- 學位論文
應用射出壓縮成型技術於金屬粉末成型之研究
Study of Metal Powder Molding by Using Injection Compression Technology
摘要
金屬粉末射出成型(Metal Powder Injection Molding, MIM)為結合塑膠射出成型與粉末冶金的近淨形(Near Net-Shape)成型技術。製程包括由粉末與塑膠黏結劑之混煉、模具設計、射出成型、至後製程之脫脂、燒結與二次加工，涵蓋多項製程，獲得穩定品質實屬不易，尤其在射出階段產生之內應力與粉膠分離等缺陷，等到脫脂與燒結後產品產生翹曲變形現象時才得知已難補救。因此本研究希望能在射出階段時改善MIM初胚的穩定性，進而提升燒結後的產品良率與機械性質，可以減少材料之浪費。 本研究先針對本研究針對傳統射出不同參數包括射料溫度、射出速度、模具溫度與保壓壓力的條件變化，對不銹鋼金屬粉末射出製程的初胚、溶脫後、燒結後之產品進行不同區域之密度、硬度、平坦度與尺寸穩定性的量測；再針對射出壓縮不同參數包含射壓開模量、射壓延遲時間、射壓所模力的條件變化，對不銹鋼金屬粉末射出製程的初胚、溶脫後、燒結後之產品進行不同區域之密度、硬度、平坦度與尺寸穩定性的量測；最後再比較傳統射出參數、射出壓縮參數與其優化之參數做一比較，並使用電腦化數值控制(Computerized Numerical Control, CNC)切削原316L不鏽鋼的拉伸試棒與傳統金屬粉末射出成型以及加入射出壓縮成型之產品進行機械性質比較。 研究結果顯示，在傳統射出成型參數比較中，可得知當料溫為200oC、射出速度為10%、模具溫度為30 oC與保壓壓力為30%時，所得到的初胚、溶脫後、燒結後的產品密度、硬度、產品尺寸穩定性與產品厚度方向平坦度是最佳；在加入射壓的結果中，可看出當射壓開模量為0.5mm、射壓延遲時間為0.9s、射壓鎖模力為85bar時，所量測到的產品密度、硬度、產品尺寸穩定性與產品厚度方向平坦度是最佳；加入射壓製程的金屬粉末射出成型之產品密度，達到了原鋼材99.5%的緻密程度。
並列摘要
Metal powder injection molding (MIM) is a near net-shape manufacturing method combining plastic injection molding process with powder metallurgy process. Since MIM involves the widespread process characteristic, it often ends with unstable on product quality. Especially, the defect of warpage appears usually after the step of agglutination and de-binding result from the stress occurred in injection molding step. This study investigates the effect of injection compression molding to the traditional metal injection molding on the part density, hardness, flatness, and dimensional stability under several control factors. For this study, at first, the traditional metal injection molding experiment is conducted with different melted temperature, injection speed, mold temperature, and packing pressure for the density, hardness, flatness, and dimensional measurement on different part area of green part, brown part, and the final metal product. Further, the same measurement are checked for the synergy processes between metal injection molding and injection compression molding with several parameters included the gap of mold open, compression delay time, and compression clamping force. In the final, we compared with the part molded by traditional metal injection molding, the synergy process, and the one made by CNC process for the mechanical properties. The result shows that the optimized part properties for traditional metal injection molding are molded on the 200 oC melted temperature, 10% injection speed, 30 oC mold temperature, and 30% packing pressure. By this parameters combined with injection compression molding, it is learned that the greatest part properties are molded by the 0.9s compression delay time, 85bar compression clamping force, and 0.5mm of open gap. Moreover, the metal part density of synergy process is achieved 99.5% compared to the density of original stainless steel.