Method of Feeding on Milling Machine

There are two distinct method of feeding the work when operating a cutter on milling machine.

Conventional milling

When the work is fed in a direction that is opposite to the rotation of the milling cutter which is also known as up cut milling. The up cut milling is very generally used.
Up Cut Milling
Up Cut Milling

Climb Milling

When the work is fed in a direction that is same as the direction of rotation of cutter, which is also known as down cut milling. The down cut milling is less commonly used. Though the down cut milling has certain advantages over conventional milling, down cut milling  impose  certain  restrictions.  Down cut milling cannot be used on all machines except on those machines that are design to take up the backlashes between the lead screw and its nut. Further the teeth of milling cutter come into contact with, and begun to cut into, a heavy section of metal instead of a zero edged section as in conventional milling.
Down Cut Milling
Down Cut Milling
Advantages of Climb Milling
(a) Increased Tool Life - Since the chips pile up behind or to the left of the cutter, tool life can be increased.

(b) Less Costly Fixtures Required - Climb milling forces the work piece down instead of trying to lift as with conventional milling; therefore, simpler holding devices are required.

(c) Improved Surface Finish - Chips are less likely to be carried into the work piece by the cutter teeth, which prevent damage to the work surface.

(d) Less Edge Breakout - Because the thickness of the chip tends to get smaller as it nears the edge of a workspace, there is less chance of breaking, especially with brittle materials.

(e) Lower power requirements - Since a cutter with a higher rake angle can be used, approximately 20 percent less power is required to remove the same amount of metal.

Disadvantages of Climb Milling

This method cannot be used unless the machine has a backlash eliminator and the table gib have been tightened. . It cannot be used for machining castings or hot-rolled steel since the hard outer scale will damage the cutter.

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