What are MIM Parts?

Metal injection molding applies raw materials of feedstock, which is combine of fine-powdered metal and binder materials. Then these feedstocks will be molten and formed into different shapes with complex structure in injection molding process. This molding process applies high tolerance and multiple cavities to produce high volume molded parts (green parts) in one step. After molding, we remove binder materials in debinding process (brown parts), and densify metal powders in sintering process. Finally, we will get net-shape metal parts with high density of 98%.

MIM process normally uses feedstock with fine-powered metal particles. Therefore, We can select different feedstock with different metal alloy powders to produce various MIM parts with different metal. Regardless of other implement factors, we are able to produce same structure MIM parts with different metal materials easily. There is only sintering temperature issue to consider for final parts performance without any other additional time and money cost. This is very cost-effective for MIM project in new products development and products performance improvement.

MIM parts have the same physical and chemical properties as raw metal alloys. So any post operations on forging or casting parts can be applied on MIM parts. Such as welding, soldering, hardening, tempering, polishing, machining and milling. All these post-operations will increase MIM parts surface performance of physical and mechanical properties.

In most case, sintered parts can satisfy all customers requirements, such as, tensile strength, yield strength, surface hardness, etc. However, for specific demands, we can apply polishing technology to improve MIM parts surface roughness, heat-treatment to improve hardness, tempering to improve elongation.

Different from other traditional metalworking technologies, powered metallurgy and metal injection molding are both suitable for micro metal parts. However, MIM parts have more complex geometry structure than PM parts.

As we can see in the following picture of micro MIM parts, its length is only 1.46 mm.

MIM technology is suitable for small size metal parts, therefore, MIM parts are small size with higher tolerance than traditional metal components. Normally, MIM parts are applied in Automotive, Electrical, Medical and other industrial devices. Regardless of common mechanical properties’ requirement, tolerance is the key characteristic impact final function performance. MIM parts have tolerance of ±0.3%-0.5% nominally, this can satisfy normal functional demand in most case. Furthermore, for special tighter tolerance, we apply additional secondary operations to improve final MIM parts tolerance as requirements. Otherwise, this will give rise to additional cost and time.

MIM parts have complex structure with less limitation than Die casting, PM, machining, Forging parts. Therefore, metal injection molding technology can produce just one single part without further different parts assembly. In products R&D process, researchers can consolidate different parts into one single parts, in order to save weight, cost and time. Furthermore, parts consolidation will improve MIM parts strength and performance. In fact, MIM parts are more close to original design intent than parts assembly.