The sources of heat generation during metal cutting

The sources of heat generation during metal cutting

The sources of heat generation during metal cutting are the following.

1 Friction: 

A lot of friction always takes place between the cutting tool and the work piece and between the tool face and the chips passing over it. The total amount of heat generated depends upon many factors viz. cutting speed, feed, tool material, depth of cut and metal being machined. The heat so generated is known as heat of friction.

2. Plastic deformation of metal: 

Cutting tool exerts high pressure on the adjacent metal grains which due to this pressure start slipping along their planes of weakness. This causes deformation of all of them. The action of slipping of these grains in contact with one another causes friction, leading to the generation of the heat of deformation. The total amount of heat generated again depends upon the cutting speed, feed, depth of cut and the metal being machined. Higher speeds, feeds, more depth of cut, tougher materials contribute to greater heat generation.

3. Chip distortion: 

In machining, as the cut proceeds and the chips curl out, the inside and the outside grain of the chip metal are subjected to compression and tension respectively. This causes distortion of the chip grains are the chips leading to a sort of internal friction amongst the grains and consequently generation of heat of chip distortion. The amount of heat generated depends on feeds and depth of cut. Heavier the feed and deeper the cut, the longer will be the area of cross-section of the chip and more distortion amongst the grains, resulting in higher amount of heat generation.

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