Metal injection molding method

Abstract

The present invention discloses a metal injection molding method, which is adapted to a mold having multiple mold cavities, and includes a feedstock preparation step, a molded articles ejection step, a classification and management step, a wax-based material removal step, a sintering step, and a compacting step. The classification and management step is to classify molded articles according to differences of the molded articles. The sintering step is to sinter the molded articles with sintering parameters. In this manner, tolerance caused by injection molding process is reduced because of the classification and management step and the sintering step, whereby further improving productive rate and quality of products produced from the mold with multiple mold cavities.

What is claimed is: 
     
         1 . A metal injection molding method, adapted to a mold with multiple mold cavities, comprising:
 a feedstock preparation step for mixing metal powder and a binder to produce a feedstock;   a molded articles ejection step for injecting the feedstock into the multiple cavities of the mold so as to shape the feedstock as multiple molded articles, and then ejecting the molded articles from the mold;   a classification and management step for individually managing and classifying the multiple molded articles according to differences among the multiple molded articles;   a wax-based material removal step for cleaning the molded articles with solvents or heating the molded articles to remove the binder;   a sintering step for sintering the multiple molded articles with sintering parameters where the multiple molded articles are placed in a sintering chamber according to classifications of the multiple molded articles; and   a compacting step for compacting the multiple molded articles after being sintered so as to produce end products.   
     
     
         2 . The metal injection molding method of  claim 1 , wherein the differences among the multiple molded articles in the classification and management step include dimensional difference, surface difference, or different mold cavities. 
     
     
         3 . The metal injection molding method of  claim 1 , wherein in the classification and management step the multiple molded articles are classified according to each of the mold cavities. 
     
     
         4 . The metal injection molding method of  claim 1 , wherein in the sintering step the molded articles are being sintered with different sintering parameters according to different classifications of the multiple molded articles. 
     
     
         5 . The metal injection molding method of  claim 1 , wherein in the sintering step the molded articles are being sintered with the same sintering parameters. 
     
     
         6 . The metal injection molding method of  claim 1 , wherein the sintering parameters are set to control a temperature, time, pressure, and atmosphere during sintering. 
     
     
         7 . The metal injection molding method of  claim 1 , wherein after being classified the molded articles of larger size are placed at peripheral portions of the sintering chamber, and the molded articles of smaller size are placed at a middle portion of the sintering chamber.