金屬粉末射出成型產品之熔合線研究

The Study of Welding Lines on MIM Parts

王鴻晉(Hong-Jin Wang)

指導教授 ： 周文祥

國立臺北科技大學/機電學院/製造科技研究所/碩士(2013年)

https://doi.org/10.6841/NTUT.2013.00227

摘要

本論文探討金屬粉末射出型(Metal Injection Molding；MIM)絞鏈與撞錘產品的熔合線問題及提出其模具設變方案。熔合線為MIM常見之射出問題，若其結合品質不良或者是出現在產品肉厚較薄處，產品就很容易在燒結時從熔合線接合處破裂，造成嚴重的良率問題。
在研究初期為了模擬M2工具鋼粉射料在模穴中的充填情形，尋找到黏度相近的模擬替代材料ABS LG XR-474。經由比對充填模擬與實際短射的流動波前尺寸差異，發現MIM射料在充填初期特有的噴射流現象，是影響實際短射與模擬結果差異的主因，同時也了解產品的熔合線問題成因，絞鏈產品因為產品肉厚差異過大所產生的競流效應，使得熔合線出現在產品肉厚較薄處，而撞錘產品因為其產品所配置過於密集的銷孔，使得熔合線於銷孔與銷孔間聯通。
經由與師長與合作廠商討論所決定的設計變更方案，改變產品的澆口位置，可解決以上產品的熔合線問題，CAE分析顯示，設計變更方案所製作之生胚具有良好的熔合線品質，在模具實務上也易於實行。日後若需要開設新模，本研究的結果將可應用於模具設計上，可減少修模次數，節省生產成本，同時提升產品良率。

關鍵字

金屬粉末射出成型 ； 熔合線 ； 短射實驗 ； 噴射流 ； 競流效應

並列摘要

This study is discuss the reason and solutions of welding line on MIM (Metal Injection Molding) part. The welding line is a common defect of MIM part. If these welding lines combine with poor quality, or emerge from the thinner thickness area of the MIM parts. The MIM parts will get weaker after sintering. It’s broken on the welding lines and damage the part.
At the beginning of the study. In order to simulate M2 feedstock in the filling stage, to find the substituted materials ABS LG XR-474 in the Moldflow. We found that early jetting is the main cause of the actual short shot with the simulation result of huge differences. At the same time, we know the race-tracking effect resulted from uneven thickness of the hinge part. And welding line emerge from the thinner thickness area. The welding lines are link together resulted from these pins are highly concentrated on hemmer part.

Discussing the proposal of mold modification with advisor and the company. To change the gate location and gate type. The CAE simulation indicates the quality of welding lines of the proposal of mold modifications are good. And the mold is easy to build. If there is a need to build a new mold, we can apply these proposal on the mold design. It’s also cut down the frequency in mold testing and fixing. Then, reduce the production costs and improve the yield rate.

並列關鍵字

Metal Injection Molding ； Welding line ； Short shot experiment ； Jetting ； Race-tracking

參考文獻

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