Cermet Inserts — Frequently Asked Questions

Only within a defined band. Cermet is a finishing material for steel and stainless steel up to about HRC45, and the catalogue states it suits finishing and stable semi-finishing. Where the workpiece is harder than that, or where the cut is genuinely interrupted, CBN remains the appropriate material because it retains much more of its hardness and has higher thermal conductivity. Many shops run both: CBN for the hardest and most demanding hard turning, cermet for the finishing passes below the CBN threshold.

The MOQ depends on the series and on whether the item is a standard stock model, an optional item or an order-production item, since the catalogue marks each model accordingly. Standard stock items can be ordered in small quantities; order-production items and non-standard forming inserts are quoted individually. Sharing the model numbers together with the monthly or annual usage lets the exact quantity be confirmed for the specific item.

Yes. The range includes the uncoated KT20 grade and the KCT25 grade, which is the same Ti(C,N) cermet platform with a nano-scale AlTiN coating. Most turning, grooving, threading and milling series list KT20 as the preferred grade with KCT25 available as an option, so the same insert geometry can generally be ordered coated or uncoated.

Yes, for finishing. The catalogue recommends ferritic, martensitic and austenitic stainless steel finishing with a depth of cut below 0.1 mm, at lower speeds than carbon steel: for example 70-160 m/min in grooving, 60-80 m/min in threading and 30-80 m/min in small-bore work. Duplex stainless steel is not recommended for cermet.

The catalogue includes a grade comparison table that aligns the Koves grades with the cermet finishing classes of the major suppliers, including Sandvik, Iscar, Kennametal, Mitsubishi, Sumitomo, Tungaloy, Kyocera, Dijet, NTK, Seco and ZCC.CT. KT20 and KCT25 sit in the P05-P25 and M10 stainless and steel finishing range. A model number from another supplier can be matched to the closest Koves geometry, and a trial on your own part confirms whether the match holds.

Sample quantities can be arranged for evaluation, subject to the series and the model. Sample requests are reviewed together with the workpiece material, the operation and the intended parameters, because cermet performance depends heavily on the depth of cut, the feed and the cooling method. Sample terms are agreed case by case.

Support covers process and parameter selection as well as product supply. It includes defining and optimising the machining process, selecting cutting parameters and tooling, calculating cycle times, selecting holders and accessories, and designing non-standard tooling. Test reports are produced against the customer's own part so the result at identical parameters is documented rather than asserted.

KT20 is the uncoated grade, specified as Co/Ni 12.5%, WC 20.0% and TaNbC 12.0%, with a 1.5 um grain and HV30 1620 hardness. KCT25 is the same cermet platform with a nano-scale AlTiN coating and a composition of Co/Ni 14%, WC 23.0% and TaNbC 6.0%. KT20 favours edge sharpness, while KCT25 favours wear resistance and tool life in steel, stainless steel and cast iron turning and milling.

Only for light interruption. Cermet is less tough than carbide and less tolerant of thermal shock, so heavy interrupted cuts and roughing are outside its range. The catalogue's guidance for interrupted work is to cut dry where possible, and KCT25 with its coating is positioned for light interrupted cutting. For heavy interruption, a tougher carbide or a CBN grade is the correct choice.

Aluminium can be turned and milled in finishing and semi-finishing, but not when the silicon content exceeds 10%. Grey cast iron and malleable cast iron can be finished with cermet. For high-silicon aluminium an abrasion-resistant tool material is needed instead.