Differences between metal powder for MIM and metal powder for traditional PM
author: YITECH
2025-02-22
Exploring the difference between powder metallurgys and metal injection molding, industry experts highlight how these advanced manufacturing techniques offer unique solutions for producing complex metal components, with powder metallurgy focusing on compaction and sintering, while metal injection molding integrates plastic injection molding principles for intricate designs.
Differences between metal powder for MIM and metal powder for traditional PM
Although both MIM (metal injection molding) and traditional PM (powder metallurgy) are based on powder processing technology, there are significant differences in the requirements for metal powder between the two, mainly reflected in powder properties, process requirements and application scenarios. The following is a detailed comparison between the two:
1. Powder particle size
MIM powder:
Smaller particle size: usually in the range of 5-20 microns (or even finer).
Purpose: Fine particles can improve the mixing uniformity of powder and binder to ensure that complex mold cavities can be filled during injection.
Traditional PM powder:
Larger particle size: generally 50-150 microns.
Purpose: Coarse particles are easy to cold press, reduce pressing resistance, and reduce the "elastic aftereffect" after demolding.
Purpose: Coarse particles are easy to cold press, reduce pressing resistance, and reduce the "elastic aftereffect" after demolding.
2. Powder shape
MIM powder:
Spherical particles: The powder is required to be close to spherical to improve fluidity and filling density.
Spherical particles: The powder is required to be close to spherical to improve fluidity and filling density.
Reason: Spherical particles have better fluidity during injection and reduce stress concentration in the mold.
Traditional PM powder:
Irregular shape: mostly sponge-like, dendritic or irregular polygonal.
Reason: Irregular particles form "blank" strength through mechanical bite during pressing, which is convenient for subsequent demolding.
Irregular shape: mostly sponge-like, dendritic or irregular polygonal.
Reason: Irregular particles form "blank" strength through mechanical bite during pressing, which is convenient for subsequent demolding.
3. Powder fluidity
MIM powder:
High fluidity requirements: It needs to be mixed with a binder to form a homogeneous feed, and its fluidity is similar to that of plastic.
Test standard: Commonly used Hall Flowmeter test, the flow rate must be less than 25 seconds/50g.
High fluidity requirements: It needs to be mixed with a binder to form a homogeneous feed, and its fluidity is similar to that of plastic.
Test standard: Commonly used Hall Flowmeter test, the flow rate must be less than 25 seconds/50g.
Traditional PM powder:
Lower fluidity requirements: It relies on mechanical pressure rather than flow filling during pressing, and only needs to meet basic filling properties.
Lower fluidity requirements: It relies on mechanical pressure rather than flow filling during pressing, and only needs to meet basic filling properties.
4. Powder purity and composition
MIM powder:
High purity: low impurity content (such as oxygen content needs to be controlled at <0.3%) to avoid defects during sintering.
Alloying method: Mostly pre-alloyed powder (such as 17-4PH stainless steel) to ensure uniform composition after sintering.
Alloying method: Mostly pre-alloyed powder (such as 17-4PH stainless steel) to ensure uniform composition after sintering.
Traditional PM powder:
Allow certain impurities: The performance can be adjusted through subsequent sintering or heat treatment.
Alloying method: Commonly used mixed element powder (such as Fe-Cu-C mixture), the cost is lower.
Allow certain impurities: The performance can be adjusted through subsequent sintering or heat treatment.
Alloying method: Commonly used mixed element powder (such as Fe-Cu-C mixture), the cost is lower.
5. Process adaptability
MIM powder:
Need to match the binder: The powder needs to be compatible with wax-based or polymer-based binders, and there is less residue after degreasing.
High sintering shrinkage: Because the powder is fine, the sintering shrinkage can reach 15-20%, and the mold needs to be precisely designed.
Need to match the binder: The powder needs to be compatible with wax-based or polymer-based binders, and there is less residue after degreasing.
High sintering shrinkage: Because the powder is fine, the sintering shrinkage can reach 15-20%, and the mold needs to be precisely designed.
Traditional PM powder:
Pressure performance is prioritized: The powder needs to form a high-density green body under high pressure, and the shrinkage after pressing is low (about 1-3%).
Pressure performance is prioritized: The powder needs to form a high-density green body under high pressure, and the shrinkage after pressing is low (about 1-3%).
6. Cost difference
MIM powder:
High cost: The preparation of fine powder (such as gas atomization) is complex and energy-intensive; pre-alloyed powder is expensive.
High cost: The preparation of fine powder (such as gas atomization) is complex and energy-intensive; pre-alloyed powder is expensive.
Traditional PM powder:
Low cost: Coarse powder can be prepared by reduction or mechanical crushing, with a simple process and high raw material utilization.
Low cost: Coarse powder can be prepared by reduction or mechanical crushing, with a simple process and high raw material utilization.
7. Application scenarios
MIM powder:
Complex small parts: such as medical devices (surgical forceps), 3C electronics (mobile phone card trays), clock gears, etc.
High-precision requirements: Part size tolerance can reach ±0.3%, surface roughness Ra<1.6μm.
Complex small parts: such as medical devices (surgical forceps), 3C electronics (mobile phone card trays), clock gears, etc.
High-precision requirements: Part size tolerance can reach ±0.3%, surface roughness Ra<1.6μm.
Traditional PM powder:
Simple structural parts: such as automotive gears, bearing seats, lock parts, etc.
Low-cost and high-volume: Suitable for structural parts with low precision requirements (tolerance above ±0.5%).
Simple structural parts: such as automotive gears, bearing seats, lock parts, etc.
Low-cost and high-volume: Suitable for structural parts with low precision requirements (tolerance above ±0.5%).
8. Final part performance
9. Summary MIM powder:
Designed for high-complexity and high-precision parts, it relies on fine powder and spherical particles to achieve flow filling, but the cost is high and the process is complicated. Traditional PM powder: Aiming at low-cost and large-scale production, it optimizes the pressing performance through coarse powder and irregular particles, but the performance of the parts is limited.
Selection basis: If you pursue complex design, high precision and performance, choose MIM; if you need low-cost and fast mass production of simple parts, choose traditional PM.
Selection basis: If you pursue complex design, high precision and performance, choose MIM; if you need low-cost and fast mass production of simple parts, choose traditional PM.
DongGuan YiTai Electronic Technologies Co.,Ltd
DongGuan YiTai Electronic Technologies Co.,Ltd is a manufacturing service provider located in Dongguan, China.
YiTai specialized in CNC turning machining and sheet metal fabrication mainly. As a member of Hung Mou Group, we focus on the overseas marketing development. And based on our parent company’s manufacturing capability and resources, YiTai also expended machining services such as die casting, injection molding, aluminum profile extrusion, 3D printing, which are committed to providing customers with one-stop purchasing services and experience.
CNC MACHINING , CNC MILLING , CNC TURNING , SHEETMETAL , FASTENER , OTHERS
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