Metal injection molding

Metal injection molding (MIM) technology, a powder metallurgy used with powder metallurgy methods; it became a separate manufacturing method on its own. Injection molding, usually, complex shaped plastic The material is known as production method. 1920s the traditional plastic applications application of metal and ceramic powders It is developed. This new applied to metal powders Technology as ’powder metal injection molding (MIM) teknoloji known.

Injection method with plastic materials A manufacturing process has been applied for many years It is a method. Almost every day to our lives a new plastic piece with complex shape is included. Most the largest of these parts feature is relatively cheap. Other also for many engineering applications Thermo-plastic materials with sufficient mechanical properties (hardness, strength, high temperatures, etc.) does not have. Although these plastic materials are metal or by adding ceramic additives development. But the real progressive plastic instead, high proportion of metal powder into plastic plastic connection obtained by mixing metal material. Plastic binder as a result of removal only metal A porous skeletal structure remains formed. Here's this skeleton metal sintering as in conventional powder metallurgy. formation of metallic connections and pores metal parts.

Metal Injection Molding (MIM) What is Technology?

Metal Injection (MIM) and complex shaped, high High performance metal parts powder metallurgy and thermoplastic injection to produce is a production method that combines technologies. MIME The process is best applied to small parts (100 to pieces under the gram), plastic injection and zinc much better mechanical than die casting methods Features and metal processing and precision casting methods offers much cheaper production. Commercially implemented since the mid-1970s Metal Injection Molding Process, automotive systems, medicine and dentistry devices, orthodontics, weapons, hardware and lock components and computers and electronic applications. MIME The industry has reached up to 2 billion USD as of 2010 market size is estimated to reach. MIME technology complex and difficult parts in a high quality format and in cases where high quantities are required advantage over other manufacturing technologies

Metal Injection Molding Applications

• Automotive Systems - Steering Columns (Actuators, Ignition Lock Components), Sunroof (Stop Cam), Seat Mechanisms, Solenoids, Fuel Injectors
• Orthodontics - Braces, Bukkal Tubes
• Medicine And Dentistry Devices - Endoscopic Surgery apparatus
• Firearm Components - Trigger, Security Lock, Installation Kami, hike, stye
• Hardware And Lock Parts - Lock Cylinders, Bolts, Lock Language, Sidebar
• Computer And Electronics - Disk Components
• Electrical - Connectors, Switches


Basic steps of Metal Injection Molding process It is shown in Figure 1. Metal powders are hot mixed with organic binders. Can be produced as powder Almost all kinds of metal and metal alloy in MIM It may be used. Unalloyed and low-alloy steels, stainless steels, high-speed steels, copper-based alloys (brass, bronze etc.), nickel and cobalt based super alloys (invar, cauldron, etc.), titanium, magnetic alloys, refractory materials and hard mineral (tungsten carbide) are examples of these materials see the list of supplied materials). Only aluminum and magnesium are beyond them. Thermoplastic as a binder materials (paraffin, antipyrine, wax, naphthalene, peanut oil, stearic and oleic acids, esters etc.), polyacetal (polyoxymethylene) and gelatin derived materials (methyl cellulose, glycerin, boric acid, etc.) are used. Homogeneous and uniformly obtained mixture is granulated by cooling. Material injection with a certain granular size used in presses. The presses used in the injection process are very similar to the machines used in the plastics industry.

Metal Powders

Almost any metal produced as a suitable powder may be processed by MIM. Aluminum, on the surface as an exception, since it prevents sintering due to the oxide layer which is always adhered. It stands out. Many types of metals and alloys, composite structures - low alloy steels, stainless steels, hard metals, magnetic alloys, tool steels, intermetallic materials, super alloys, cemented carbides - MIM technology they are on the list of powders to be used. However, the outlook is more expensive than the most promising candidates in economic terms. This, Unlike alternative processes involved in processing, almost balance the high cost of powder production in the necessary form is accounted for by the fact that it is an auxiliary scrap. Less importance in the case of scrap cheap metals bears. There is so much diversity that bil suitable dust kadar for the production of so many candidates economically should be used.

Metal injection molding

Figure 2: SEM images of sample powders. (a) Water atomized copper. (b) Water atomized iron, (c) Air atomized aluminum. (d) Aluminum atomized by helium. (e) Nitrogen atomized high speed steel. (f) Vacuum atomized Inconel - 100 superalloys. (g) PREP-atomized René 95 super alloy (dendritic structure). (h) Aluminum needles manufactured with a perforated container. Courtesy of Huppmann and Dalal

A number of grain shape is therefore important:
These powders should have as high a metal ratio as possible, which may indicates that they have. Spherical or spherical shaped powders are highest in packaging are preferred. However, the risk of distortion and deterioration of the structure increases during binding removal process (separation process). Average particle size and particle size distribution is also important: Fine-grained powders are more preferred for sintering than coarse-grained powders. But they have many limiting factors.

Metal injection molding
Mixture Preparation :MIM feedstock starts with particles. Reological required for molding features, mechanical properties and connector for use chemical and physical to facilitate removal Features selected based on thermoplastic and metal the powders are mixed in a warm environment. Both are correct Powder, as well as choosing the right connector and cost It acts. This preparation is then granulated feedstock is obtained.

Metal injection molding
Forming:Standard Plastic Injection Molding Machines, Metal Injection Molding used to create components. Injection process at a temperature of about 165 tipik180 ° C the injection cycle is 20 seconds. Injection process A piece of metal and plastic binder called ın Green Part layıc no metallic connections not including parts, taking into consideration shaped in desired geometry and shape. Injection after the examination of parts, weight and intensity controls are performed.

Connector Removal:
Metal injection moldingConnective plastic materials carefully from the structure Removed. This process called decomposition is in two stages. performed in the chemical separation process by dissolving in an organic solvent (solvent) is removed from the structure. Thermoplastic in thermal decomposition process substances low temperature pre-sintering in furnaces.

After removing the connector parts, high powder to a sufficient temperature in a protective environment create a metallurgical bond between particles and heated to form condensation. This process is usually Based on solid state diffusion and / or liquid phase formation realizes the concentration process. Parts Usually according to the size of the mold during sintering They shrink between 15-20% and the resulting the density is 96-98%. Optimum sintering The temperature varies depending on the material. Typically, this value for iron-based materials It is about 1200 .1400 ° C.

Sintering is carried out in the following atmospheres:
Metal injection molding

• Under nitrogen gas
• Under hydrogen gas
• Under nitrogen + Hydrogen gas
• Under vacuum