- 學位論文
成型參數對於不銹鋼金屬粉末射出產品密度與機械性質影響之研究
Study on the Density and Product Properties of Stainless Steel Metal Powder Injection Molding Process
摘要
金屬粉末射出成型(Metal Powder Injection Molding, MIM)為結合塑膠射出成型特性與粉末冶金材料狀態、特性的近實形(Near Net-Shaped)成型技術。製程包括由粉末與添加劑之混煉造粒、模具設計、射出成型、脫脂、燒結與二次加工，涵蓋多項工程，獲得穩定品質實屬不易，尤其在射出成型階段，金屬粉末與添加劑結合之材料以高溫、高壓射入常溫之模穴，這兩種比重截然不同的材料，其填充過程充滿變異。因此本研究希望能在射出成型階段時找出射出參數最佳化，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。 本研究針對不同射出參數包括射料溫度、射出速度、模具溫度的條件變化，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與拉伸強度、硬度的量測，由此希望能獲得燒結後產品之最佳化品質研究也對MIM 的計算機輔助工程( Computer Aided Engineering, CAE)分析模擬技術進行開發，藉由材料測試建立MIM配方之剪切黏度資料庫。最後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MIM製程之產品進行機械性質比較。 研究結果顯示，針對不銹鋼金屬粉末射料溫度200oC，射出速度10%，模具溫度30 oC的參數條件，不論是初胚、溶脫後之胚體、燒結後的產品，其密度、硬度及抗拉強度均是最佳的。在分析方面整體金屬粉末密度分佈趨勢與實驗相似。MIM產品與CNC原鋼材機械性能的比較，發現MIM最佳參數的密度達到CNC原鋼材98.7%，抗拉強度達到CNC原鋼材99%與延伸率達到CNC原鋼材92.4%。
並列摘要
Metal Injection Molding (MIM) is a near net shape molding technology which combines plastic injection molding characteristics and powder metallurgy properties. Since MIM involves widely process: granulating, molding design, injection molding, de-binding, sintering and secondary processing, it is hard to have stable quality in final product. Especially, the warpage defect usually appears after de-binding and sintering, which is difficult to remedy. This study aims to improve MIM green part quality in injection molding step, enhance mechanical properties, and increase the productivity of a good final part as well as reduce the waste of material. This study uses several parameters, including melt temperature, injection speed and mold temperature. It measures density, tensile strength, and hardness of green part, brown part and final part in different regions, which are all made by stainless steel using MIM. By studying optimal final part quality through this experiment, it also helps to develop CAE simulation for MIM technology. The material formulation input into the material database in CAE software is established by material testing in advance. Furthermore, in order to compare the mechanical properties of MIM part with a real part made of stainless steel, a block of 316L raw stainless steel was cut in a shape of tensile specimen, same as its counterpart, using Computerized Numerical Control (CNC) cutting machine. These experimental results show that density, hardness, and tensile strength of green part, brown part, and final part are optimal using melt temperature at 200oC, injection speed at 10%, and mold temperature at 30oC. In simulation, metal powder density distribution trends under different settings are similar to experimental ones. Comparing the mechanical properties of MIM product to its CNC-cut raw steel counterpart, the product density, tensile strength, and elongation in MIM under optimized parameters can reach up to 98.7%, 99.0%, and 92.4% of raw steel, respectively. The aforementioned results indicate that MIM can produce a part with properties close to its raw metal product made by CNC.
參考文獻
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