Views: 0 Author: Site Editor Publish Time: 2020-07-21 Origin: Site
In comparison to nozzle drool, material at the nozzle can solidify and restrict and block the flow of material. This is found mostly during the cooling cycle of the process or if the injection molding process is interrupted. This condition is called nozzle freeze-off. Tab. 8. 2 lists causes and solutions for nozzle freeze-off.
| Causes | solutions |
1. Melt temperature that is set too low can cause the material to cool rapidly and freeze off | 1. Running melt temperatures higher will slow the time required for the melt to cool and keep the melt molten longer |
2. Back pressures that are too low do not provide enough mixing to the material to raise the melt temperature | 2. Increasing back pressure will help raise the melt temperature |
3. If the nozzle tip temperature is too low or the nozzle orifice is too small, nozzle freeze-off can happen. Poor control of the nozzle heater can create cold spots at the nozzle, causing freeze-off | 3. Positioning nozzle heaters on the nozzle and maintaining heat control in this area can reduce the risk of freeze-off. Raising the nozzle tip can maintain the higher melt temperature from the barrel preventing freeze-off. Using a larger nozzle orifice size will slow cooling of the material in the nozzle and prevent freeze-off |
4. Insufficient decompression or suck back can rapidly cool material at the nozzle tip and freeze off the nozzle | 4. Using more decompression will force material back into the hotter nozzle |
5. Mold temperatures that are too cold, especially for hot tips in lot runner tools, can freeze-off the melt from entering the cavity hot | 5. Higher mold temperatures will help in keeping the melt front at the tip molten |
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Tuofang company is specialized in designing and manufacturing Plastic Injection.
No. 345 Xinjiang Road, Xinqian Street of Huangyan, Taizhou City, 318020, Zhejiang Province, China
