Kumho's laser tread cutting system offers opportunities in mass production

By David Shaw, ERJ staff

Frankfurt, Germany -- The tyres on display at Kumho's stand at the IAA were produced in about three weeks using a commercial YAG (Yttrium aluminium garnet) laser attached to a  room-sized 5-axis CNC milling machine. It is one of two such machines in the world, but it is at an early development phase, not yet suited to commercial production.

The executive in charge of the project is Rob Dolton, a qualified car designer, based in Kumho's technical centre in the UK. Dolton graduated from the University of Coventry about eight years ago and then worked for Fiat in Italy for a few years, helping to design the visuals of cars. Kumho recruited him about five years ago to work on advanced projects.

The project began about six months ago, when Dolton started working with the German company Gravutex Eschmann International Ltd, located in Glossop, UK. Gravutex is an automotive surface finishing company and has branched out from its origins in etching, into all kinds of metallic finishing for the automotive sector.  One of the Glossop unit's key machine tools is a large milling machine which can be fitted with a powerful metal-cutting laser.

When applied to a tyre, the laser can do anything a conventional milling machine can do, but with incredible resolution and accuracy. The beam can cut around 3mm out of a tyre in a single pass, though the speed of cut depends on the composition of the compound. A carbon black compound will cut more easily than a high silica compound, for example.  

Dolton said a single cut might be 3mm deep, but the system can use multiple passes to achieve a depth of 6mm - 7mm. This is close to the technical limit of the system. It is also close to the depth needed for a commercial passenger car tyre. Dolton said the engineers at  Gravutex are confident they can deliver 7mm of tread depth from the laser system. “there does seem to be a level at which they get problems, but we are told that the limit appears to be 6mm - 7 mm” he said.

The tyres on the IAA stand were first hand-cut with deep grooves and then sent to the laser facility for the shallower cuts. Dolton said the next step is to feed the mill with CAD information to achieve a full tyre tread pattern.

His expectation is to make tyres in the conventional way and then to use the laser to cut an image into the top layer of the rubber, creating a striking visual appearance to trigger shelf appeal in the tyre store.

The tyres are on show at the Frankfurt Motor Show (September 15-27)

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Press release from Kumho