How to Achieve High-Precision Metal Part Production Through Metal Injection Molding

To achieve high-precision metal parts production through Metal Injection Molding (MIM), the following key aspects can be addressed:

Raw Material Selection and Preparation: Select metal powders with fine and uniform particle sizes, typically ranging from 2 to 25 micrometers. For instance, the particle size distribution uniformity of 304 stainless steel powder significantly impacts subsequent forming and precision. Additionally, it is essential to strictly control impurity indicators such as oxygen content. Advanced techniques like nitrogen-protected atomization can be employed to reduce oxygen levels and improve powder quality. The selection of binders is also critical, requiring good compatibility with the metal powder and complete removal during the debinding process without leaving impurities that affect part performance.

Mold Design and Manufacturing: High-precision molds serve as the foundation for achieving high-precision parts. Advanced CAD/CAM technology is employed for mold design, precisely planning the dimensions and shapes of mold cavities while accounting for factors such as the shrinkage rate of metal powders during forming and sintering processes, enabling reasonable compensation for mold dimensions. High-precision machining equipment is utilized to manufacture molds, ensuring machining accuracy of mold cavities at the micron level with low surface roughness, thereby guaranteeing part surface quality and dimensional accuracy.

Injection Molding Process Optimization: Precisely control various parameters of injection molding, such as injection temperature, injection pressure, injection speed, and holding time. The injection temperature should ensure good flowability of the feedstock, allowing it to fully fill the mold cavity, but must not be excessively high to prevent decomposition of the binder or oxidation of metal powder. The injection pressure and speed should be moderate to guarantee the dimensional accuracy and density of the parts, avoiding defects such as flash or material shortages. The holding time must be sufficient to compensate for the shrinkage of the feedstock during cooling, minimizing dimensional deviations in the parts.

Debinding Process: Select appropriate debinding methods, such as solvent debinding, catalytic debinding, or thermal debinding, or employ a combination of multiple debinding techniques. During the debinding process, strictly control parameters such as temperature, duration, and atmosphere to ensure the binder is uniformly and gradually removed from the green body, preventing issues like deformation or cracking. This provides a solid foundation for subsequent sintering operations.

High-temperature sintering: During the sintering process, precise control of conditions such as sintering temperature, heating rate, holding time, and sintering atmosphere is essential. High-precision temperature control equipment is employed to minimize temperature fluctuations, ensuring uniform heating across all parts of the component and preventing uneven shrinkage due to thermal gradients. Based on the characteristics of the metal material and the performance requirements of the component, an appropriate sintering atmosphere—such as hydrogen, nitrogen, or vacuum—is selected to facilitate the diffusion and bonding of metal powder particles, thereby improving the component's density and dimensional accuracy.

Quality Inspection and Control: Establish a comprehensive quality inspection system, setting inspection points at every stage of the production process. Utilize precision measuring equipment such as coordinate measuring machines to conduct real-time inspections of part dimensions and shape accuracy. Upon detecting deviations, promptly analyze the causes and adjust process parameters accordingly. Additionally, inspect performance indicators such as surface quality, density, and hardness of the parts to ensure they meet high-precision requirements.