What are the causes of sink marks and voids? Measures such as adjusting molding conditions and product design are necessary.
Resin undergoes volumetric shrinkage during the cooling and solidification process. The high volumetric shrinkage rate, particularly in thicker sections, is a primary factor. The layer that solidifies early after injection on the product surface, referred to as the skin layer in the industry, can lead to voids inside the product under conditions where pressure loss occurs during the cooling process. If the surface solidification layer is thick and robust, voids may form inside the product. Conversely, if the surface solidification layer is thin and soft, sink marks may occur. Additionally, sink marks and voids can occur simultaneously. Measures to mitigate sink marks involve adjustments in molding conditions and product design. 【Methods to Address Molding Conditions】 ■ Increase the internal pressure of the resin ■ Thicken the surface solidification layer to forcibly create voids ■ Use foamed materials to mold without lowering internal pressure *For more details, please refer to the PDF document or feel free to contact us.
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**Countermeasures** ■ Increase the mold temperature to slow down the gate seal (the phenomenon where the gate solidifies and prevents further material from entering). Inject the resin into the mold at high pressure, and extend the time during which the injection pressure is applied to compensate for the delayed gate seal. ■ Set the mold temperature lower to form a thick and sturdy solidification layer, forcibly generating voids, while keeping the injection pressure relatively low. ■ For foamed materials, add a foaming agent to regular molding materials or use a fine foaming molding method. *For more details, please refer to the PDF document or feel free to contact us.*
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For more details, please refer to the PDF document or feel free to contact us.
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We, PLAMO Co., Ltd., have continued to pursue the theme of how to embody the "ideal form" of plastic molded products based on product design technology, mold technology, and injection molding technology with superior cost performance. The unique molding technologies born from the fusion of this orientation and foundational technologies demonstrate their true value as groundbreaking methods that overturn the common sense of plastic molding, leaving no room for others to follow. In the fiercely competitive world of manufacturing, PLAMO continues to challenge itself as a plastic molding manufacturer capable of providing solutions rooted in the creation of new technologies that respond promptly to the needs of the next generation.
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