Metal powder should be fine, spherical, and of high purity, with a low oxygen content.
The powder loading capacity should be controlled at 55% to 65%. If it is too high, it is prone to material shortage, and if it is too low, it is prone to deformation.
The adhesive and powder should be well wetted, and the mixing should be uniform to prevent powder adhesive separation.
The feeding must be thoroughly dried to prevent bubbles and delamination.
2、 Injection molding
Control the injection speed, pressure, and temperature matching to avoid excessive spraying and porosity.
The mold temperature is moderate to ensure complete filling without producing burrs.
Reasonable gate and runner design, smooth exhaust, avoiding material shortage and weld marks.
The weight fluctuation of the green body should be small to ensure consistent shrinkage in the future.
Avoid sharp corners and sudden changes in wall thickness, which may cause cracking during debinding sintering.
3、 Defatting (the most problematic step)
It is strictly prohibited to raise the temperature rapidly. The temperature must be raised step by step and insulated in sections to prevent bubbling and cracking.
Ensure the circulation of atmosphere, timely discharge decomposed gases, and avoid internal pressure explosion.
Complex and slender components should be supported/clamped to prevent collapse and deformation.
Defatting must be thorough, as residual adhesive can cause blackening and foaming during sintering.
4、 Sintering
The sintering temperature and holding time should be precise. Insufficient temperature can result in low density, while excessive temperature can lead to coarse grains.
Control the uniformity of furnace temperature, otherwise there will be large dimensional deviations and severe deformation.
Atmosphere matching material (vacuum/hydrogen/inert) to prevent oxidation, decarburization, and carbonization.
Arrange the furnace neatly to avoid mutual squeezing and adhesion.
Cooling should not be too fast to reduce internal stress and deformation.
5、 Size and deformation control
The mold is enlarged in advance with a shrinkage rate of 15% to 20%, and corrected after actual testing.
Stable whole process technology: same batch feeding, same set of parameters, same furnace sintering.
Special shaped parts and cantilever parts must be positioned using sintering fixtures.
Avoid local excessive thickness and asymmetric structures, which can cause uneven shrinkage.
6、 Common Defect Red Line
Cracks in the green body: mostly caused by injection stress, powder adhesive separation, and improper demolding.
Defatting cracking: Heating up too quickly, poor exhaust.
Sintering deformation: insufficient support, uneven furnace temperature, and uneven shrinkage.
Low density and poor strength: insufficient sintering temperature or inadequate insulation.
Batch traceability: Record the entire process of feeding, injection, degreasing, and sintering parameters.
Regularly check the weight, sintering size, and density of the green body.
Pay attention to metal dust explosion prevention, degreasing waste gas treatment, and high temperature safety.
Powder metallurgy, metal injection molding, powder metallurgy gears
Guangming Group focuses on the research and development of metal forming technology and wear-resistant materials. Its main products include metal compression molding and injection molding powder metallurgy products. The company has a team of high-quality talents, with the founding team originating from the Guangzhou Nonferrous Metals Research Institute, a directly affiliated national and ministerial level scientific research institution. It has rich industry experience and research and development capabilities, providing a continuous source of innovation power for the company's development. The company has successively obtained 5 invention patents and more than 30 utility model patents. It has passed the IATF16949 quality management system, ISO9001-2015 quality management system, ISO14001 environmental management system, intellectual property management system, and obtained international trademark certification. It is an innovative enterprise in Guangdong Province, a small giant enterprise in science and technology in Guangzhou, a member of the Guangdong Powder Metallurgy Industry Technology Innovation Alliance, and an initiator of the Guangzhou Advanced Powder Metallurgy Cluster Promotion Center.
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