| Popis: |
The reaming finishing process sets special high demands on the quality and wear resistance of reamers. The best adapted cutting geometrics and parametric cuts only allow high surface qualities and minimum deviations from a circular form to be obtained. Cutting operations carried out without a cooling 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 possible to obtain sufficient tool-life results and certainty of operations in lubricant-free reaming of grey-cast iron (GG25) and in reaming aluminium alloy (AlSi12) by using a minimum amount of lubricant for micro-spraying. Various arc coatings and coatings deposited by sputtering are analysed as to their mechanical properties, and wear behaviour is compared in application. In dry reaming of grey-cast iron, a good tool life can be obtained, even for a high cutting speed of 100 m min −1 , with modified coating materials (TiAlN, TiAlCN for instance). These are compared with other coating materials (for instance TiZrN). Cutting of AlSi12 has been achieved with TiAlN- and TiB 2 -coated reamers. |
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