Metal Injection Molding (MIM) Service
Metal Injection Molding (MIM) facilitates the production of small, complex-shaped metal components with outstanding mechanical properties, which provides superior advantages to your project.
Metal injection molding with elimold
Injection molding is the world’s most popular manufacturing process for plastic components. However, the process can also create metal parts with a few adjustments.
Metal injection molding (MIM) uses metal powder mixed with a binder to create large quantities of precise, repeatable metal parts — ideal for mass production across various industries. The process requires a few extra steps, including granulation, debinding, and sintering.
Elimold is an experienced provider of metal injection molding services and can create molded metal parts for any application.
Advantages of metal injection molding
Metal injection molding offers many advantages over traditional injection molding, with additional benefits provided by the metals and their unique mechanical properties. Specific advantages of MIM include the following:
Molds can be used multiple times, which makes it possible to manufacture large numbers of identical metal parts, from tens of thousands to hundreds of thousands. Metal injection molding can have significant advantages over other metal processing processes, such as CNC machining if high-volume production is required.
Plastic molded parts are favored for their smooth surface finish, and metal injection molding provides similar benefits to metal parts. MIM does not produce unsightly burrs and tooling marks, reducing the need for post-processing.
As long as it’s possible to create the mold itself, metal injection molding can create complex parts with delicate or intricate details. Because the reciprocating screw injects the liquid material with force into the mold, the material reaches every fine crevice.
Metal injection molding is compatible with a range of high-quality engineering materials, and the sintering stage of the process ensures that the molded parts possess good mechanical properties.
Once the feedstock has been injected into the mold, there is no need to cut away any excess material. This makes the process very efficient regarding material usage, with the only material wastage occurring during mold production and debinding.
Although metal injection molding involves multiple stages, it can shorten manufacturing cycles by eliminating extra setups and finishing procedures. Adding internal threads or embossed text, for example, will not drastically increase lead times since these features can be incorporated into the mold (instead of being added to each molded part).
MIM can produce parts with intricate details, thin walls, sharp internal corners, undercuts, and more, all within a single operation.
Combining what would typically require multiple parts made from other processes into a single component is possible with the MIM process. Consolidating the design simplifies your assemblies and reduces costs.
Critical tolerances can be achieved with highly repeatable results. Parts can be post-machined for extra tight dimensions and features.
However, there are some situations where other processes will be a better fit:
- Short Lead Times for New Parts: Each new part requires one or more new molds, which take time to create. 3D printing has faster lead times for new parts that you need quickly.
- Prototypes or Small Production Runs: The price per part will be higher for smaller runs. These processes may work better here, including 3D printing or sheet metal production.
- Large Parts: Parts weighing more than 100 grams or a few inches across are more difficult to produce, so those will be more expensive.
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Metal injection molding materials
Common binder materials
About Metal Injection Molding
Metal Injection Molding (MIM)
Metal injection molding (MIM) is a metalworking process in which finely-powdered metal is mixed with a binder material to create a “feedstock” that is then shaped and solidified using injection molding. The molding process allows high-volume, complex parts to be shaped in a single step. After molding, the part undergoes conditioning operations to remove the binder (debinding) and densify the powders. Finished products are small components used in many industries and applications.
The behavior of MIM feedstock is governed by rheology, the study of sludges, suspensions, and other non-Newtonian fluids.
Due to current equipment limitations, products must be molded using quantities of 100 grams or less per “shot” into the mold. This shot can be distributed into multiple cavities, making MIM cost-effective for small, intricate, high-volume products that would otherwise be expensive. MIM feedstock can be composed of many metals, but the most common are stainless steels, widely used in powder metallurgy. After the initial molding, the feedstock binder is removed, and the metal particles are diffusion bonded and densified to achieve the desired strength properties. The latter operation typically shrinks the product by 15% in each dimension.
Powder metallurgy (PM) covers many ways materials or components are made from metal powders. PM processes can avoid, or greatly reduce, the need to use metal removal processes, thereby drastically reducing yield losses in the manufacture and often resulting in lower costs.
Powder metallurgy is also used to make unique materials impossible to get from melting or forming in other ways. A very important product of this type is tungsten carbide (WC). WC is used to cut and form other metals and is made from WC particles bonded with cobalt. It is widely used in industry for tools of many types, and globally ~50,000t/yr is made by PM. Other products include sintered filters, porous oil-impregnated bearings, electrical contacts, and diamond tools.
Since the advent of industrial production–scale metal powder-based additive manufacturing (AM) in the 2010s, selective laser sintering and other metal AM processes are a new category of commercially important powder metallurgy applications.
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MIM process summary:
Metal Injection Molding works similarly to the other injection molding processes – powdered metal is combined with a binding material and then injected into a mold where it’s left to form and curate. The result is a metal part. The process is ideal for the short and long-run production of metal parts, especially those smaller in size and more detailed in terms of properties. Here’s a closer look at the MIM process:
The first step in the metal injection molding process is determining the material and feedstock used to create the parts. (For more on the material range, see the section near the bottom of this article.) Generally, this consists of finely powdered metals – a powder that is fine enough to create the necessary features. After the metal powder is determined, it’s mixed with a thermoplastic binder (often which takes up 40 percent of the total feedstock), heated so that the metal grains bond with the binder, and then fed into the injection molding machine.
The next step is the molding process, where the material is again heated and then injected into the machine for the molding process, which is the point where the part is created.
Binder Removal: After the part is ejected, the next step is to remove the binder. That’s because the final part is about 20 percent larger than the intended end part. Hence, the binder needs to be removed to get it to its actual size.
The final step in the process involves sintering, where the remaining binder is removed from the part, and the metal is fused to create the part, resulting in a net shape or close to the net shape final part. Further post-sintering operations may also be necessary to properly create the final part, which can add further steps and complexities to the process.
All in all, MIM is comparable to creating products from bar stock metal in terms of tensile strength and design capability. Here’s a further look at the metal injection molding process and whether it’s the right production process for your part run.
Contact one of our specialists today for more information on Elimold metal injection molding and to determine if MIM is the best process for your part run.
Part features like surface texture, threads, text, and logos can all be incorporated into the mold instead of being added after the molding process.