From 10 to 700 – mixed machining at an unprecedented level

Here the challenges for machining are changing. With the advent of sintered steel in engine production, no ISO indexable inserts were available on the market that met the high demands for machining the aluminium/sintered steel combination.

This is mainly due to the chemical reaction that takes place between the iron alloy and the cast aluminium. Tool manufacturers had to deal with a completely new form of wear. During machining, a solid phase was applied on the insert and caused it to break after a few applications. To counteract this wear and to prevent the chemical reaction, MAPAL developed a completely new cutting material. Using this, mixed machining – for the aluminium/cast iron combination as well as the aluminium/sintered steel combination – is reliably performed. The ISO indexable inserts reliably work in the cast iron or steel part of the crankshaft bearings as well as in the aluminium part.

On the one hand, this leap in development was achieved with modified carbide substrates and optimised micro-and macro-geometries of the insert with adjusted rake angles. On the other hand, it was achieved with a newly developed PVD coating. This is based on a TiAlN alloy with a special dopant. As a result, not only the formation of a built-up edge in the aluminium is prevented, but the cutting material is so resistant to wear and heat that high quality machining of the cast iron/steel part can be achieved.

Depending on the application, customers can choose between ISO indexable inserts available as standard. MAPAL offers four geometries each for the aluminium/cast iron and aluminium/sintered steel combination. In addition, special indexing inserts are available with the new cutting material. The results using the new cutting material are impressive in practice. Previously only ten bearing journal bores were machined from the combination of sintered steel and aluminium with one insert. Now an impressive 700 bores are machined with the new cutting material.