Do you have a need to produce a high volume of a small, complex metal piece or component? Does the usual method of metalworking or machining seem cost prohibitive? Perhaps Metal Injection Molding is the process you are looking for. Metal Injection Molding (MIM) is a process that uses Plastic Injection Molding machinery to create metal components and pieces. The top 6 advantages of Metal Injection Molding are listed here.
Background and Process
The process of Metal Injection Molding began in the 1970s at a company called Parmatech in California. Once refined and patented, the process became popular with manufacturing during the 1980s. Improvements to the process in the 1990s awarded more recognition to the MIM process and the advantages of Metal Injection Molding have increased over the last few decades. Metal Injection Molding has become a $1.5 billion-dollar industry today, with over 500 parts producers worldwide.
The MIM molding process has several steps1. As the image shows, the process begins with mixing the metal powder with a thermoplastic or polymer binding agent. The mixture is granulated into a feedstock material that is then liquefied and injected into the mold. The molded piece is called a “green part”, which then goes through a debinding process to remove most of the binding material from the part using a solvent, heat or a combination of both. The part is now called a “brown part” and is very fragile, but it can be carefully handled. The part is put through a sintering, or high heat and pressure, process. Sintering removes the rest of the binding ingredient, shrinks the product by 20 to 30 percent, and produces the final part1.
Advantages of Metal Injection Molding
Of the many advantages of Metal Injection Molding, the ability to design small, complex parts quickly and efficiently is one of the most important1. Regular metalworking techniques limit the range of designs for small, intricate metal parts. Small details often need to be created with additional machining or other methods. With MIM, molds can be designed to include small details such as holes, threads, and slots all at once. A second design advantage of MIM is the fact that the final product is more like the original design, without the need for additional machining or finishing.
Another advantage is the ability to combine multiple components into one piece with MIM. Regular metal working usually requires the manufacture of separate parts that must be assembled to create the final product. Metal Injection Molding allows separate pieces to be molded into one solid piece, eliminating further machining and assembly, and lowering costs2.
Combining multiple components also lowers production time. Some parts can be molded in as little as 10 seconds2.
A third advantage of Metal Injection Molding is the creation of more complex parts at a high volume of pieces
Without the need for regular metalworking techniques, there’s the possibility of producing 10,000 to 2,000,000 or more parts per year. Parts with irregular shapes, various holes and slots, internal threads, and contours are a great fit for MIM production1.
The range of materials available to use in MIM is also a great advantage. Metals like stainless steels, magnetic alloys, tungsten, high-speed steels, and copper alloys are possible materials. Special metals like titanium alloys, precious metals, and particle composites are also used3. Special alloys, such as super alloy Ni 625 that resists corrosive environments, and H-X that withstands high temperatures, are available for use in MIM.
The strength and density of finished products are also an important advantage of Metal Injection Molding. During the sintering process, the part is heated to temperatures near melting. This process removes any of the binding material left in the part and densifies the part, shrinking it from 20 to 30%. Finished pieces have densities between 93 and 99%6. MIM produced parts are usually as strong, if not stronger, than machined parts.
A final advantage of Metal Injection Molding is the efficiency of the process. MIM has minimal waste. Nearly all, 95-98%, of raw material is shipped as product5. The feedstock is recyclable and is used again, so waste is almost non-existent.
Metal Injection Molding is used in many areas of industry7. Industries that use small, strong and complex parts have grown the MIM business by millions of dollars over the last few decades. For instance, the medical industry uses MIM to produce surgical instruments and implantable devices. The dental industry produces orthodontics, such as seen in this photo.
The automotive industry uses MIM to produce engine parts, steering system parts, and lock parts. The IT and electronics industry makes up about 50% of MIM sales in Asia, producing items such as lightning chargers for phones and fiber optics parts7. The aerospace industry produces engine components and seatbelt parts. Firearms parts are produced with Metal Injection Molding and parts of Department of Defense equipment are MIM produced. Consumer products include eyeglass parts, camera equipment parts, and musical equipment pieces.
The process of Metal Injection Molding offers many advantages for producing high volumes of small, complex metal parts or components. The advantages of Metal Injection Molding include design flexibility, a variety of materials, reduced processing and assembly costs, and a strong quickly and efficiently produced product.
Product applications of MIM products occur in many areas of industry and use, including in the medical and dental field, automotive and aerospace industries, and as consumer products. If you need to produce a high volume of a small, complex metal piece or component, then the advantages of Metal Injection Molding can work for you.
Metal Injection Molding Sources
- Optimim: https://www.optimim.com/mim-process
- Chinasavvy: https://www.mobile.chinasavvy.com/industrial/metal-injection-molding.html
- Sandvik: https://www.materials.sandvik/en/products/metal-powder/metal-injection-moulding-mim/mim-advantages/
- 8 reasons: https://medium.com/amt-mim/8-reasons-metal-injection-molding-could-be-suitable-for-you-d6d8280f377
- Industrialmetalcasting: http://www.industrialmetalcastings.com/casting_metal_injection_mold.html
- PIM: http://www.pim-international.com/metal-injection-molding/metal-injection-moulding-introduction/
Size comparison: http://s3files.core77.com/blog/images/2014/01/0metalinjectionmolding004.jpg
Powder to part: https://www.industr.com/en/EM-Magazine/__image/a/2298544/alias/xl/v/1/c/18/ar/flexible/fn/MIM_04.jpg
Combination process: https://upload.wikimedia.org/wikipedia/commons/thumb/8/88/OBE-Metallpulverspritzguss-Abb2.jpg/220px-OBE-Metallpulverspritzguss-Abb2.jpg