MIM technology has become the most active cutting-edge technology in the new manufacturing industry

Metal Injection Molding (MIM) is a new near net- forming powder metallurgy technology which is formed by bringing powder metallurgy in modern injection molding technology. Its basic MIM process is: mixing metal powder and binder evenly at first. Then granulating the mixture, and injecting into mould cavity in plastic state to shape product. Using chemical or thermal decomposition method to remove blanks, final products will be obtained finally after sintering.

Compared with traditional process, metal injection molding (MIM) have several advantages like high precision, uniform organization, superior performance, low production costs. Its products are widely used in electronic information engineering, biomedical equipment, office equipment, automotive, machinery, hardware, sports equipment, weapons and aerospace industries. Therefore, the international generally believe the development of metal injection molding will lead to revolutions on part forming and processing, known as "21st century molding technology."

The Parmatech company from California invented this technology in 1973, in early 80s, many European countries and Japan companies also put a lot of effort on technology research, and promoting. Especially in the mid-eighties, industrialized technology development is more rapid, growing at an alarming rate every year. So far, more than 100 companies from the United States, Western Europe, Japan etc… more than a dozen countries and regions, engaged in product development and sales. Japan is very active in the competition, and performs outstanding. Many large companies are also involved in the promotion of MIM, including Pacific Metal, Mitsubishi Steel, Kawasaki Iron and Steel, Kobe Steel, Sumitomo Mining, Seiko, Epson, Datong Steel, and so on. At present, Japan has more than 40 companies specialized in MIM industry. The sales value of MIM product has already surpassed Europe and caught up with the United States. MIM technology has become the most active cutting-edge technology in the new businesses. It’s the world's pioneer metallurgical technology, representing the main development direction of powder metallurgy Technology.

Metal powder injection molding technology combines the plastic molding process, polymer chemistry, powder metallurgy technology, metal materials and other multidisciplinary. It can be said a new change for manufacturing industry. The process not only has the advantages of conventional powder metallurgy technology --no need cutting or cutting less, high economic efficiency, but also overcomes the shortcomings of traditional powder metallurgy such as material uneven, low mechanical properties.
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What kinds of stainless steel parts maby by metal injection molding ?

In recent years, with the development of science and technology, the increasingly diversified fields of stainless steel materials can be further expanded, especially in the stainless steel as stainless steel parts, the complex shape and size of the main material is its development trend.

However, the stainless steel is also difficult to process, because of its high hardness, strength, not suitable for the production of parts of the processing methods, since the former metal injection molding appears so far, the traditional shape of simple stainless steel many excellent performance using precision casting The way to produce more, in this way the production of stainless steel parts of the dimensional accuracy, surface roughness, shape is limited, easy to produce segregation, trachoma has loose loose defects.

In addition to the use of precision casting methods, you can also use die casting - the conventional powder metallurgy method to produce stainless steel parts, but in the use of low concentrations of parts, high porosity, thereby reducing its mechanical, corrosion resistance and appearance, but this methods can only produce simple blank shapes for simple parts forming processes.

Metal injection molding process is the use of fine metal powder microns and some organic binder as injection molding feeds, the method of complex shape parts, even for some three-dimensional parts can be easily achieved in large-capacity production. The use of raw materials for the use of MIM technology for the production of stainless steel metal powder injection parts is a variety of different types of stainless steel fine powder, and the specific binder after mixing and granulation is the desired shape of the injection molded part, Generally do not need too much follow-up processing, dimensional accuracy can reach ±0.3% -0.5%, the density can reach more than 95% of the theoretical density.

These below stainless steel parts mostly produced by metal injection molding

Ignition chamber, inflatable balloon pin, inflatable balloon pin and other cars: mechanical, corrosion resistance and surface appearance of stainless steel metal powder injection parts can be used with considerable stainless steel parts, stainless steel metal powder injection common part is forged parts; space components, small arms Components, orthodontic care wards, surgical instruments, medical gas manifolds, electric toothbrush gears, watch case straps, spectacle frames, cylinders, etc .; days tweezers, pliers, drill bits and other tools, as well as some mechanical "D" Cross "and other joints.

The Lightweight Technology-Powder Metallurgy

The powder metallurgy is a lightweight technology, the most materials saving, process saving technology. Advanced powder metallurgy materials can greatly improve the strength and toughness, reduce the weight, and improve performance. For instance, turbine disk from aircraft engine is all use of the powder alloy turbine disk, because the performance is better, with higher strength, can also reduce the weight.

To develop powder alloy steel is necessarry, such as the oil pipeline if it use of powder corrosion-resistant steel and stainless steel can greatly increase the alloying elements, improve corrosion resistance, can make the oil pipe is relatively thin, but the strength, better corrosion resistance. Most of the connecting rods from Auto are made by powder metallurgy method, in the past with the traditional glaze, the material utilization rate is low, may be less than 50%, with much machining, after used powder metallurgy , forging out is a link, the material utilization rate can reach more than 90%, and the surface fatigue performance is better, the performance can also be improved by weight. 

As we know, metal injection molding(MIM) is a branch of powder metallurgy, this technology is completely suitable for small, complex, mass quantity metal parts production, in many conditions, compared to traditional manufacturing methods, it could achive(or beyond) the same functions to old parts with fewer materials, smaller shapes(glance over some successful MIM cases) . Therefore, the powder metallurgy itself is the lightweight technology.

