The Advantages & Disadvantages of Metal Injection Molding
Metal injection molding (MIM) combines the best aspects of both traditional plastic injection molding and powder metallurgy, offering the design freedom and cost-effectiveness of plastic injection molding, with the strength and durability of metal components.
In this blog, we explore the advantages and disadvantages of metal injection molding to help you determine if it’s the right manufacturing solution for your product.
Advantages of Metal Injection Molding
The main advantages of the metal injection molding process are:
- Complex Geometries
- Consistent Quality
- Material Selection
- Density & Strength
1. Complex Geometries
MIM parts can be made with intricate internal structures, thin walls, and complex shapes, making it possible to produce functional and aesthetically pleasing components. In addition to complex geometries, MIM also offers tight tolerances, which is important for ensuring the proper fit and function of the component.
Metal injection molding is considered cost-effective due to several reasons, including reduced labor and reduced waste.
MIM is a highly automated process, which reduces the need for manual labor, compared to traditional metal forming methods. This can result in significant labor savings, especially for high-volume production runs.
The metal injection molding process also generates very little scrap, which reduces the amount of discarded material and the associated costs. The high precision of MIM reduces the need for secondary operations, such as finishing and assembly, which can also result in cost savings.
3. Consistent Quality
Consistent quality is achieved in metal injection molding for the following reasons:
The MIM process is highly automated and repeatable, which ensures that each part produced is exactly the same. This reduces the risk of defects and ensures the parts meet specified design and tolerance requirements.
Consistent Raw Material Quality
The MIM process starts with the creation of a metal powder that’s mixed with a binding material to form a feedstock. Metal powders used in the MIM process are highly consistent in composition and particle size, which reduces variability in the final parts and ensures consistent quality.
Metal injection molding takes place in a controlled environment, reducing the risk of contamination and defects. The high pressure and heat used in the process also eliminate any porosity or inclusions that might be present in the feedstock, ensuring the final parts are of high quality.
4. Material Selection
A wide range of material options are available with metal injection molding, including stainless steel, titanium, and low-alloy steels. This gives engineers the flexibility to choose the best material for their specific application.
5. Density & Strength
MIM parts are produced with a high degree of density, which results in excellent mechanical properties, including strength and hardness. This makes MIM a great solution for components that need to withstand high stress and wear.
Disadvantages of Metal Injection Molding
Regardless of which metal-forming technology you’re using, there will always be disadvantages. The following are some of the disadvantages of MIM technology:
- Start-Up Costs
- Tooling Lead Times
- Design Change Costs
1. Start-Up Costs
The metal injection molding process requires specialized equipment, including an injection molding machine, debinding oven, and a sintering furnace. This equipment can be expensive, especially for companies that are new to the MIM process.
Working with a manufacturer with MIM processes already in place can help alleviate these costs.
2. Tooling Lead Times
The lead time for manufacturing a new mold and producing parts with a new design can be weeks or months, especially for complex parts. This delay can impact production schedules, resulting in increased costs due to the need to meet tight deadlines.
3. Design Change Costs
MIM requires a dedicated mold for each part design and the cost of the mold adds to the overall cost of production. If a design change is required, a new mold must be designed and manufactured, which increases lead times and costs.
Metal Injection Molding in Action
Due to the ability to cost-effectively manufacture large quantities of complex parts, MIM is highly beneficial for many industries, including:
Metal injection molding is commonly used in the production of medical devices such as orthopedic implants (hip replacements, knee replacements, and spinal implants), surgical instruments (scissors, forceps, and retractors), diagnostic equipment (blood glucose meters, breath analyzers, and pulse oximeters), and dental devices (implants, bridges, and crowns), where precision, reliability, and biocompatibility are critical factors.
MIM is also a great option for the production of consumer electronics, such as cell phones, wearable devices, and other electronic components. It’s also commonly used in the manufacture of sporting goods (golf club heads, fishing reels, and ski bindings) and jewelry (pendants, earrings, and bracelets).
Metal injection molding is widely used in the production of automotive components such as rocker arms, turbocharger vanes, shift levers, seat components, brake components, injector nozzles, light housings, and numerous fittings and connectors.
MIM is excellent for the production of engine components (turbine blades, nozzles, and combustion chambers), airframe components (hinges, latches, and actuators), avionics components (connectors, switches, and sensors), and spacecraft components (solar panels, antennas, and structural components).
The strength and durability MIM provides make it a popular production choice for agricultural components, such as tractor parts (gears, bearings, and bushings), implement parts (plow shares, cultivator points, and harrow teeth), irrigation components (nozzles, valves, and couplings), and tools (pruning shears, hoes, and cultivators).
Checklist: Is Metal Injection Molding the Right Choice?
Now that you know a little more about metal injection molding and the industries it's thriving in, here’s a checklist to help you decide whether the metal injection molding process is the right choice for your production:
If you answer ‘yes’ to any of these questions, MIM may be a good fit:
- Volume of production: Are you producing large quantities of parts?
- Part size: Are your parts small and complex in design?
- Precision and consistency: Do the parts need to meet strict specifications and tolerances?
- Production efficiency: Are you looking for a highly efficient production process?
- Complex geometries: Do the parts have intricate designs or functional requirements?
While MIM is a highly efficient and versatile production process, there are some situations where it may not be the right choice.
- Frequent design changes: Do you need the flexibility to make frequent design changes? Due to the use of molds, MIM can be expensive to modify once production has started. This makes it an impractical option for prototyping.
- Lead times: Is quick turnaround an important factor? MIM requires the creation of specialized tooling, including injection molds and binding fixtures. Tooling can take several weeks or even months, depending on the complexity of the part.
By considering these factors, you can ensure that you choose the right production process for your specific needs.
Maximize Your Production with Metal Injection Molding
As you can see, metal injection molding offers a number of advantages over traditional metal forming methods, including complex geometries, cost-effectiveness, consistent quality, and a wide range of material options. However, it also has its limitations, including lead time, parts size limitations, material cost, and surface finish.
When considering MIM for your manufacturing needs, it’s important to weigh the advantages and disadvantages carefully to determine if it’s the right solution for your end-use parts.
Ready to learn more about what metal injection molding can do for your production? Check out our other resources.