Beyond Traditional Methods: Embracing MIM Parts for Innovative Designs

The global metal injection molding (MIM) market is expected to show strong growth over the next several years. Taking advantage of this opportunity will require manufacturers to think beyond traditional methods.

MIM is a precision metal fabrication process that can reduce the need for secondary operations, such as machining. This will unlock extra value for manufacturers.

1. Requirements Analysis

In the context of new product development, there are numerous methods for collecting high-quality requirements. However, they do not guarantee consistency and completeness.

The RDFC is a method for translation of end-user needs into unambiguous, verifiable and feasible system performance specification requirements. It also enables a mechanism to support trade-off analyses between related requirements to maximize mission assurance within cost and schedule constraints. The co-creation of the RDFC with end-users shows that they find the topics and logic flow intuitive, and windows of new discoveries open up during completion of the RDFC.

MIM is ideal for manufacturing near-net shaped parts in medium to high volumes. This includes parts with recessed features, undercuts and threads, as well as complex geometries such as bosses or holes. APP’s application engineers and Ph. D. metallurgists are on standby to work with customers on taking their part design and engineering it into a production capable MIM component. MIM fabrication can also create a wide range of materials and alloy systems.

2. Design Concept

MIM’s fine metal powders allow engineers to design intricate parts that would be impossible with traditional casting methods. This allows manufacturers to innovate products and support the advancement of modern technology.

MIM also provides engineers the opportunity to choose from a variety of metal materials including titanium and complex alloys, making it possible for them to design CAD models that will work with the process. These advantages are particularly helpful for companies in the aerospace industry, which have traditionally been slow to adopt new technology due to the critical nature of engine or sub-system components.

Another benefit of MIM is that the manufacturing process has little waste compared to CNC machining and other processes. The process also offers high accuracy and repeatability. Designers should be aware that MIM parts will shrink slightly from the mold cavity dimensions, requiring them to take this into consideration when preparing CAD models. For example, gates, parting lines and ejector pin marks must be located in the correct positions to minimize mold costs and ensure reliable production.

3. Tooling

As its name implies, tooling is the foundation of a product’s physical production. Similar to how a muffin would not be possible without the proper muffin tin, a product will only be produced in large volume with well-designed and engineered tooling.

A tool is defined as any device that a manufacturer uses to produce a part or product, and can include dies, gauges, molds, jigs, or a combination of these. It is the non-recurring engineering (NRE) phase of the process that coincides with the DFM review.

When designing for MIM, there are specific design considerations such as cam actions, parting lines, gates, and ejector pin marks that must be taken into account. It is best to avoid geometries that overhang, which can cause difficulty during sintering. Also, stepping any external threads flat to simplify the parting line is recommended. Cam actions can increase the lifespan of the part by decreasing the amount of force applied.

4. MIM Production

Metal Injection Molding is a highly scalable production process that can produce small to medium-sized components in high volume. Its ability to deliver net-shape parts eliminates costly, time consuming secondary operations such as machining, thus improving cost efficiency.

The debinding stage of the MIM process removes the binder from a green part to create a porous metal structure, known as a brown part, which can then be fused through the sintering stage. This gives the metal a finished form that imparts its desired mechanical properties.

MIM is also suited for producing complex and precise components in tight dimensional tolerances. Dimensional inspection using coordinate measuring machines (CMMs) and optical comparators can verify the part’s conformance to the specified tolerances, ensuring consistent and accurate results. Likewise, mechanical tests, such as tensile and compression testing, can confirm the part’s material and structural integrity. These tests can also help identify any defects in the parts and allow for their correction.

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