Powder Metallurgy Injection Molding Process Principle

Powder Metallurgy Injection Molding (MIM) is an innovative process that combines powder metallurgy with plastic injection molding. Its core goal is to achieve mass production and precision manufacturing of complex metal parts through the synergistic combination of "metal powder + binder." This process overcomes the limitations of traditional powder metallurgy, which struggles to form complex structures, and plastic injection molding, which lacks sufficient performance. Jiangsu Mimo Metal, an industry leader, has transformed this principle into a highly efficient production solution, empowering precision manufacturing across multiple sectors.

1. Core Principle: Dual Transformation of Carrier-Assisted and High-Temperature Densification

MIM uses a "binder" as a carrier to first impart plastic-like fluidity to metal powder, allowing injection into complex molds. Debinding and high-temperature sintering then fuse the powder into a dense, high-performance metal part. Traditional powder metallurgy relies on pressing, which can lead to uneven filling of complex structures. Plastic injection molding can also produce substandard materials. MIM, however, leverages a "binder-encapsulated powder" system, balancing molding flexibility with metal properties. Jiangsu Mimo Metal, based on this principle, optimizes process parameters to achieve stable production of precision parts. II. Four Core Processes and Jiangsu Mimo Metal's Practice

1. Raw Material Preparation: Uniform Feeding is the Foundation

High-purity, 1-20μm fine-particle metal powder (such as stainless steel or titanium alloy) is mixed with a binder (polymer, plasticizer, and lubricant) in appropriate proportions to create the "feedstock." Jiangsu Mimo Metal strictly controls the powder particle size distribution and mixing temperature (100-200°C) to ensure uniform coverage of the powder by the binder, preventing material shortages and air bubbles during subsequent injection, and laying the foundation for high-quality parts.

2. Injection Molding: Mold Forming and Prototyping

The feedstock is fed into the injection molding machine barrel, heated and melted, and then pushed into the precision mold cavity under high pressure of 50-200 MPa. After cooling, the "green part" is removed. Jiangsu Mimo Metal designs the mold to match the part's precision (within a tolerance of ±0.005mm) and dynamically adjusts temperature and pressure based on the feedstock's fluidity to ensure green part integrity and meet the molding requirements of complex structures (such as micropores and threads). 3. Debinding: Removing the Carrier and Preserving the Skeleton

The green body first undergoes solvent debinding (soaking in n-hexane to remove 30%-70% of the binder) or acid-catalyzed debinding, followed by thermal debinding (heating at 1-5°C/min to remove any residue), to form a "brown body." Jiangsu Mimo Metal utilizes a composite debinding process to minimize deformation, preserve the intact skeleton structure, and ensure stability during subsequent sintering.

4. Sintering: High-temperature Densification is Key

The brown body is heated to 70%-90% of the metal's melting point (e.g., 1300-1450°C for stainless steel) in a protective atmosphere (hydrogen/nitrogen/argon) or in a vacuum. The temperature is maintained, allowing the powder particles to diffuse and fuse, shrinking the part by 10%-20%, resulting in a density exceeding 95%. Jiangsu Mimo Metal precisely controls sintering parameters to avoid part deformation and coarsening, ensuring the strength and precision of the finished product. III. Summary

MIM principles revolve around uniformity, formability, and compactness. Jiangsu Mimo Metal has transformed these principles into mass production through process optimization. This highlights MIM's advantages: adaptability to complex shapes, high material utilization (waste rate <5%), and high production efficiency. The company provides precision metal parts for the automotive, electronics, and other sectors, promoting the industrialization and application of powder metallurgy injection molding technology.