What are the reasons and solutions for brittle products during injection molding? Compared with the raw materials of injection molding, the impact properties of plastic parts after injection molding have decreased significantly. This phenomenon is commonly known as embrittlement. The direct reason for embrittlement is that the internal stress of plastic parts is too large.
1. Material
Set appropriate drying conditions before injection molding. If the materials are dried continuously for several days or the drying temperature is too high, although volatile substances and other substances can be removed, it will also lead to material explanation, especially heat sensitive plastics. Secondly, it will reduce the use of recycled materials, increase the proportion of raw materials, and select appropriate materials to make high-strength plastics.
2. Mold Design
Increase the size of the main runner, shunt runner and gate. Sharp corners should be avoided in the runner. Too small runner, shunt runner or gate size and sharp edges will lead to polymer decomposition.
3. Injection Molding Machine
Proper screw should be selected to make the temperature distribution more uniform during plasticization. If the material temperature is uneven, it is easy to accumulate too much heat locally, resulting in the degradation of the material.
4. Process Conditions
First, reduce the temperature of the barrel and nozzle, reduce the back pressure, injection pressure, screw speed and injection speed, reduce the generation of excessive shear heat, avoid polymer decomposition, and reduce the mold opening speed, ejection speed and ejection pressure.
5. Plastic Part Design
During the design, the part in the middle of the plastic part where the fluid flows should not have too thin wall thickness. The product is designed with sharp corners that are prone to stress cracking, inserts, notches or great differences in thickness.
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