Discontinuous chips in metal cutting are commonly formed due to which of the following reasons? 

Explanation:

Machining of metals and formation of chips

Types of chip:

1. Discontinuous chips – Formed during machining of brittle materials and while machining ductile materials at low speed.

Favourable conditions for this are:

1. Brittle workpiece
2. Slow speed of cutting
3. Small rake angle
4. Large depth of cut

As ceramic materials are brittle in nature hence discontinuous chips are formed.

2. Continuous chips – formed during machining of ductile materials at high speed. Favourable conditions for this type of chip to be formed are as follows:

• Ductile material
• Large rake angle
• High cutting speed
• Low depth of cut
• Proper use of coolant and lubricant

Benefits of continuous chips are:

• Gives high surface finish
• High tool life
• Low power consumption

3. Continuous chips with builtup edges – These type of chips are formed during the machining of ductile materials at medium cutting speed. Favourable conditions for this are:

• Ductile material
• High friction at the face of the tool
• Lack of coolant and lubricant