How Does Metal Injection Molding Works

Sometimes you might need complex metal parts for some work concerning your housing devices or vehicular needs. Any delay in its availability can cost you some golden opportunities at hand and even stagnate the work you need to complete. Thus, all you need is a faster solution to your problem.

When it comes to producing metal parts in quick succession, the first solution that comes to the mind of people is Metal Injection molding. Let us understand what metal injection molding is before we delve deep into its working;

What Is Metal Injection Molding?

Metal injection molding results from unimaginable technological innovation that facilitates the capability to ensure the mass production of complex metal parts in succession and continuity. Such a procedure is reliable and helps manufacture products like Golf clubs, parts of cell phones, complicated tools for surgery, and fuel injector nozzles. Parts made from aluminum metal injection molding are a part of various sectors like defense, aerospace, medical lines, dental departments, electronics, automobiles, agriculture, and innumerable more. 

Procedure Of Metal Injection Molding

The process of metal injection molding includes various stages with distinctive working. Following are the stages of working in this sector;

1.Preparation For The Feedstock

A thermoplastic binder and metal powders are the primary raw materials for Metal injection molding. The thermoplastic binder is a temporary support for this process and requires removal once the injection molding is over. The properties of the metal injection products depend on the quality and properties of the powders used.

The procedure begins with working the powder mix with the thermoplastic binder at a higher temperature with the help of a sheer roller extruder or kneader. The resulting product called feedstock gets granulated in the size of a few millimeters.

2. Injection Molding

The injection molding process that works in resemblance with forming plastic parts results in green MIM parts. This procedure facilitates the production of various part geometries that hold similarities with the humongous variety of plastic components. Here the pellets or granules from the compounding procedure get fed to an injection molding machine. Here the granules get heated till it gets sent into a mold cavity under high pressure. The green MIM parts go through a cooling phase. Once it’s cooled, it gets ejected from the mold for a repetition in the process. The entire procedure happens at a temperature of 200 degrees for the binders to melt. The mold cavity increases by 20% in size to make up for the shrinkage in the sintering process. 

3. Removal Of Binders

Next comes the procedure of removing binders with the sole purpose of obtaining parts facilitated by a pore network working in interconnection. This process of removal happens without destroying the shape of any component. 

Even when the procedure of binder removal ends, there might still be some binders in the parts remaining that hold the particles of metal powder together. Such remains find a temporary life as the initial sintering process facilitates rapid evaporation of the binder remains by the pore network. Here the sintering neck starts developing and misplacing the residuals in the metallic parts. 

4. Sintering

The sintering procedure allows the removal of the majority of the pore volumes that remain occupied by the pore binder; as a result of sintering, the parts of Metal Injection molding witness a size reduction. The shrinkage can go as high as 15 to 20% of the total size of the product. Consequently, the size of the metal parts can be easily increased via further developmental procedures. Such procedure is nothing but the conventional processes of metalworking that include surface treatments or heat treatments that work fine in wrought parts or cast. This helps in natural size enlargement.

The preferred procedure is Hot Isostatic Pressing (HIP); when it comes to specific applications such as aerospace, automotive, and medical sectors, the preferred procedure is Hot Isostatic Pressing (HIP). This particular process of Hot Isostatic Pressing helps in the complete removal of any remaining porosity. Considering that the parts of Metal Injection Molding are comparatively smaller, the HIP procedure can be affordable for cleaning critical components or metal parts.     

After the MIM procedure is over, the metal gets its final touches of plating and coating. This results in higher material density, thus improving the characteristics of the metal component. 

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