Types of Chips

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Types of chips:


Following are the three common types of chip from a single point tool:

 1. Continuous Chips:


Continuous chips are formed by the continual plastic deformation of metal without fracture ahead of the leading edge of the tool and is made by the graceful flow of the chip up the tool face. MS steel and copper are considered to be most desirable materials for obtaining continuous chips. The chips obtained have same thickness throughout. This type of chip is the most desirable. Since its stable cutting, leading to generally good surface finish. On the opposite hand these chips are difficult to handle and dispose off.
Continuous chips tend to be formed when the subsequent condition exist:
• Ductile material
• High cutting speed
• Small chip thickness
• Large rack angle

2. Discontinuous or Segmental chip:




This type of chips are made by a series of rupture occurring approximately perpendicular to the tool place face each chip element passing off along the tool face the chip element in the form of small segment may adhere loosely to every other and becomes slightly longer.
Since the chips hack into small segments the friction between the tool and thus the chips reduces’ resulting in better surface finishing. These chips are convenient to collect handle and dispose off. Discontinuous chips tend to be formed when one or more or the subsequent conditions exist:

• Brittle material, such as cast iron and bronze.
• Large chip thickness
• Low cutting speed
• Small rack angle

Discontinuous chips also are produced when cutting more ductile material with the utilization of a cutting fluid.




3. Continuous Chip with Built up Edge:



This type of chip is extremely almost like the continual chip. With the difference that it's a built up edge adjacent to tool face and also it's not so smooth. It is obtained by machining on ductile material, during this condition of high local temperature and extreme pressure within the cutting and high friction within the tool chip interference, may cause the work material to stick or weld to the leading edge of the tool. Successive layers of labor material are then added to the built up edge. When this edge becomes larger and unstable, it breaks up and a part of it's carried up the face of the tool along side the chip while the remaining is left over the surface being machined, which contributes to the roughness of the surface. The built up edge changes its size during the cutting operation. It first increases, then decreases, and then again increases etc.




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