Engineers designing components for production need detailed information about the costs associated with various processes to make an informed choice. One such option is metal injection molding.
MIM can be cost-effective for manufacturing medical devices (scissors, forceps, retractors, and other surgical instruments). These parts are small and have thin walls.
Cost of Tooling
While machining, casting, and forging have long been the dominant forms of metal manufacturing, more recent processes like 3D printing and metal injection molding (MIM) are gaining in popularity. The latter is a unique metal forming process that offers a number of advantages over traditional PM.
Unlike conventional machining, MIM delivers components to net shape, eliminating costly machining operations. It also allows for a wide range of finishing options including internal threads, precision and coarse surface finish, knurling, and engraving.
MIM is an ideal choice for complex and delicate parts that cannot be efficiently produced using other methods. These include medical devices, aerospace and defense parts, automotive components, firearms, and consumer products. MIM also provides the flexibility to manufacture parts with tight dimensional specifications that are difficult or impossible to machine. This can be particularly important for products that require articulation or must perform under harsh conditions, such as military-grade weapons.
Cost of Material
MIM is a cost-effective production process for high volumes of small, complex metal parts. The high volume allows companies to amortize costs associated with tooling, and the manufacturing efficiency of MIM makes it less expensive than machining for larger quantities of parts.
The higher the complexity of a part, the more it will likely cost to produce via MIM. Complex geometries that would be difficult or impossible to fabricate using machining are well-suited to MIM, such as parts with cross holes, angle holes, internal threads, splines, undercuts, and more.
MIM is also appropriate for a variety of applications that require near-full density and strong impact toughness, such as eyeglass hinges, cellular phone locks, and automotive and aerospace components. In addition, MIM is ideal for parts that have tight dimensional tolerances and thin-walled geometry. These include medical devices, such as surgical instruments and implantable devices. MIM is compatible with a wide range of ferrous and non-ferrous alloy systems.
Cost of Sintering
MIM allows for a lot of complexity in the part design, but this comes at an upfront cost. This is normally a result of extensive design for manufacturability (DfM) and is weighed carefully against the performance benefits of the final component.
This is particularly important if you are considering metals that require significant machining to achieve the final geometry such as titanium or Inconel. The benefit of MIM is that these costs are offset by the ability to produce parts to net shape, negating the need for secondary operations.
In addition, MIM reduces the waste associated with machining by eliminating the need to trim the excess material and only producing what you need. The cost of the material for the sintering process is significantly lower than that used in machining. These savings are not reflected in the overall MIM price, however, as they are tied to the upfront mold investment. The cost of the sintering process is therefore reduced if you have a low production volume or if the part can be cored out to allow thinner walls sections.
Cost of Assembly
MIM provides an excellent alternative to traditional machining for parts that must be fabricated from strong, hard metals like titanium. Its ability to incorporate features such as internal/external threads, complex profiles, chamfers, and identity marking directly into the park design eliminates the need for these post-processing steps.
In fact, the MIM process can often save on total cost by eliminating the machining time required to create these features. Additionally, MIM allows for the use of cheaper materials than many competing processes.
MIM also offers manufacturers the flexibility to choose from a wide range of high-performance metal alloys. This makes it possible to produce components such as transmission and drivetrain components, which require a combination of strength, wear resistance, and flexibility, using MIM. This includes a broad range of low-alloy steels that can be hardened for superior mechanical properties. MIM parts is also used to make cooling fan components that must have precise dimensional specifications to balance performance and reduce noise.