MIM is well-suited for production of small parts that are complex in shape and require high performance material. It is also a great choice for production of items that would be difficult to professionally manufacture through other means of fabrication.
In the MIM process metal powders are injected with a binder into a mold cavity and trimmed to release runners. The resulting green parts then go through de-binding which removes the polymers leaving porous brown parts ready for sintering.
1. Increased Efficiency
MIM is a process that is designed specifically for small, complex metal components with tight tolerances. It is an efficient manufacturing method for producing parts with a near net shape, and produces less material waste compared to other metalworking processes such as forging, die casting, and CNC machining.
Once the brown powder is molded into the desired part shape, it goes through a sintering stage where all remaining binder is removed and the metal particles are diffusion bonded together and densified. This process typically shrinks the part by around 15% in each dimension.
After sintering, MIM parts are often subject to additional secondary operations to improve dimensional control, achieve tighter tolerances, and increase mechanical properties. This can be done using heat treating and coating technologies which further reduce the energy consumption of the production process.
2. Less Waste
Metal injection molding can be used to produce parts made from a wide range of materials. However, stainless steel and low alloy steel capture a comparatively large share of the market due to their value added strength, high density and corrosion resistance.
Unlike some other 3D printing processes, which can restrict internal features and channels with a requirement for part ejection, MIM has fewer design constraints. This makes it possible to print parts with complex geometries such as those required for orthopedic implants, and with topologically optimized interiors that maximize strength while eliminating surplus material.
As a result, MIM parts require fewer finishing treatments than parts produced by other fabrication routes, resulting in savings on the cost of plating, machining and heat treatment. For this reason, MIM is also the preferred process for many automotive components, including rocker arms, turbocharger vanes, shift levers and seats. It’s also used in aerospace (strong, lightweight jet engine components) and energy (turbine blades). This is due to its combination of strength, precision and versatility.
3. Lower Carbon Footprint
The MIM process is well-known for its high material efficiency, generating little waste. It is also considered sustainable since it hardly produces any CO2 and consumes comparatively less water.
Metal injection molding is an ideal process for manufacturing complex metal parts. It produces net-shape parts, eliminating the need for expensive machining operations. This allows for a faster turnaround and lower overall production costs.
MIM is especially cost-effective for parts that require tight tolerances. Typically, tolerances of +-0.3% are possible, though machining may be required for tighter specifications.
MIM is used in a wide variety of applications, including automotive components (rocker arms, shift levers, and brakes), medical devices (catheters and laparoscopic instruments), and aerospace and defense industries. The expanding defense budget in the US and the ongoing conflicts in the Middle East have increased the demand for military-grade firearms, driving MIM part consumption. MIM is an ideal technology for this industry due to its high volume production capability and cost efficiency.
4. Increased Flexibility
Unlike molding, which requires a costly mold to be made and subsequently used, MIM printing does not require any tooling. This reduces lead times and allows for rapid changes to digital designs, a crucial benefit during R&D phases.
Additionally, MIM prints in a range of metals including titanium alloys and nickel alloys to ensure optimal strength for parts while meeting specific design or tolerance requirements. This makes it ideal for production of heavy-duty energy components such as turbine blades.
The ability to print in a wide variety of materials also provides flexibility for engineers. When designing a component for metal AM, it is important to maintain even wall thickness and eliminate sharp corners with fillets or radii in order to produce parts that have consistent strength. However, the fact that metal AM can be used to print complex, net-shape parts in a variety of materials and shapes opens the door to a world of innovative energy products that have never before been possible.