The addition of lead, sulphur and phosphorus to low carbon steels, help to
* reduce built up edge
* break up chips
* improve machinability

Discontinuous chips Discontinuous chips are usually formed during machining of brittle materials like cast iron. The low cutting speed and small rake angle of the tool are responsible for the formation of discontinuous chips.

Continuous chips Continuous chips are produced during machining of ductile materials like mild steel. The high cutting speed and large rake angle of the tool will result in the formation of continuous chips. These chips are in the form of long coils having the same thickness throughout.

Continuous chips with built up edge Continuous chips with built up edge are also produced during machining of ductile materials. The low cutting speed and small rake angle of the tool will result in the formation of continuous chips with built up edge. These chips are also formed when the cutting edge of the tool is dull.

Discontinuous chips Discontinuous chips are usually formed during machining of brittle materials like cast iron. The low cutting speed and small rake angle of the tool are responsible for the formation of discontinuous chips.

Continuous chips Continuous chips are produced during machining of ductile materials like mild steel. The high cutting speed and large rake angle of the tool will result in the formation of continuous chips. These chips are in the form of long coils having the same thickness throughout.

Continuous chips with built up edge Continuous chips with built up edge are also produced during machining of ductile materials. The low cutting speed and small rake angle of the tool will result in the formation of continuous chips with built up edge. These chips are also formed when the cutting edge of the tool is dull.