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

Mold Restrictions on Part Size

The size of a part is not limited by the MIM process itself but more so from the size capacity of the mold. The mold does not change in size, so the larger the parts, the more “real estate” they take up in the mold. For example, if you think of the mold or tool as a sheet of paper, if you can fit only 2 cavities on the mold versus 6 or 8, especially as the part size increases, it will take far longer to create 100,000 parts which is not nearly as efficient as smaller MIM components.

Part Complexity

The complexity of a component helps to dictate which process should be utilized for mass production in order to be cost effective and efficient. So, 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 truly utilize 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 our MIM Design guide for tips on designing for MIM.

Efficiency with MIM Materials

MIM feedstock—which can be custom—is inherently more expensive than your average recycled aluminum, so it is not surprising that material cost does play a role in the MIM decision making process. At OptiMIM, we design our components to optimize the weight of the component and only use as little material as possible to create the component. With the MIM process, you can add complexity to the component without having to add material. While a larger part that is machined often results in a lot of scrap and waste.

If your component is larger than 160 grams and complex in design and if the economics are there, then MIM may very well 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 of unique geometries with 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

Second to molding, 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. Remembering that time is money, shorter cycle times are far more cost effective therefore less mass (part volume) usually equates to less process cost/time. Our team of engineers can help to modify your design to greatly increase production times. Thin walls and only using material where it is needed can optimize your part for the MIM process.

[Image: Components being put into sintering furnace]

MIM offers a lower cost solution to small complex components that would otherwise have to endure expensive secondary operations. While the process may seem niche, it is fully utilized by almost every industry including consumer electronics, medical, automotive, hardware, firearms, and telecommunications.

Did You Know?

Part designs can be limited when you’re 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 utilize the MIM process, connect with our engineering team to discuss your part design and gain insight on design for manufacturing and other design criteria, including:

• Sintering supports
• Draft –where and when
• Corner breaks and fillets
• Holes and slots
• Undercuts –external and internal
• Threads
• Ribs and webs

• Knurling, lettering and, logos
• Gating- types and location
• Sink and knit lines
• Min and max wall thickness
• Flash and witness lines
• Interchangeable mold inserts

MIM Offers Design & Cost Solutions

The MIM process offers lower cost solutions for numerous applications compared to other metalworking processes. While part size doesn’t necessarily drive the MIM process it is definitely something to take into consideration. If you have a small, complex part that requires higher strength requirements and you want to produce large quantities, your project may very well 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 walk you through the MIM process and its benefits more specifically to your project.