Heller Machine Tools has a new process technology for coating cylinder bore surfaces of lightweight automotive aluminum engine crankcases, imparting a durable material that will extend engine life and improve performance.

Typically, lightweight engine blocks use cylinder liners, but there is now a practical alternative in twin-wire arc spraying, a cost-effective technology for coating cylinder bores. Partnering with Daimler AG and other companies, Gebr. Heller Maschinenfabrik GmbH, is working to industrialize the process steps and to develop the technology into a reliable process. It will be marketed globally under the name of Heller CBC (CylinderBoreCoating.) Heller also will integrate the process into high-volume engine production.

The twin-wire arc spraying process continuously melts iron/carbon wires and sprays them onto the cylinder bore surfaces of the lightweight aluminum crankcase with the help of a nitrogen gas flow.  Compared to other thermal coating processes, the CBC technology is cost-effective and technologically superior--a reliable, repeatable, highly controllable economical process that vastly improves the cylinder bore surfaces, reducing wear and promoting long-life.

The spraying particle velocity reaches 60-80 m/s, and spray particle temperatures run up to 2,000°C.

Beside the primary coating process, Heller’s CBC machining process includes fine boring, roughening, finish honing to expose pores, and finish machining.

All these steps are accomplished by a complete manufacturing system consisting of the Heller CBC 200 coating module and the Heller MC20 machining modules. Total cycle time for an 8-cylnder engine, including part loading/unloading, is 5 to 6 minutes. The engine blocks may be directly loaded into the machining module or mounted on a swiveling exchanger.

“Although the technology has only been used for exclusive low-volume series until now, its application in medium-volume production already provides significant competitive advantages compared to existing cylinder lining technologies,” said Vincent Trampus, Heller vice president of Sales. “The technology complies with the production rules and criteria of the automotive industry. Now, it is only a small step to mass production.”