Operations performed in milling machine-1

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Operations performed in milling machine 
Down milling (Climb milling) 
 
It is the operation of removing material by a cutter which is rotated in the same direction of 
travel of the workpiece. 
The thickness of the chip is maximum when the tooth begins its cut and it reduces to a 
minimum when the cut terminates. 
The cutter tooth starts removing metal immediately on reaching the work surface without 
sliding. 
The cutting force in down milling is also variable throughout the cut. It is maximum when 
the tooth begins its cut and it reduces to the minimum when the tooth leaves the work. 
The fixture design becomes easier as the direction of the cutting force is such that it tends to 
seat the work firmly in the work holding device. 
The chips are also disposed off easily and do not interfere with the cutting. 
The coolant can be poured directly at the cutting zone where the cutting force is maximum. 
This will result in improved surface finish and diminishes the heat generated. 
The down milling should only be performed on rigid machines without backlash error that 
may be present between the feed screw of the table and the nut. 
 
 
Face milling 
 
It is the operation performed by a milling cutter to produce a flat machined surface 
perpendicular to the axis of rotation of the (face milling) cutter. 
The peripheral cutting edges of the cutter do the actual work whereas the face cutting edges 
finish up the work surface by removing a very small amount of material. 
The depth of cut is adjusted by rotating the cross feed screw of the table. 
 
 
 
 
Side milling 
 
It is the operation of production of flat vertical surface on the sides of workpiece with the 
help of side milling cutter. 
The depth of cut is adjusted by rotating the vertical feed screw of the table. 
 
Straddle milling 
It is the operation of production of production of flat vertical surface on both sides of 
workpiece with the help of 2 side milling cutters mounted on the same arbor. 
The distance between the 2 cutters is adjusted by using suitable spacing collars. 
 
Angular milling 
 
 It is the operation of production of angular surface on a workpiece other than at right angles 
to the axis of the machine spindle. 
The angular groove may be single or double angle and maybe of varying included angle 
according to the type and shape of angular cutter used. 
 
Gang milling 
 
It is the operation of machining several surfaces of a workpiece simultaneously by feeding 
the table against a number of cutters having same or different diameters mounted on the 
arbor of the machine. This operation saves much of machining time. 
The cutting speed of the gang of cutter is calculated from the cutter having the largest 
diameter. 
 
Saw milling 
 
It is the operation of production of narrow slots or grooves in a workpiece by using a saw 
milling cutter. 
The saw milling operation can also be performed for complete parting-off operation. 
 
T-slot milling 
 
First milling a plain(open) slot can be cut on the workpiece by a plain milling cutter/metal 
slitting saw/end mill/side milling cutter. 
The shank of the T-slot milling cutter is introduce in to the first slot and the second (closed) 
slot is cut at right angles to the first slot. 
Also, a dovetail slot is made by special type of cutters designed. 
 
End milling 
 
It is the operation of production of flat surface which may be horizontal, vertical or at angle 
in reference to the table surface. 
This operation is used for production of slots, grooves or keyways on the workpiece. 
The end milling cutter performs the combination of peripheral & face milling operations as 
the cutter has teeth both on the end face and on the periphery. 
 
Form milling 
 
It is the operation of production of irregular contours on a workpiece by using form cutters. 
The contours can be concave, convex or any other shape. 
The cutting speed for form milling is 20% to 30% less than that of plain milling operation. 
 
Keyway milling 
 
It is the operation of production of keyways, grooves or slots of varying shapes and sizes by 
using a plain milling cutter, a metal slitting saw, an end mill or by a side milling cutter. 
 
Gear cutting 
The gear cutting operation is performed in a milling machine by using a form relieved cutter. 
The cutter may be cylindrical or end mill type. 
The cutter profile corresponds exactly with the tooth space of the gear. 
The work is mounted on a universal dividing head by indexing it to produce equally spaced 
gear teeth on the workpiece.