Up Milling and Down Milling Operation - Advantages, Application
Read: Elements of Plain Milling Cutter - Nomenclature and Angles
There commonly two type of milling operation with cylindrical cutters
Conventional MillingIn a conventional milling operation, the cutter rotates against the direction in which work feeding. The chip thickness varies zero at tooth entrance and maximum at tooth exit. This gradual increase in thrust has advantages for the sharp-edged tooth. This type of milling, the cutter has the tendency to pull away the workpiece, so it is also called up milling. The cutting at starting very light so that teeth slide across the surface. The sliding and biting behavior cause poor surface finish. The chips formed during cutting disposed ahead of the cutter. It has no tendency to drag workpiece into the cutter, so it is a safe operation. The selection type of milling operation mainly depends upon the nature of work. These type of milling generally used for milling of casting and forging.
Climb millingIn this type of milling the cutter rotate the same direction as that in which the work is feeding. The cutting-edge subjected to high load at the beginning of cutting. It is not recommended for older machines. This type of loading is suitable for carbide milling cutter. In climb milling, the cutter has the tendency to push workpiece towards the table, so it is also called down milling. Tendency of holding down the workpiece reduces the cutting vibration. It has tendency to drag workpiece into cutter, so there is a safety issue.
The chip during the cutting process leaves behind the cutter, which eases the chip removal. It possess longer tool life. This type of milling generally used for finishing operation. It produces a good surface finish. Application are: sawing, grooving, slotting, keyway cutting etc.