PVD hard coated reamers in lubricant-free cutting

The reaming finishing process sets special high demands on the quality and wear resistance of reamers. The best adapted cutting geometrics and paramet ric cuts only allow high surface qualities and minimum deviations from a ci rcular form to be obtained. Cutting operations carried out without a coolin g lubricant lead to a sharp increase in thermal and abrasive load of tools. Details given in this paper show how, by using PVD coatings: it is possibl e to obtain sufficient tool-life results and certainty of operations in lub ricant-free reaming of grey-cast iron (GG25) and in reaming aluminium alloy (AlSil2) by using a minimum amount of lubricant for micro-spraying. Variou s are coatings and coatings deposited by sputtering are analysed as to thei r mechanical properties, and wear behaviour is compared in application. Ln dry reaming of grey-cast iron, a good tool life can be obtained, even for a high cutting speed of 100 mmin(-1), with modified coating materials (TiA1N , TiAlCN for instance). These are compared with other coating materials (fo r instance TiZrN). Cutting of AlSi12 has been achieved with TiAlN- and TiB2 -coated reamers. (C) 1999 Elsevier Science S.A. All rights reserved.