用先进的温模压制工艺生产高密度汽车零件

高密度压制工艺(温模压制)扩大了粉末冶金零件的应用范围。鉴于一次压制/一次烧结(1P/1S)所达到的密度已超过了7.3 g/cm~3,这种成本可行的零件生产方法,往往是最新高密度汽车零件应用采用的方法。达到较高零件密度的关键的第一步是改进润滑剂与预混合工艺,以将润滑剂的含量减小到预混合粉重量的0.25%。本文详述了新润滑剂系统,能够使润滑剂含量减低到预混合粉重量的0.25%,并使生坯密度高达7.5 g/cm~3左右。除了生坯密度高外,生坯强度也达到了30 MPa左右;并能将压制与生坯零件后续处理时开裂的可能性减小到最小程度。虽然还不能用于所有类型的零件,但在Cloyes Gear已证明,这种新的粉末预混合粉,对于生产汽车的气门机构零件是成功的。将详述开发工作的情况和得到的生产体验,并讨论其优点与局限性。

Production of high density PM automotive components utilizing advanced warm die compaction technology

High density compaction techniques (warm die compaction) has broadened the potential application base for PM components.Because single press-single sinter (1P1S) compaction can now achieve densities in excess of 7.3 g/cm3;this cost effective part production approach is often the preferred methodology for new high density automotive applications.A key initiative in achieving higher part densities is the advance in lubricants and premixing technology enabling reductions in the amount of lubricant required to as little as 0.25％ by weight of the premix.Discussed in this paper is a new lube system that enables the use of lubricant levels as low as 0.25 w/o enabling higher green densities up to approximately 7.5 g/cm3.In addition to the high green densities,green strengths approaching 30 MPa are achieved;minimizing the potential for green cracking during compaction and subsequent green part handling.Although not applicable to all types of parts,this new powder premix has proven successful at Cloyes Gear in the production of automotive valve train components.Details of the development activity and resulting part production experiences will be discussed.A discussion of the benefits and limitations will be also be presented.