Metal Injection Molding
Application of metal injection molding MIM in the automotive field
Compared with traditional processing methods, MIM technology has the characteristics of high precision, high strength, high shape complexity, diverse materials, and low cost, so MIM technology has been widely used in automobiles.
The MIM parts currently used in automobiles are generally iron-based materials, mainly Fe-Ni alloy steel, Fe-0.4C-1Cr-0.75Mn-0.2Mo alloy steel, pre-alloyed Cr-Mo-C steel, Ni -Cr-Mo-C steel, 316L, 17-4PH, 400 series, HK series stainless steel, Inconel713C nickel-based heat-resistant superalloy steel.
Turbocharger
The turbocharger is mainly composed of a turbine, a pump wheel, a rotor, an impeller, etc. It uses the inertial force generated by the high-pressure exhaust gas discharged from the engine to drive the pump wheel to rotate, and the rotor drives the turbine to rotate to increase the engine intake pressure.
In recent years, the research and development and production of turbocharger MIM parts have become the focus of scientific research, and turbochargers are also one of the iconic parts of MIM manufacturing. Its structure is extremely complex, the working environment is harsh, and the precision is high. However, other processing methods have high cost and difficult to control precision. Turbocharger parts are mainly composed of nickel-based ultra-high temperature alloys, titanium alloys and other materials, which were previously processed by traditional powder metallurgy technology.
BASF in Germany has made a great contribution to MIM turbocharger parts, BASF uses a unique Catamold process to manufacture MIM turbocharger parts. The mechanical strengths of MIM parts and precision casting samples were compared at room temperature, and the results are shown in Table 2. This demonstrates the excellent material properties that can be achieved with the Catamold process.
In China, University of Science and Technology Beijing and Qinhuangdao Zhongwei Precision Machinery Co., Ltd. Qu Xuanhui et al used argon atomized K418 alloy powder as raw material, added self-designed multi-component paraffin-based binder, and adopted injection molding. The complex shape supercharger turbine is prepared by the technology, and the supercharger turbine with dense, uniform structure, excellent mechanical properties, shape and contour that meets the requirements of use and good surface finish is optimized through the subsequent hot isostatic pressing and heat treatment process. It has broken through the key technical difficulties such as the structural design of the supercharger turbine with complex shape, the optimization of injection molding process parameters, the sintering densification and the control of dimensional accuracy, and the comprehensive mechanical properties are significantly improved compared with the casting turbine.
Fuel injector
Many small precision composite parts in automobiles can be manufactured by MIM process. Manufacture of composite parts is generally through forging, precision casting and other methods. When manufactured using the MIM process, it can improve production efficiency, improve accuracy, save materials, reduce processes, and reduce costs.
The electronically controlled gasoline injector on the automobile engine is composed of more than 20 parts, of which the iron core, armature, magnetic guide plate, guide body and other parts constitute the magnetic circuit structure of the injector. These parts are made of soft magnetic alloy materials. made.
Compared with the traditional gasoline injector, the overall performance of the fuel injector manufactured by MIM technology is improved.
India-US MIM Technology Co., Ltd. used MIM to develop and manufacture 4 components of gasoline direct injection pump, the component material is 440C stainless steel, the density ρ>7.65 g/cm3, σbmax is 480MPa, σs is 150MPa, δ is 45%, Rockwell The maximum hardness is 100 HRB, which not only reduces the manufacturing cost by nearly 35%, but also improves the performance of the pump and saves the fuel by nearly 10%-20%.
440C stainless steel MIM seal mounts for direct-fed injector assemblies. This is a complex structural part with multi-angled grooves and top holes. The sealing support made of MIM has a near-net structural shape, ρ is 7.54-7.65 g/cm3, σb is 1600MPa, σs is 1400MPa . The MIM process saves nearly 30%-40% in cost compared to other production processes . At the same time, the cooling piston nozzles used on V-8 cylinder engines are also made with MIM .
