How large can you create a MIM component?

When deciding if your part is a good fit for the metal injection moulding process, part size is one of the first determining factors. We are frequently asked, "How large a part can you create with MIM?" The quick answer is, in most cases, under 160 grams. However, it is important to understand how part size affects the cost and efficiency of MIM.

Mould restrictions on part size

The size of a part is not limited by the MIM process itself, but rather by the capacity of the mould. The mould does not change in size, so the larger the parts, the more space they occupy in the mould. For example, if you think of the mould or tool as a sheet of paper, fitting only 2 cavities in the mould rather than 6 or 8—especially as part size increases—will take far longer to produce 100,000 parts and is not nearly as efficient as producing smaller MIM components.

Part complexity

The complexity of a component helps determine which process should be used for mass production to be cost-effective and efficient. Therefore, while our sweet spot is less than or equal to 160 grams, if the part is larger and more complex and would typically require machining, MIM may offer economic savings. To fully utilise the MIM process, Design for Manufacturing (DFM) is one of the best practices our engineers follow to ensure your part does not require expensive secondary operations, which can often represent as much as 80% of the component cost.

Download the MIM Design guide for tips on designing for MIM.

Efficiency with MIM materials

MIM feedstock—which can be customised—is inherently more expensive than average recycled aluminium, so it is not surprising that material cost plays a role in the MIM decision-making process. At OptiMIM, we design our components to optimise component weight and use only the minimum material needed to create the component. With the MIM process, you can add complexity to the component without adding material. In contrast, a larger machined part often results in substantial scrap and waste.

If a component is larger than 160 grams and complex in design, and if the economics are favourable, MIM may be a cost-effective alternative to other casting processes.

MIM is capable of achieving intricate features such as dovetails, slots, undercuts, fins, internal and external threads, or complex curved surfaces—to name a few. MIM can also produce cylindrical parts with unique geometries and greater length-to-diameter ratios than most other casting technologies. To learn more about the capabilities of MIM, contact our engineering team to discuss your project needs in more detail.

Part size related to sintering and debinding

After moulding, sintering and debinding furnaces have strict guidelines regarding mass loading for each batch size of components so that the binding material is removed at a proper—and precise—rate. The larger and thicker the parts, the fewer components you can put into the furnace at one time and the longer it takes to sinter and debind. As time is money, shorter cycle times are far more cost-effective; therefore, less mass (part volume) usually equates to lower process cost and time. Our team of engineers can help modify your design to greatly increase production times. Thin walls and using material only where it is needed can optimise your part for the MIM process.

MIM offers a lower-cost solution for small, complex components that would otherwise require expensive secondary operations. While the process may seem specialised, it is fully utilised by almost every industry, including consumer electronics, medical, automotive, hardware, firearms, and telecommunications.

Did you know?

Part designs can be limited when constrained to traditional metalworking processes. However, with MIM, design engineers have the freedom to create parts by placing material only where it is needed for function and strength. The end result is a complex shape that uses less material and does not have to be machined. To fully utilise the MIM process, contact our engineering team to discuss your part design and gain insight into design for manufacturing and other design criteria, including:

• Sintering supports
• Draft—where and when
• Corner breaks and fillets
• Holes and slots
• External and internal undercuts
• Threads
• Ribs and webs
• Knurling, lettering and logos
• Gating types and locations
• Sink and knit lines
• Minimum and maximum wall thickness
• Flash and witness lines
• Interchangeable mould inserts

MIM offers design and cost solutions

The MIM process offers lower-cost solutions for numerous applications compared with other metalworking processes. While part size does not necessarily determine the MIM process, it is definitely something to consider. If you have a small, complex part that requires higher strength and you want to produce large quantities, your project may benefit from the design freedom and cost solutions that MIM provides. If you are interested in learning more, we suggest you contact one of our design engineers who can guide you through the MIM process and its benefits specifically for your project.