Progress in Titanium Metal Powder Injection Molding

Abstract

Metal powder injection molding is a shaping technology that has achieved solid scientific underpinnings. It is from this science base that recent progress has occurred in titanium powder injection molding. Much of the progress awaited development of the required particles with specific characteristics of particle size, particle shape, and purity. The production of titanium components by injection molding is stabilized by a good understanding of how each process variable impacts density and impurity level. As summarized here, recent research has isolated the four critical success factors in titanium metal powder injection molding (Ti-MIM) that must be simultaneously satisfied—density, purity, alloying, and microstructure. The critical role of density and impurities, and the inability to remove impurities with sintering, compels attention to starting Ti-MIM with high quality alloy powders. This article addresses the four critical success factors to rationalize Ti-MIM processing conditions to the requirements for demanding applications in aerospace and medical fields. Based on extensive research, a baseline process is identified and reported here with attention to linking mechanical properties to the four critical success factors.

Titanyum Esaslı Kilitleme Plakalarının Toz Enjeksiyon Kalıplama Süreci

“…1950'lerden sonra bir çok karbür ve seramik temelli karmaşık şekilli parçaların (epoksi, parafin yada selüloz bağlayıcılar kullanılarak) üretiminde TEK kullanılmıştır [4]. Endüstriyel olarak ise 1970'lerde Kaliforniya'da Parmatech firması tarafından ilk defa kullanılmıştır [5]. TEK işlemi plastik enjeksiyon ve toz metalurjisinin birleşmesiyle ortaya çıkmıştır.…”

“…Toz Enjeksiyon Kalıplama (TEK) işleminde reoloji çalışmasından başlayarak, karıştırma, taneleme, kalıplama, bağlayıcı giderme ve sinterleme aşamasına kadar her aşamanın kontrollü yapılması ve ürün kalitesini artırmak için birden çok parametrenin eş zamanlı uygulanması oldukça önemlidir [5][6][7][8]. Ti alaşımı enjeksiyon kalıplama sırasında; eksik dolum, çarpılma, mikro gözenek, çatlak, gözenek ve boşluk, kaynak çizgi hatası, baskı sırasında kırılma, itici pim izleri, kalıba yapışma, ayrışma, kabuk ve katmanlaşma, düzgün olmayan yüzey, pürüzlülük gibi hatalar oluşmaktadır.…”

Powder metallurgy of titanium – past, present, and future

“…Spherical powders are also required for manufacturing Ti components using metal injection molding (MIM) techniques [102]. Typically, AM and MIM processes require particle sizes of powders to be in the range from a few to 100 µm to ensure good flowability of the powder, which is essential for AM and MIM operations.…”

X-ray computed microtomography studies of MIM and DPR parts

“…There are four basic processing steps involved in MIM, namely; feedstock preparation, injection moulding, debinding and sintering. These steps are discussed in greater detail elsewhere (Machaka, Seerane and Chikwanda, 2014;German and Bose, 1977;Machaka and Chikwanda, 2015;German, 2013).Feedstock preparation involves mixing metal powder with a carefully selected composition of polymeric binder materials at a specific temperature. The feedstock is then granulated and injected into a predefined mould die with the desired shape.…”

“…MIM has found widespread applications in the cost-effective production of high-sintered density small parts with complicated shapes and mechanical properties equivalent to those of wrought materials (German and Bose, 1977;Machaka and Chikwanda, 2015;German, 2013). There are four basic processing steps involved in MIM, namely; feedstock preparation, injection moulding, debinding and sintering.…”