Cracks can be understood as defects caused by filamentary cracks, microcracks, white cracks at the top, cracks and viscous dies of annular parts, and runner drill tools. According to cracking time, demoulding cracking and Application
Cracking (also known as cracking). The former occurs in the demoulding process, while the latter occurs in the testing, storage and application (microcracks in contact with solvent vapor, etc.). Cracking caused by factors
1. In the thin-walled part of the product, the ejection position is selected. The local deformation of the product is large, resulting in the phenomenon of stress whitening or stress cracking.
2. The internal stress is caused by the inclination or imbalance of the ejector.
1. Mold temperature is too low or too high. Mold temperature is too low, plastic cooling too early, poor welding, easy to crack. Mold temperature is too high, when the negative pressure is too large, the plastic is not easy to solidify and come out of the surface of the mould.
2. The injection pressure is too high and the injection speed is too fast. When the pressure is too high and the speed is too high, the plastic filled in the mould is too much and the internal stress is too large.
3. Pressure is maintained for a long time. The cooling time of the parts in the die is too long, and the cold plastic sticks to the core, which produces negative pressure during injection.
4. Inlay and plastic shrinkage are inconsistent, leading to cracking.
5. The mould is going too fast.
(3) Raw materials
1. improper lubricant, release agent or excessive dosage.
2. Brand and grade are not applicable.
(4) Product design
Unreasonable product design leads to local stress concentration or more cracks in weak parts
For example, design is too thin or space heart.
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