MIM is well-suited for industries that require small and intricate metal components with tight tolerances. These include automotive, surgical tools & medical device components, consumer electronics and industrial, aerospace and defense components.
To produce a MIM part, a powdered metal is mixed with a binder to create what’s called “feedstock.” From there, the part can undergo sintering and debinding.
MIM is a strong process for producing complex-shaped parts that eliminates many steps and assembly associated with other metal production methods. Parts can be molded in a wide range of shapes, sizes, and materials, and surface finish flexibility allows for anything from matte stainless steel to polished components.
A key advantage of MIM is its ability to produce tight tolerances and a high percentage of wrought material density in high-volume runs. This enables parts to be designed and manufactured with complex design geometry without the limitations and costs of machine tooling, while still achieving precision in their dimensions.
Dimensional inspection of MIM components can be performed using coordinate measuring machines, optical comparators, or gauge systems. Testing methods such as tensile, compression, and hardness tests can also be used to verify that the resulting mechanical properties are consistent with the desired specifications. In addition, chemical analysis such as X-ray fluorescence or optical emission spectrometry can help ensure that the final MIM part has the correct elemental composition.
MIM is a great choice for small precision parts with intricate geometry that are difficult to manufacture using any other process. Unlike machining, which often produces parts that have to be ground down and reworked, MIM can produce components with tight tolerances that require minimal post-processing.
The ability to make a wide range of shapes and geometries is also key to the flexibility of MIM. This can eliminate the need for screws, adhesive bonding, soldering or welding, which can save time and money. It can also reduce the weight of a finished product, which is becoming increasingly important for consumer electronics, automotive and industrial products.
Proper design and dimensional inspection are essential for producing high-quality MIM components. Coordinate measuring machines, optical comparators and gauge systems can ensure that the resulting dimensions meet the specified tolerances. Tests such as tensile, compression and hardness testing can verify the strength, ductility and other mechanical properties of MIM components.
Medical devices such as surgical instruments and implants typically require strong materials that can withstand sterilization, abrasion and other types of mechanical stress. MIM offers the ability to create components with complex geometries and a variety of alloys, and it can deliver high-strength parts that are difficult to machine from other metal fabrication methods.
The MIM process produces parts that have extremely tight tolerances. This makes it a good option for automotive and electrical components that need to have precise dimensional control.
Tolerance is critical when designing a MIM part because the material expands and shrinks during the sintering stage, which can have a big impact on the geometry of a component. Tolerances of +-0.3% to +-0.5% can be achieved, which should satisfy most functional requirements. A good MIM design will also include wall thicknesses that are relatively uniform. Wide variations in wall thicknesses can cause a part to sinter unevenly, which leads to distortion.
MIM is an appealing production process for many reasons, including its broad material selection and low waste compared to traditional metalworking methods. However, this appeal comes with a tradeoff — MIM parts can require more post-processing to achieve final performance and appearance requirements.
This is due to the complex processes involved in MIM production, which can include mixing and injection molding, debinding and sintering. Proper control and optimization of these processes can reduce the need for additional post-processing steps to reach a final product that meets functional and quality requirements.
For example, engineers may oversize a mold to accommodate shrinkage that would otherwise require them to make adjustments in the molding or compounding stages of production. This additional work can have a significant impact on the finished product, especially when it comes to mechanical properties such as hardness and durability. Tensile testing provides a good measure of the strength and durability of a MIM part.