Honing & Coating

Thermal spray coats in cylinder bores of internal combustion engines are high-performance materials of the future. Energy efficient engines with low friction, reduced length and lower weight as well as lower production costs can be achieved due to the new process chain for the manufacture of cylinder bores. To this end, the process chain includes the following processes:

• Mechanical roughing, PTWA coating, overspray jets and honing.

The objective of honing and coating

An overall result of this process chain is a marked reduction in friction, which considerably contributes to reducing fuel and oil consumption. Therefore, a considerable contribution to modern internal combustion engines with a high degree of energy efficiency, low emission values and longevity is also made. 

Principles of Honing and Coating

To achieve a high degree of adhesion when coating, mechanical roughening (pre-treatment) as a variant of  precision boring is required. Mechanical roughening is realized through cutting processes and combined processes consisting of cutting and forming. The following PTWA coating (Plasma Transferred Wire Arc) works with a plasma light arc in which the supply wire is melted and then sprayed onto the cylinder bore. This results in a hard, wear-resistant, ductile and easy to hone cylinder liner coating.

After the thermal coating follows the overspraying jets in which overspray particles are removed from the casting surfaces below the coated cylinder bore by means of a jets of water. Expensive masking is no longer required and the process chain is thereby ready for production.

The subsequent honing, a multiple-step precision machining process, creates the low-friction surface with a high degree of dimensional and form accuracy in the cylinder liner which is needed for the engine.