Coating doubles tool life

Paul Boughton

Tooling specialist MAPAL has developed its own type of chemical vapour deposition (CVD) coating that is claimed to double tool life for reamers in even the most challenging applications. In addition to extended life, reamers coated with the new HC418 material produce excellent surface finish with outstanding dimensional tolerance.

The performance capability of single-bladed reamers depends principally on the quality of the cutting edge, which is determined by its geometry and by the quality of the coating. For successful reaming, a tool with a very sharp cutting edge and a hard coating is required. In addition, for optimum performance, the coating must be thin and exhibit good layer adhesion.

MAPAL’s new HC418 coating meets all of these requirements and, thanks to special process control during manufacturing, is also significantly ductile whilst remaining as wear-resistant as standard CVD coatings. The balance between the robustness of the coating and ductility also ensures that reamers with the new coating are suited even for difficult machining scenarios such as interrupted cutting.

The smooth surface finish of the coating minimises friction on the workpiece, which enables the chips to flow off more easily. The high-wear resistance ensures consistency in machining, excellent process reliability and dependable quality as standard.

Practical tests have shown that, compared with ordinary reamers, the tool life for reamers coated with HC418 is more than double when working with high-alloy steels as well with tough cast materials such as spheroidal graphite cast iron (GGG) and vermicular graphite cast iron (GGV). In addition, the tool life is approximately 20% longer with grey cast iron (GG).