A method of manufacturing called Metal Injection Moulding (MIM) blends the strength and solidity of hard metals with the flexibility of plastic moulding. The feedstock for this method is made by combining metal powders with polymer binders, heating it, and injecting it into a mould. The item is cooled, next the binder is removed by a debinding process, and finally the metal particles are fused together to form a dense, strong final product through sintering.
Despite its growing popularity in various industries, including automotive, aerospace, medical, and consumer electronics, MIM comes with its own set of advantages and disadvantages.
1. Complicated shapes of parts: MIM allows us to produce parts with complicated shapes and fine details that would be difficult, if not impossible, to achieve with traditional metal working methods such as machining or casting. This capability opens new design possibilities for engineers and designers.
2. High Volume Production: Once the tooling is created, MIM can produce large quantities of parts relatively quickly and consistently, making it ideal for mass production. The economies of scale can significantly reduce the cost per part, especially for complex shapes.
3. Material Variety: A wide range of metals can be used in MIM, including stainless steel, titanium, tungsten, and various alloys. This versatility allows manufacturers to select the optimal material for each specific application based on properties like strength, durability, and corrosion resistance.
| Metal Injection Moulding Powders | |
| Stainless Steel | Common stainless steels like 316L and 17-4 PH are frequently used in MIM for their corrosion resistance and mechanical properties. |
| Tool Steels | Materials like M2 tool steel are used for their hardness and wear resistance. |
| Low Alloy Steels | Alloyed steels can be employed for specific applications that require enhanced properties. |
| Titanium | Titanium alloys are used when lightweight and high strength are crucial. |
4. Accuracy and Consistency: MIM parts have high dimensional accuracy and consistency from part to part, which reduces the need for secondary operations. This precision is crucial for components in industries where tight tolerances are a must, such as in medical devices or aerospace components.
5. Efficient Material Usage: MIM minimizes waste compared to subtractive manufacturing processes since the metal powder can be fully utilized within the mold. This efficiency can lead to cost savings, especially with expensive materials.
Pro Tip: the best metals for MIM are those with greater melting temperatures, including carbon steel and stainless steel. On the other hand, volatile, reactive, easily oxidized, and poisonous metals should be avoided.
1. High Initial Costs: The upfront costs for MIM, including tooling and setting up the production process, can be higher than expected. This makes MIM less cost-effective for small production runs and more suited to high-volume manufacturing.
2. Limitations on Part Size: MIM is generally used for small to medium-sized parts. The process can become less feasible and cost-effective for producing large parts due to limitations in injection moulding equipment and the sintering process.
3. Material Properties: While MIM parts are strong and have good mechanical properties, they might not achieve the same level of performance in certain applications as parts made from wrought materials or forged parts, especially in terms of grain structure and isotropy.
4. Post-Processing Requirements: Even though MIM parts have high dimensional accuracy, some applications may require additional post-processing, such as machining or surface finishing, to meet specific criteria. This can add to the overall production time and cost.
5. Binder Removal and Sintering Challenges: The ‘debinding’ and sintering processes are critical steps in MIM and can introduce challenges such as distortion or defects in the parts if not properly controlled. This aspect of the process requires careful optimization and quality control.
To produce tiny to medium-sized metal parts with complex geometries, metal injection moulding provides a unique mix of design flexibility, material choices, and efficiency. The benefits of the technique must be evaluated against its preliminary expenses, spatial constraints, and particular difficulties related to material characteristics and post-processing. Because MIM’s advantages greatly exceed its drawbacks for a wide range of applications across several industries, it is the recommended option for precision component manufacture in huge volumes.
Looking to produce custom metal injection moulded parts? Contact the HLH team to leverage decades of vast injection moulding expertise. Simply submit your CAD designs and project details via our site contact form, and our team will get back to you with a quote within 48 hours.