Rocker arm for BMW Engine
One is a rocker arm that rotates with the rollers. This is a rocker arm made of low alloy steel that controls the variable valve timing stroke of the engine. It is characterized by its hollow structure and light weight, which is difficult to make by other methods.
Shift Lever
This is a very high volume MIM part for manual transmissions in passenger cars.
The production process of this part is: injection molding, sintering, hardening and assembling the shaft.
The material used is Fe2Ni, and the parts should be carburized and quenched after sintering.
Typical product of engine PIM - intake and exhaust system
Body and Chassis Applications
Name: gear hanger
Material: 316 stainless steel
Name: Seat Adjustment Gear
Material: Iron based powder
Name: Window lifter parts
Name: Brake Parts
Name: Auto Chassis Bobbin
Application: Racing and high-performance vehicle brakes
Name: gear assembly
Application: automatic door and door opening and closing motor drive
Name: seat belt
Application: seat belt locking parts
Sensor
With the advancement of science and technology, the types and functions of sensors used in automobiles tend to be diversified, intelligent and miniaturized. Depending on the application area, sensor housings are used in systems such as engine, chassis, body, and navigation.
Many sensors on the engine, chassis, body, navigation and other systems have been manufactured using the MIM process, such as pressure sensor assemblies, airbag sensor inserts, oxygen sensors, steering sensors, cruise control sensor bases, sensor housings, etc.
Sensing element, threaded port, support ring, sensor kit developed by Qinhuangdao Zhongwei Precision Machinery Co., Ltd. using MIM process Pressure sensor for measuring inlet pressure of pass-through fuel mixture per cylinder of passenger car engine , these parts are made of 17-4PH stainless steel. After heat treatment, σs is 1103MPa, σbmax is 1228MPa, δ is 7%, and parts with hardness between 35-40 HRC are formed close to the final shape.
Airbag is a measure to protect the life of the driver when the car encounters an accident. It can be divided into mechanical type and electronic type.
The mechanical type is triggered by the inertia ball impacting the firing pin, and the electronic type is triggered by the sensitive element. The airbag is composed of D-shaped shaft, embedded tab and ignition pin, all of which are made of MIM17-4PH stainless steel. After heat treatment, σb is 1170MPa, σs is 1100MPa, hardness is between 38-41HRC, δ is 7.0%, density Between 7.60-7.68g/cm3. The dimensional accuracy, stiffness, strength and wear resistance of the parts all meet the requirements of use. Compared with the precision casting process, the MIM process has the advantages of good surface roughness, high tensile strength, realizing the combination of parts, reducing the number of parts, reducing costs, and improving efficiency.
In addition to the above parts, the ignition key, engine rocker arm parts, steering gear U-clip, reverse gear synchronizer, valve lifter, piston ring, combustion chamber cover, car retainer, etc. on the car are all manufactured by MIM process.
Application Prospects of MIM Technology in Automobiles
With the advancement of science and technology, the main direction of automobile development is energy saving, environmental protection, comfort, intelligence and light weight. The application prospect of MIM automobile products in automobiles is huge.
Using MIM technology, tiny automotive parts can be designed as a whole or multiple components, and the MIM process is used for one-time injection molding, so that the parts can achieve the characteristics of miniaturization, integration, and low cost under the premise of satisfying performance. At the same time, it can manufacture parts with complex shapes such as external grooves, external threads, cross holes, blind holes, rib plates, grooves and key pins.
Qinhuangdao Zhongwei Precision Machinery Co., Ltd. uses MIM to manufacture spur gears that control the failure of the rear door of automobiles. Kunshan MagnaClosures is using this new product. Now Qinhuangdao Zhongwei Precision Machinery Co., Ltd. supplies the market every year 720,000 such parts, 30% less cost than using powder metallurgy [13]. At the same time, the company uses MIM technology to develop and produce a fuel control device sector gear, which provides nearly 3 million such parts to Bosch every year.
The application of MIM technology has played an immeasurable role in the lightweight, energy saving, functional integration, and cost reduction of auto parts. The application market prospect of MIM technology in automobiles is very broad.