Metal injection molding is a net-shape manufacturing process that has a lot of advantages for metal components that are precise and efficient. Basically, it uses the injection molding technology to create solid metal components.
In general, metal injection molding (MIM) is used extensively in agriculture, firearms, and consumer equipment. Earlier, the technique was helpful in shaping ceramic materials. Since the 1970s, the technique has become useful in handling metal material. Now, this method is quite popular in fabricating metals.
What Is Metal Injection Molding?
MIM (metal injection molding) is a process to work with metals and make them precise and efficient. Here, the process mixes fine and powdered metal with binder material. Then, it creates a feedstock. After that, this feedstock goes through a solidification process, which is then shaped to create the final metal product.
You need metal injection molding to make strong, dense, hard, and intricate metal parts with top-end mechanical properties. Moreover, the process can produce large volumes of metal parts at a time. Apart from that, it is also cheaper when you are considering bigger loads.
On the other hand, metal injection molding does not have many design restrictions, unlike other processes. Additionally, you do not need to put together multiple metal parts to create a final output.
Another great aspect of MIM is that it does not produce a lot of waste and scrap. This also means that you can make the most of your money. For instance, ideally, you can use 98% of the metals into usable parts.
Hence, when there is a need for high-volume production, you need this type of injection molding. This way, you can create small and complex parts that are not possible with other methods of creating metal tools. Hence, MIM has a lot of applications in automotive, weaponry, consumer goods, and medical.
How Does Metal Injection Molding Work?
Metal injection molding involves injecting metal material into a mold. However, it is a bit more complicated than it sounds.
Here, the main item is a polymerized metal feedstock consisting of miniscule metal particles with a plastic binder. This item is then injected into the mold at high pressure.
Moreover, when the metal in the mold starts to cool and harden, it is released from the mold and then trimmed as per requirement. However, it does not end here.
The next phase is the “green part” which includes the debinding process. In this phase, the manufacturer removes the plastic binder. Now, what is left is a fragile and porous metal piece, which is called the “brown part.”
Then, the manufacturers put this part into a high-temperature furnace, which fuses the metal particles together (sintering). As a result, the metal part becomes fully dense and free from pores. However, it shrinks a bit.
Hence, many manufacturers allow the metal to shrink and use a bigger mold when they begin the sintering process. So, it is safe to keep the green part 15-20% larger than the finished part.
Finally, after the sintering process ends, the density of the metal in the finished part is 96-99%. In fact, this number is actually impressive when you compare the molding process with other techniques.
Actually, metal injection molding includes the use of refined powders. This helps to decrease the porosity of the metal.
Pros and Cons of Metal Injection Molding
The following are the major pros and cons of metal injection molding:
Pros
You can benefit from the following pros of metal injection molding:
- It is easier to produce intricate metal shapes and complex structures with MIM.
- You can have high dimensional accuracy and repeatability. Hence, it leads to consistent and higher quality.
- It is cost-effective when you produce metal parts in large quantities.
- You can use a wide range of metals to mold.
- There is less waste production and lower energy consumption. Hence, this makes MIM a sustainable option.
Cons
Here are a few cons of metal injection molding that you need to be aware of:
- The initial cost of tools is high.
- MIM is not suitable for all types of metals.
- The sintering process requires careful steps from the operators.
- MIM requires longer lead times than other metalworking processes.
- You cannot create complex 3D geometries with large dimensions.
Summing Up
If you want to manufacture complex and intricate geometries, metal injection molding is one of the best processes to undertake. In fact, it has many applications in automotive, weaponry, aerospace, and medical device production.
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