Machining recommendation for Ductile Iron

Machinability is a multi-facetted concept encompassing not only productivity factors like speeds and feeds but also tool wear, surface finish, chip characteristics and power requirements.

It is an important attribute for an engineering material since machining can account for up to 50% of the overall manufacturing cost for a component. Thanks to the presence of graphite, ductile iron has excellent machinability, fully on-a-par with many free-machining steels. Graphite facilitates chip formation and at the same time lowers friction leading to reduced cutting forces and better tool life.

A rough indication of the effect of type of machining operation can be gained from the table below which illustrates the typical range of feasible machining speeds for turning, milling, etc.

In many instances, the combination of lower weight and better machinability than steel will more than compensate for a somewhat higher material price for ductile iron. This is illustrated by the following examples.