A new free-machining additive, MnX, has been reported to improve the machining performance of ferrous powder metallurgy (PM) materials. This work investigated this claim by comparing the performance of three otherwise identical PM materials containing: no additive, conventional manganese sulphide (MnS) additions and the new MnX additive. A turning operation and cutting speeds of 100–250 m/min were used during which cutting forces, tool wear and surface finish were measured. The MnX material was found to exhibit superior performance. However, this was most noticeable at higher cutting speeds and at the lower cutting speeds, differences in performance were substantially reduced. [S0094-4289(00)02004-1]

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