What should be paid attention to when setting the mold temperature?
The temperature of the blow mold shall be guaranteed:
(1) products have higher performance and better dimensional stability;
(2) shorter molding cycle;
(3) low energy consumption;
(4) less waste.
Lower for PE blow molding, the mold temperature (usually take 15-30 ℃), to shorten the cooling time, can use a lower mould temperature (5-15 ℃).However, in the season of high humidity and temperature, when the mold temperature is lower than the dew point of workshop air, the mold cavity will condense, resulting in spots, pockmarks and other defects on the surface of products.For this reason, we should try to reduce the humidity around the blow mold to ensure that the product has good appearance performance under short cooling time.In addition, excessive cooling rate may sometimes lead to defects on the surface of the product, resulting in "frozen" stress and warping of the product, especially when the product wall thickness is large.
For engineering plastics, the mold should be used at a higher temperature to improve the appearance of the product.
Water has high heat transfer performance and is the main cooling fluid used in the blow mold.Hard water needs to be softened before being introduced into the mold cooling channel, because the cooling channel deposits scale and is partially blocked, which will greatly reduce the heat transfer performance.For engineering plastics blow moulds, fluid or electrical heating such as oil is required to provide the required higher temperatures.