MIM vs Investment Casting

Which is the better technology for manufacturing metal parts, MIM or Investment Casting?

Compared to investment casting, which represents one of the oldest applied metal molding processes, Metal Injection Moulding or MIM is a relatively new technology. MIM technology became known in the 1980s – however, even in the 1990s, many companies involved in the manufacture of metal parts were still using investment casting. Especially in the 1980s, there were still doubts about the metallic integrity of parts produced by MIM, which was mainly applied in the manufacture of plastics. To this day, investment casting is considered as the main precision technology, and MIM as a complementary technology that is mainly used for the manufacture of small parts.

Similarities and differences between Investment Casting and MIM

Both technologies are applied to manufacture small-sized parts that are notable for a more complex structure or design and therefore traditional industrial technologies such as forging cannot be used. There may even be parts that need both technologies, investment casting and MIM, to be manufactured correctly.

One of the main differences between investment casting and MIM is the materials to which they can be applied. In general, the investment casting process allows for a wider variety of materials, as the MIM process can only be performed with alloys of a higher melting temperature. Materials such as aluminum, for example, do not work efficiently with MIM.

When to use each technology?

In addition to the materials to be processed, the decision between microfusion and MIM depends on other basic factors:

• In addition to the materials you want to work with, the decision between investment casting and MIM depends on other basic factors: the size of the part, the complexity of the structure and the tolerances it allows, as well as the number of parts you want to manufacture. The ideal part for the MIM process has a length of less than 100 mm and is produced in batches of more than 5000 pieces.

• In general, we can say that most of the parts with a final weight of less than 15 grams (depending on the material) are produced with MIM, since this technology allows thinner structures and has a higher efficiency in the use of materials and energy. However, there are still designers who, even for smaller parts, rely more on investment casting, as it is still considered the most robust technology.

• Traditionally, at Ecrimesa Group, 90 percent of the parts weighing more than 100 grams are manufactured with investment casting, since, at that size, the cost of the fine powder used in the MIM process is too high, as well as the energy required to produce them. However, due to the experience accumulated with MIM and the quality of the materials used, more and more references weighing more than 100 grams have been manufactured in recent years. The supply of tools required for MIM (e.g. injection molding machines) has also improved, allowing the technology to be applied in more cases. In any case, using investment casting, parts weighing up to 25 kg can be produced, whereas, with MIM, the maximum weight of the final part is 250 grams.

• Finally, there are some additional criteria for deciding between investment casting and MIM. In general, it can be said that the development and production process of new parts is shorter with MIM, since there is no obligation to make several molds and prototypes before starting production, which may be necessary when working with investment casting. In addition, the final part design that starts the MIM process is closer to the final part, and machining processes are saved – typically, parts manufactured with MIM have a very high surface and finish quality.

MIM and Investment Casting at Ecrimesa Group

At Ecrimesa Group we have facilities for both investment casting and MIM, and we also have a design office, where manufacturing processes can be simulated and technical advice is offered on which technology to choose to manufacture a specific part.

We also take advantage of the synergies between the two technologies. Having internalized almost all machining processes, we can accompany and support the customer in all manufacturing steps, from the idea and design to the last steps of the final finishing, including, of course, the choice between the technologies that can be applied.

Learn more about our technologies and installations: