Rough hard turning of rolls application example 04:10

In hard turning applications, the definitions for a rough cut and a finish cut are based on depth of cut:

• Rough cut depth of cut ap > 0.5 mm
• Finish cut depth of cut ap < 0.5 mm 

For rough hard turning, usually a high cBN-content grade (80-90% cBN) is used, and for finishing, a low cBN-content grade (40-65% cBN) is used.

Most components in the automotive industry, like gears and shafts, are case hardened and only require a finish cut before assembly. In the bearing industry as well as in the manufacturing of rolls, rough hard turning is a more common operation.

The main requirements on a CBN-grade for rough hard turning are:

• high abrasion resistance
• high hot hardness

But they also need to be tough enough to withstand e.g. variations in depth of cut.

A customer was using ceramics for hard turning of a roll. He was taking 10 cuts, each 0.15 mm depth of cut, to remove the total stock of 1.5 mm. To finish the component, he needed 40 edges.

Ceramics are not suited for these kinds of operations due to their lack of toughness. By using rough hard turning with a CBN-insert, tool life was increased significantly and thereby reducing machine downtime due to insert change. With this method, he only needed 2 edges to finish the component.

By using rough hard turning, productivity can be increased significantly compared to e.g. grinding or the use of multiple finishing cuts

For more information, please contact your local Seco representative, or our Advanced material (PCBN/PCD/CERAMIC) team.

Author: Henrik Sandqvist Product Specialist SECOMAX PCBN/PCD/CERAMIC SECO TOOLS Shanghai CO., Ltd. Level 2, Building 8, 456 HongCao Rd., Shanghai 200233, China Office: +86 21 5426 5849 Mobile: +86 185 1520 6942 e-mail: henrik.sandqvist@secotools.com

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