Limitation of Metal Injection Molding

The basic MIM process steps of metal injection molding are: first select the metal powder and binder in accordance with the MIM requirements, then mix the powder and binder into a uniform feed at a certain temperature using a suitable method. Injection molding, and the obtained shaped billet is subjected to degreasing treatment and sintered to be finalized.

It’s an advanced metal parts manufacturing technology, have several advantages compared traditional methods, these MIM advantages include:

1. High utilization rate of raw materials. Material properties equivalent to wrought alloys;
2. Manufacture small size metal parts (0.02-200g) with complicated geometric shapes directly like producing plastic parts;
3. MIM parts have superior mechanical properties to castings and other PM parts, reflecting fine particle size and high sintered density;
4. Surface roughness up to Ra1.2;
5. Steady quality, high efficiency and economic manufacture of high volume complex parts;
6. No pollution, clean production process.



But Metal Injection Molding also have limitation like other technologies. Here are some disadvantages, or limits of MIM.
1. The material cost of the metal injection molding is high-Compared to powder metallurgy, MIM has higher requirements of raw materials, that makes the cost of MIM is higher.
2. The parts manufactured using this process are typically small-Due to the space of MIM furnace, the most suitable size for MIM is 10-15mm(considered the cost of powder).
3. Quantity of production, as the cost of mould is not cheap, MIM is more suitable for massive production.



With those advantages and disadvantages of Metal Injection Molding, we could know that MIM is a complement technology for traditional methods, and the 3D printing is rising, we would never know what future is. But we always choose the best solution for your metal parts manufacturing.

Commonly used sintering methods for powder metallurgy

As we know, powder metallurgy is made through the production of powder, injection, debinding, sintering, post-treatment process, and sintering is one of the important processes of powder metallurgy, in the sintering process of powder particles to flow, diffusion, melting, recrystallization and other physical chemistry Process, so that the powder body to further dense, to eliminate some or all of the pores. Let me show you powder metallurgy commonly used sintering methods.

1, Liquid phase sintering
If there are two or more components in the powder compact, the sintering may be carried out above the melting point of a certain composition, so that a small amount of liquid phase appears in the powder compact during sintering.

2, Pressure sintering
At the time of sintering, pressure to the powder body to promote its densification process. Pressure sintering is sometimes synonymous with hot pressing, hot pressing is the powder forming and sintering together, directly to the process of products.

3, Activated sintering
In the sintering process using some physical or chemical measures, the sintering temperature is greatly reduced, sintering time significantly shortened, while the sintered body performance has been improved.

4, EDM sintering
The powder body is subjected to direct current and pulsed electric power during the forming and pressing, so that the arc is generated between the powder particles and sintered. At the time of sintering, the pressure is gradually applied to the workpiece, and the forming and sintering processes are combined together.

5, Powder solid phase sintering
Loose powder or green compact in the sintering process does not occur in the composition of the powder sintering method. The solid phase sintering of powder can be divided into two parts: solid phase sintering and multistage solid phase sintering.

The above is about powder metallurgy commonly used sintering methods, powder metallurgy sintering is to compact or loose powder body to further combine to improve the strength and other properties of a high temperature treatment process.

How to choose Metal Injection Molding or Die Casting?

Actually there are so many similarities between Metal Injection Molding(MIM) and Die Casting, Both of these two metal parts producing methods take use of mould, and their producing process are sort of similar, melt metal injected into mold and forming, manufacturers always like take these two producing methods. Therefore, how to define if a metal components project is suitable for Metal Injection or Die Casting?

1.Raw Materials

Commonly used materials for

Die Casting: Aluminum Alloy, Magnesium Alloy, Zinc Alloy, and Copper Alloy in designated circumstance.

Metal Injection Molding: Varieties of Stainless Steels, Iron based.

If we dig deeper, we would find that the biggest diffence between Metal Injection Molding and Die Casting raw materials is melting point, as the melting point is higher of Metal Injection Molding, in Metal Injection Molding, the shape of raw materials is powder, and we would add binders into MIM process, and then sintering process, which is like “oven” process.

As Die Casting usually take formed materials, so we can see that Metal Injection Molding have higher raw materials requirements but more complicated producing process.

2.Size and Weight

The range of Die Casting size is much wider than Metal Injection Molding. It also means Metal Injection Molding have limitation in size nowadays, usually can produce metal parts under 200g.

For the product’s weight of these two manufacturing methods, due to the “binders” wouldn’t remove completely in MIM process, whereby the MIM components would be lighter. In the “lose weight” stream of many industies today, it’s an very important way to achive.

3.Quantity and Costing

Costing is always an important fector when choosing manufacuring process. While the quantity is always an important factor need to be consider. And both of Metal Injection Molding and Die Casting must make mold.

But in generally, when quantity is exceed one specific number, Metal Injection Molding would cheaper than Die Casting.

In any way, the best important reason to choose Metal Injection or Die Casting is raw materials, and specific individual requirements of each metal part project. Last but not the least, take consideration about the quantity for budget control.

ZCMIM, the advanced Metal Injection Molding Manufacturer in China, always offer the best choice for customers not just MIM.