Face milling of case hardened steel with PCBN 02:55

Turning is the most common operation on case hardened steel components after heat treatment. The material “moves” during the case hardening process, and that is the reason why a finishing process is needed, to generate the required surface and dimensional tolerances. Typical components include gears and shafts etc for the automotive industry.

Still, there are applications also for finish milling of case hardened components. It could be a sealing surface where there are requirements on surface finish, but also on flatness.

Seco has been working with PCBN milling for many years, and have today both the experience and products to reach the customers’ goals. A typical example is a pump body, which has a sealing surface with requirements on both flatness and surface finish:

Currently grinding is used to finish the component, and the machining time per component is 8 minutes. The question is, can this be done with CBN?

The component was clamped in a 3-jaw chuck in the larger end, and supported by a tailstock at the smaller end in a machining center.

An adjustable square shoulder milling cutter, 63 mm in diameter, with four positive full-faced TPGW11 CBN-inserts (3 cutting edges per insert) was selected:

• Cutter R220.68-0063-TP11C-4, z=4 
• Insert TPGW1103PNS-LF, CBN200 

and the following conditions were used:

• Cutting speed 250 m/min 
• Feed rate 0.07 mm/tooth (350 mm/min) 
• Depth of cut 0.1 mm 

After machining of the first component, measuring was done, and it was well within the required tolerances. It was decided to continue and evaluate tool life, and it was possible to machine 106 components, equal to about 70 minutes time-in-cut.

So, what was the machining time when using CBN? For each component, the machining time was reduced from 8 minutes to 36 seconds. This is a large improvement, especially when you are making 1 400 components per day!

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. Building 4, No 797, Puxing Road, Pujiang Town, Minhang District, Shanghai 201114, China Office: +86 21 6091 2832 Mobile: +86 185 1520 6942 e-mail: henrik.sandqvist@secotools.com