Embrittlement of plastic shell injection processing
Aug 03, 2021
1. Raw material plastic
(1) The pressure of the injection molded parts is not properly released or not treated.
Anneal the injection molded part, if it is a nylon plastic product, immerse it in warm water.
(2) Injection molded parts are not fully suitable for specific plastics.
If possible, redesign the product to improve the weak section.
(3) Too much recycled material was added.
Reduce the amount of mixed recycled materials and new materials.
(4) Heterogeneous plastic impurities.
Check for impurities in the plastic. Clean the shooting tank thoroughly. Remove the hopper or the material container and clean it thoroughly.
(5) The quality of recycled materials may be poor.
Separate recycled materials and check carefully for signs of impurities. Ensure that dust is removed from recycled materials. Check whether the reuse procedure is strictly implemented.
2. Injection molding machine
(1) The melting temperature is too low.
Warm up the rear area and the nozzle on the injection cylinder. Reduce the screw speed or high-speed rotation to obtain the correct surface speed of the screw.
(2) The plastic is degraded in the injection cylinder, causing the rupture of the plastic molecular structure. Reduce the temperature of the shooting cylinder in all areas. Reduce back pressure. The use of vented injection cylinders ensures that the discharge holes operate correctly and each hole is set to the correct temperature.
(3) The mold filling speed is too slow.
Increase the mold temperature. Maintain a stable gasket on the injection molding machine.
3. Mould
(1) The mold surface is too cold.
Increase the mold temperature. Limit the speed at which the cooling body flows through the mold.
(2) The runner and gate are too small, resulting in excessive shear failure rate during mold filling.
Use full-circle runners and increase runner and gate dimensions to provide acceptable shear rates during the mold filling stage.
