Cermet Inserts and Forming Tools for Bearing Ring Turning

Bearing ring machining is a high-volume, high-consistency finishing operation, which is exactly the regime where cermet pays. Koves supplies both standard bearing inserts and forming inserts and blanks, and the catalogue documents the productivity effect of turning the raceway form directly rather than leaving it to be ground.

The bearing machining range

The bearing section of the catalogue covers three groups. SNMN and TNMN ground inserts are used for ring turning; RPMT inserts, described as bearing turning inserts, cover grooving and profiling work; and F-JY forming insert blanks are supplied for custom forming tools where the customer grinds the profile they need.

The forming inserts are made in square and triangular shapes with processing diagrams for different ring features, which allows a single insert to generate a raceway, a shoulder or a groove profile in one pass.

Why cermet suits bearing rings

Bearing races demand dimensional consistency and a fine surface, and they are produced in large numbers from consistent steel. Both conditions favour cermet: it holds its size well because the edge is sharp and wears slowly, and it produces a finish that is close to the final requirement.

The alternative - rough turning, heat treatment, then grinding to final form - adds a process step and consumes material as grinding stock. Turning the form closer to final size reduces both.

The documented productivity effect

The catalogue reports that using its bearing forming inserts raises turning productivity by about 20% compared with the conventional route.

Because the turned form is closer to final size, the grinding allowance is reduced and the grinding stroke is shortened, which raises productivity in the grinding operation by an average of about 10%. The gain comes from both operations rather than from eliminating grinding entirely.

Standard inserts or forming tools

For rings where the profile is generated by a standard turning pass, SNMN and TNMN ground inserts cover the operation. For rings with a raceway or groove profile, an RPMT round insert or a custom F-JY forming tool produces the form in one plunge.

Forming tools require the profile to be ground into the blank. That makes the F-JY route a per-part investment, so it suits families of rings where the same form repeats across high volume.

• Confirm whether the profile should be generated or formed in one pass
• For forming, choose the blank angle and width that matches the ring feature
• For generated profiles, select SNMN or TNMN with a radius suited to the finish required
• For groove features, use RPMT round inserts or the grooving series

Setting up the operation

• Keep the depth of cut inside the finishing window for the chipbreaker in use
• Run dry or under full flood cooling; bearing steel is hard and thermally demanding
• Check the taper and roundness of the ring across a full batch, not a few parts
• Where the ring is hardened, confirm the hardness stays inside the cermet range, or move to CBN
• Record the form-tool geometry so it can be reproduced exactly on reorder

Related

• SNMN Bearing Ring Turning Inserts — 3 models
• TNMN Bearing Ring Turning Inserts — 3 models
• RPMT Bearing Turning Inserts — 2 models
• F-JY Bearing Insert Blanks — 8 models
• MGMN Cermet Grooving Inserts — 6 models
• TGF32-R Right-Hand Cermet Grooving Inserts — 11 models
• TGF32-L Left-Hand Cermet Grooving Inserts — 11 models

Planning note

Decide first whether the ring form is generated with a standard insert or produced in one plunge with a forming tool. Forming tools use F-JY blanks ground to the ring profile and suit high-volume families with a repeating form; generated profiles use SNMN or TNMN ground inserts. Run dry or full flood and hold the depth of cut inside the finishing window.