Introduction to Metal Powder Injection Molding Technology for Titanium Alloy

Aug 01, 2023

Metal powder injection molding technology is developed on the basis of powder metallurgy technology, combined with plastic injection technology, achieving nearly 100% utilization of raw materials, and is a near net molding technology. The general operating process is to first mix the prepared powder and binder into granules to make granular feed, then shape the feed on an injection molding machine to form a specific shape of the product body, and then degrease and sinter to obtain the product with the required performance. The advantages of titanium alloy metal powder injection molding are:

Metal powder injection molding

1. Can achieve mass production of small three-dimensional complex shaped parts;

2. Uniform composition, fine structure, and excellent mechanical properties;

3. Easy to add alloy elements to prepare the required materials;

4. Easy to control the microstructure of materials.

In the injection molding process of powder titanium alloy, the design of the binder is a core link. It is responsible for successfully completing the injection of titanium alloy powder in a fluid state throughout the entire injection molding process, and plays an important role in maintaining the shape of the billet until the pre sintering stage. However, the added adhesive also becomes one of the most likely sources of pollutants during the entire injection molding process. In addition, a higher binder content will reduce the filling amount of the powder, which not only causes the shape of the body to collapse after degreasing, resulting in defects such as deformation and cracking, but also increases the sintering shrinkage rate, seriously reducing dimensional accuracy. Product; Although the content of the binder can ensure a high powder filling amount, it is difficult to prepare a feed with good fluidity, and the injection cannot be completed smoothly. Ensuring the balance between the binder content and the powder filling amount greatly increases the difficulty of proxy research in the bonding process. It can be seen that although the binder cannot determine the final composition of the sintered product, its selection and use will directly affect the subsequent degreasing and sintering processes, thereby affecting product quality. Therefore, in the research work of metal powder injection molding titanium alloy technology, the focus is on the bonding technology, which also captures the key issue.

MIM considerations

For components manufactured using other metal forming processes, the ones that are suitable for MIM process are those that require extensive processing setup or assembly operations. The main advantage of MIM is that it can produce metal components with complex geometric shapes without the need for mechanical processing.

The MIM process not only provides significant advantages, but also has specific requirements and characteristics. Firstly, in terms of size, the components must be able to fit in a space the size of a tennis ball. Other processes should be considered for larger components. The product weight should preferably be between 0.1 and 35 grams, with a uniform wall thickness ranging from 0.030 inches to 0.250 inches, and have a self-supporting geometric shape during the sintering process.

The main advantage of MIM is that it can produce metal components with complex geometric shapes without the need for mechanical processing.

Potential metal materials include stainless steel (17-4, 316, 420); Low carbon steel (FN02, FN0205, FN08, 4620, 4140, 8620), titanium alloys, and soft magnetic materials (FeSi3, FN50). It can also be Tool steel, controllable expansion alloy and superalloy.

In terms of material properties, even with the use of polymer adhesives, the material composition is similar to steel parts manufactured in other ways and has a raw steel density of approximately 95% to 99%. The tolerance during the manufacturing process is plus or minus 0.5%. It is possible to achieve stricter tolerances, but it is necessary to add a small amount of material to key features and ultimately achieve feature size or position requirements through precision machining processes.

Next, consider the required annual production volume. Due to the cost of mold making and sample operation, MIM is suitable for higher production volumes. If the output is low, the Fixed cost per unit of product will be too high. Usually, it is recommended to estimate an annual production of 10000 units or higher.

The Injection mold construction process needs a gate; The design and mold plan need to include this. Sharp corners are stress points, so it is best to have larger radius dimensions at these positions. The draft angle in component design should be between 0.5 º and 1 º to assist in component ejection. Both internal and external threads can be formed. Wherever possible, the component design should include a flat surface for sintering. Otherwise, for products with highly precise geometric shapes, customized sintering fixtures are required.

In addition, if necessary, the manufacturing process can include secondary processing of MIM components, such as heat treatment, electroplating, and mechanical processing, most of which are carried out at third-party suppliers.

Some types of components are not suitable for MIM processes: screw machine components, stamping parts, precision stamping parts, forgings, cold heading parts, non ferrous alloys, parts with tolerances less than plus or minus 0.002 inches, and gears.

Collaborate with MIM experts

Qinhuangdao Zhongwei Precision Machinery Co., Ltd. has profound and rich experience in MIM processing, providing many advantages as a manufacturing partner. The internal engineering and technical capabilities of the company include:

Advanced development capabilities and customer support, providing pre quotation for new product design, MIM technical training, and guiding the development of new materials and processes.

The project engineer guides Product development and pre production verification.

For the development of new materials and Product development, the material and process engineers guide the development of mold making, rubber discharge and sintering processes.

Manufacturing engineers guide the production operation of new products in the most effective and consistent manner, and can identify opportunities for using automated operations.

Project/manufacturing engineers lead and guide the production of new products in the most efficient and consistent manner, and explore opportunities for using automated operations.

Quality engineering personnel ensure compliance with all quality expectations and requirements, and support the validation of new product designs.

Metallurgical engineers guide metallurgical Test effort to ensure that the mechanical properties of parts meet the material requirements.

Qinhuangdao Zhongwei Precision Machinery Co., Ltd. already has the largest rubber discharge and sintering production capacity in China, and has a continuously operating sintering furnace. Zhongwei Precision also provides professional knowledge in automation, using robots on all press machines to reduce labor, using automatic control on press machines to reduce labor and improve component consistency, and using separate automation operations and 100% inspection in secondary processing operations such as mechanical processing.

Qinhuangdao Zhongwei Precision Machinery Co., Ltd. manufactures molds internally and performs good maintenance throughout the entire life cycle of the molds, ensuring a service life of up to 1 million times. The company uses local supply sources for secondary processing such as mechanical processing, heat treatment, and component coating to improve the efficiency and responsiveness of the supply chain.

Qinhuangdao Zhongwei Precision Machinery Co., Ltd. also has quality management systems such as ISO 9001, ISO 14001, IATF, and ITAR. Our company has demonstrated excellent tolerance control capabilities, which can achieve a tolerance performance of plus or minus 0.002 inches without secondary processing. And it has recognized good material consistency through the use of BASF catalyst materials, including consistency between batches and operational consistency of components.

To explore more ways to innovate using complex and economical components, please visit the metal injection molding website of Qinhuangdao Zhongwei Precision Machinery Co., Ltd.