DEVELOPMENT OF ENHANCED GREEN STRENGTH LUBRICATING SYSTEMS FOR GREEN MACHINING

摘要

P/M parts are often machined after sintering to meet tight dimensional tolerances or accommodate design features that cannot be formed during compaction. However, with the advent of high performance materials that exhibit high apparent hardness and strength after sintering, green machining becomes a very attractive process to reduce machining costs and promote competitiveness. Machining parts prior to sintering is now possible by using new lubricating systems containing polymeric lubricants that significantly enhance the strength of green parts as compared to conventional lubricants. The higher green strength reduces the risk of initiating green cracks and/or edge chipping during machining. This study compares green and ejection characteristics of FLC-4608 sinter hardening materials pressed with either a new polymeric lubricating system or a conventional EBS wax lubricant. This comparison was carried out on TR specimens and oil pump gears pressed from 6.7 to 7.1 g/cm~3 on laboratory and production scale presses. Sintered properties of the oil pump gears and part-to-part consistency are also reported.