Injection Molding
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Low hardness of random copolymer polypropylene injection molded products
Problembeschreibung
The surface hardness test value of the product is lower than standard requirements, and the surface is easily scratched or indented.
Low hardness affects product wear resistance and surface scratch resistance, affecting service performance in products requiring surface hardness.
Ursachenanalyse
(1) Mold temperature is on the low side; low crystallinity of random copolymer polypropylene causes hardness decline
(2) Barrel temperature is on the high side; partial material degradation reduces molecular weight
(3) Holding pressure is insufficient, and product density is on the low side
(4) Cooling time is insufficient, and the crystallization process is incomplete
(5) Improper material grade selection; the hardness index does not meet requirements
Lösung
(1) Appropriately increase mold temperature to the higher value within the 40-80°C range to increase crystallinity
(2) Control barrel temperature at a reasonable value within the 190-260°C range to avoid overheating
(3) Increase holding pressure to 80-120MPa to ensure the product is dense
(4) Extend cooling time to ensure full crystallization
(5) Select a suitable grade, adding nucleating agents if necessary to increase crystallinity
Wichtigste Erkenntnis
Low hardness is mainly caused by insufficient crystallinity or material degradation and needs to be improved by increasing mold temperature and holding pressure.
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