What steps are involved in the forming process of metal injection molding electronic parts?

What steps are involved in the forming process of metal injection molding electronic parts?

 

Metal injection molding is a small metal part suitable for mass production. Unlike injection molding, these parts can be geometrically complex and have thin walls and details. The metal powder used enables the use of various ferrous and nonferrous metal alloys and material properties (strength, hardness, wear resistance, corrosion resistance, etc.) to be close to those forged metals. Moreover, because the metal is not melted in the MIM process (unlike the metal casting process), the superalloy can be used without any negative impact on the tool life. The common MIM part of metal includes the following contents:

Low alloy steel; stainless steel; High speed steel; Iron pole; Cobalt alloy; copper alloy; Nickel alloy; Tungsten alloy; Titanium alloy.

Metal injection molding electronic parts are found in many industries, including aerospace, automotive, consumer goods, medical/dental and telecommunications. MIM components can be found in mobile phones, sporting goods, electric tools, surgical instruments, and various electronic and optical devices.

The forming process of metal injection molding electronic parts includes the following steps:

Raw material preparation - The first step is to create a powder mixture of metal and polymer. The powder metal used here is more fine (usually 20 microns) than those used in traditional powder metallurgy methods. The powder metal is mixed with a hot thermoplastic binder, cooled, and then granulated to form a uniform raw material. The raw materials obtained are typically 60% metal and 40% polymer (volume).

Injection molding - powder raw materials are molded in plastic injection molding using the same equipment and tools. However, the mold cavity is designed to account for about 20% of the shrinkage in the sintering process. In the injection cycle, the raw material is melted and injected into the mold cavity, where it is cooled and solidified into the shape of the part. A part of the molded "green" is ejected and then cleaned to remove all flash memory.

Degreasing - This step removes the adhesive from the metal polymer. In some cases, the "green" part of the first solvent degrease is placed in water or chemical bath to dissolve most of the adhesive. After this step, thermal degreasing or presintering is performed. A part of "green" is heated in a low-temperature furnace to remove the polymer adhesive by evaporation. As a result, the remaining "brown" metal part will contain about 40% of the empty space through the volume.

The step after sintering is sintering to reduce the empty space by about 1-5%, resulting in a high density of the "brown" part (95-99%) of the metal part in the high temperature furnace (up to 2500 ° F). The inert gas used in the furnace is in the atmosphere and reaches the temperature?? Near 85% of the melting point of the metal. This process will delete the material pores, resulting in a partial reduction to 75-85% of its molding size. However, this shrinkage is uniform and can be accurately predicted. The obtained part retains the high tolerance of the original molded shape, but now it is much higher density.

After the sintering process, no secondary operation is required to improve the tolerance or surface finish. However, like a part of a cast metal, some secondary processes can be carried out to increase functions, improve material properties, or assemble other parts. For example, the MIM part can be machined, heat treated, or welded.

Metal injection molding (MIM) design rules:

When the design part is made with MIM, most of the design rules for plastic injection molding still apply. However, there are some exceptions or additions, such as the following:

Wall thickness - As with plastic injection molding, the wall thickness should be minimized and kept uniform throughout the component. It is worth noting that in the MIM process, reducing the wall thickness not only reduces the material quantity and cycle time, but also reduces the degreasing and sintering time.

Draft - Unlike injection molding, many MIM parts do not require any draft. It is easier to use polymer adhesives from molds than most injection molded polymers in powder material versions. In addition, the MIM components are fully cooled and shrunk around the molding feature before spraying, because the mixture of metal powder needs longer time to cool.

Sintering support - During sintering, MIM components must be properly supported, or they may be distorted because they shrink. By designing the flat surface of the parts on the same plane, the standard flat support tray can be used. Otherwise, more expensive customized carriers can be necessary.

What value-added services can MIM do for you?

machining

Fully automatic CNC machining center and CNC electronic discharge machining (EDM).

heat treatment

To meet the specific hardness requirements of your parts.

ultrasonic cleaning

Thoroughly remove the particles embedded tightly attached to the solid surface.

passivation

Ensure the metallurgical stability of parts by making its surface more passive and corrosion resistant.

surface treatment

There are many types of surface treatment services for your choice.

Qinhuangdao Zhongwei Precision Machinery Co., Ltd. is located in Qinhuangdao Development Zone, Hebei Province

Qinhuangdao Zhongwei Precision Machinery Co., Ltd. is a metal injection molding part specialized in R&D and manufacturing. We are developing and acquiring because the hard work over the years is stronger than all the time. Now, our factory focuses on the trade, scientific research and manufacturing of MIM.

 

Our product line includes tools, medical, hardware, electronics, auto parts, consumer products, textile accessories, etc. More than 95% of the products are exported to Germany, the United States, the Middle East, etc.

As we develop, we will show our great advantages:

Advanced production equipment and quality inspection equipment;

Perfect quality control system;

Rich development experience and manufacturing process;

Perfect sales service network.

"Qualified quality is more important than everything" is our eternal pursuit.