In household appliance mold processing, minimizing plastic shrinkage is crucial to meeting customer demands and optimizing production. DAYIN Plastics notes that shrinkage is typically more pronounced in thicker sections of injection-molded parts, such as ribs or protrusions, due to slower cooling in these areas. This slower cooling can lead to sink marks at the junctions, a defect that severely limits the design and molding of plastic products, particularly large, thick-walled items like TV cases and monitor housings.
For consumer electronics and other products where appearance is critical, eliminating sink marks is essential, whereas products with less stringent surface quality requirements, such as toys, may tolerate their presence. The formation of sink marks can be influenced by various factors, including processing methods, part geometry, material selection, and mold design. While part geometry and material selection are typically determined by the raw material supplier and are difficult to alter, there are still many adjustable factors within mold design, such as cooling channel layout, gate type, and size.
For example, the cooling speed of a tubular gate is typically faster than that of a conical gate. This rapid cooling can reduce the cavity fill time, thereby increasing the risk of sink marks. Molding technicians can address shrinkage issues by adjusting processing conditions, with fill pressure and time having a significant impact on shrinkage. During the filling phase, continuing to inject additional material to compensate for shrinkage is an effective strategy. However, a fill time that is too short may exacerbate shrinkage, leading to more pronounced sink marks.
DAYIN Plastic Products Co., Ltd. is a high-tech enterprise dedicated to product R&D, design, manufacturing, and sales services, offering one-stop manufacturing solutions. Founded in 1989, the company specializes in mold making, injection molding, post-processing, and electronic assembly. In addition to providing OEM services, DAYIN also develops its own products for customers to directly customize under private label production. With a 50,000-square-meter production base, 30 years of mold development experience, over 50 R&D personnel, and more than 100 injection molding machines, DAYIN is committed to delivering high-quality manufacturing services.