Here the cutting tool remains constant and the work piece is in

rotating motion.

TURNING OPERATIONS:

FACING:

•Facing in the context of turning

work involves moving the cutting

tool at right angles to the axis of

rotation of the rotating work piece.

•Tool is fed radially inward.

•Profiling is also done in this.

PARTING:

•This process, also called parting

off or cut-off, is used to create deep

grooves which will remove a

completed one or part-complete

component from its parent stock.

TURNING OPERATIONS:

GROOVING:

•Grooving is like parting,

except that grooves are cut

to a specific depth instead

of severing a completed/

part-complete component

from the stock.

• Grooving can be

performed on internal and

external surfaces, as well as

on the face of the part (face

grooving or trepanning).

TURNING OPERATIONS:

BORING:•Enlarging or smoothing an existing hole created by

drilling, moulding etc. That is the machining of

internal cylindrical forms.

a) By mounting work piece to the spindle via a

chuck or faceplate.

b) By mounting work piece onto the cross slide and

placing cutting tool into the chuck. This work is

suitable for castings that are too awkward to mount

in the face plate.

KNURLING:

•The cutting of a serrated pattern

onto the surface of a part to use as a

hand grip using a special purpose

knurling tool.

TURNING OPERATIONS:

DRILLING:

•Drilling is used to remove

material from the inside of a work

piece.

•This process utilizes

standard drill bits held stationary

in the tail stock or tool turret of

the lathe.

REAMING: •The sizing operation that removes a

small amount of metal from a hole

already drilled.

•It is done for making internal holes of

very accurate diameters. For example,

a 6mm hole is made by drilling with

5.98 mm drill bit and then reamed to

accurate dimensions.

TURNING OPERATIONS:

THREADING:

•Both standard and non-standard screw

threads can be turned on a lathe using an

appropriate cutting tool.

• (Usually having a 60, or 55° nose

angle) Either externally, or within a

bore. Generally referred to as single-

point threading.

•Tapping of threaded nuts and holes

a) using hand taps and tailstock centre.

b)using a tapping device with a slipping

clutch to reduce risk of breakage of the

tap.

TURNING OPERATIONS:

TAPER TURNING:

•The taper turning is an operation

of producing a conical surface by

gradual reduction in the diameter

of a cylindrical work piece.

POLYGONAL TURNING:

•In which non-circular forms are

machined without interrupting the

rotation of the raw material.

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