Explain the Effect of Cutting Speed

Increase in cutting speed improves the surface finish due to the continuous reduction in built up edge. The curve a represents the machining of steels except high alloy grade steels. In the beginning the surface roughness increases when cutting speed changes from V₁ to V₂. This is due to the beginning of built up edge formation which reaches its maximum value at the cutting speed V₂. Then the formation of built up edge is reduced due to the rise in temperature and at cutting speed V₂ it almost disappears. This reduces the height (H) of micro irregularities. There is almost no hump on the curve B obtained in machining high alloy steels. Non-ferrous metal and cast iron, this is due to the completed absence of built up edge formation.