Hard Turning Versus Grinding

Hard turning is often considered a replacement for grinding operations or as a pre-grinding process.

Hard turning is often considered a replacement for grinding operations or as a pre-grinding process. It is most often performed on post-heat treated parts with surface hardness ranging from 45 HRC to 68 HRC or higher. Grinding, however, achieves higher tolerances than hard turning, but in cases where grinding can be replaced with hard turning, there are numerous benefits.

Hard turning’s benefits include shorter cycle times and part loading and unloading times as well as chip production that can be recycled and better energy efficiency. Turning centers cost less than precision grinders and provide a range of processes. They also require less tooling inventory. 

Although there is a small learning curve that goes along with hard turning, the fundamental principles follow those of the same turning operations that are commonly performed in shops today. This gives it an advantage over grinding, which requires specific knowledge and experience that not all machinists possess.

Since parts can typically be finished in a single chucking, hard turned parts often show superior concentricity and perpendicularity characteristics to their ground counterparts.
Read more about hard turning’s benefits by reading “Hard Turning as an Alternative to Grinding,” "Getting the Most Out of Hard Turning” and “Success Factors for Hard Turning.”
Combining Hard Turning and Grinding” is another interesting read.
 

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Getting the Most Out of Hard Turning

Traditionally, production of most parts made from hard or hardened materials, defined as those at or more than 45 HRc, required dedicated grinding equipment and processes.