Cermet Tools for Turn-Milling and Combined Machining

A turn-mill centre puts turning and milling in one setup, and cermet suits the arrangement because both operations are finishing operations on the same steel. Koves covers the milling side with the CC-MAX solid cermet end mill programme and a range of cermet milling inserts, so one material can finish the outside diameter and the milled features.

CC-MAX solid cermet end mills

The CC-MAX programme is a set of solid cermet end mills. The model code and the product specifications are published in full, so a cutter can be selected by diameter, cutting length, overall length and shank in a single step.

CCB230 is a two-flute ball nose cutter at a 30 degree helix, used for curved surfaces and blending. CCE345 is a three-flute flat cutter at 45 degrees, used for faces, shoulders and slots. CCR435 is a four-flute radius cutter at 35 degrees, used where a corner radius must be generated.

Cermet milling inserts

For indexable cutters the catalogue offers APMT, RCMT, RCKT, SEMN and SEEN inserts. Each is supplied in KT20 with KCT25 available, and the cutting conditions are published by workpiece material and hardness.

Working a turn-mill part

A typical sequence on a turn-mill centre finishes the outside diameter and any grooves on the turning side, then mills flats, slots or curved surfaces without re-clamping the part. Using cermet for both keeps the material behaviour consistent and avoids mixing tool materials whose wear rates differ.

The RCMT and RCKT round inserts are the flexible choice for milling because a round edge has a strong, continuous cutting edge and can be indexed to a fresh section. APMT inserts, with their positive rake, suit lighter finishing cuts on steel and stainless.

• Turn the diameter with a positive M-grade or G-grade insert first
• Cut grooves with MGMN or TGF32 inserts in the same setup
• Mill flats and slots with CCE345 or an APMT cutter
• Blend curved surfaces with CCB230 ball nose or CCR435 radius cutters
• Keep speeds consistent between the turning and milling operations

Process rules for turn-milling

• Stock up on rigidity - turn-mill centres have long tool overhangs, which amplifies any tendency to chatter
• For helical end milling use down (climb) cutting, as the catalogue recommends
• Use compressed air where chip evacuation is a problem
• To suppress chatter, raise the feed per tooth or the depth of cut rather than lowering them
• Run dry or under full flood cooling, and avoid partial cooling on the milling side
• Keep the workpiece inside the cermet range: steel to HRC45, no duplex stainless, no high-silicon aluminium

Where turn-milling gains

The gain from turn-milling with cermet comes from finishing both features in one setup, with one consistent tool material and one cooling strategy. Fewer setups mean fewer datum changes and fewer opportunities for the finish to drift between operations.

As with any cermet application, the result should be measured on the actual part. The published milling conditions are starting values, and the surface finish and the edge life across a full insert index are the two numbers to record.

The milling speeds for steel run from 170 to 360 m/min with a feed per tooth of 0.1 to 0.3 mm/z across the hardness bands, which leaves enough room to keep the milling and turning operations on one machine running at compatible rates.

Related

• CCB230 CC-MAX Ball Nose End Mill (2-Flute, 30°) — 18 models
• CCE345 CC-MAX Flat End Mill (3-Flute, 45°) — 16 models
• CCR435 CC-MAX Radius End Mill (4-Flute, 35°) — 30 models
• APMT Cermet Milling Inserts — 4 models
• RCMT Cermet Milling Inserts — 4 models
• RCKT Cermet Milling Inserts — 2 models
• SEMN Cermet Milling Inserts — 1 models
• SEEN Cermet Milling Inserts — 1 models
• MGMN Cermet Grooving Inserts — 6 models
• TGF32-R Right-Hand Cermet Grooving Inserts — 11 models

Planning note

Finish the outside diameter and grooves on the turning side first, then mill with CC-MAX cutters or indexable inserts in the same setup. For helical end milling use down (climb) cutting and compressed air for chip evacuation. To suppress chatter, increase fz or ap rather than reducing them.