INVESTIGATIONS ON HARD COATED REAMERS IN DIFFERENT LUBRICANT FREE CUTTING OPERATIONS

The reaming finishing process sets special high demands on quality and wear resistance of used reamers. Only the best adapted cutting geomet rics and parametric cuts allow to obtain high surface qualities and mi nimum deviations from circular form. Cutting operations carried out fr ee of cooling lubricant will cause an extreme increase in thermic and abrasive load of tools. Details given in this paper will show how, usi ng PVD coatings, it nevertheless is possible to obtain relevant file-p roven tool life results, and certainty of operation in lubricant-free reaming and lubricant-weak reaming of gray cast iron (GG25) and alumin ium alloy (AlSi12). Various are-coatings and coatings deposited by spu ttering are analyzed as to their mechanical properties, and wear behav iour is compared in application. In dry naming of gray cast iron, good tool life could be obtained, even for a high cutting speed of 100 m m in(-1), with modified coating materials (TiAlN, TiAlCN, for instance). These are compared with other coating materials (for instance TiZrN). Cutting of AlSi12 was done successfully with TiAlN- and TiB2-coated r eamers.