At thicker parts of the plastic mold part, shrinkage, such as ribs or protuberances, is more severe than the adjacent position due to the much slower cooling rate in thicker areas than in the surrounding area. Cooling rate caused by the formation of different connection surface depression, that is, people are familiar with shrink marks. This defect severely limits the design and molding of home appliances injection mold products, especially the large thick-walled products such as television bevel casings and display housings.

There may be one or more reasons for the formation of shrinkage marks, including the processing method, part geometry, material selection and mold design. Geometrical shapes and material choices are often dictated by the raw material supplier and are less likely to change. But there is still a lot of mold maker's concern about mold design that can affect shrinkage. Cooling channel design, gate type, gate size may have a variety of effects. For example, a small gate, such as a tube gate, cools much faster than a tapered gate. Premature cooling at the gate reduces the fill time in the cavity, increasing the chances of shrinkage marks. For the molding workers, adjust the processing conditions is to solve the problem of shrinkage a method. Filling pressure and time significantly affect shrinkage. After the parts are filled, the excess material continues to fill the cavity to compensate for material shrinkage. Too short a filling stage will lead to more shrinkage and eventually to more or greater shrinkage marks. This method alone may not reduce the shrink mark to a satisfactory level, but the molder can adjust the filling conditions to improve the shrink mark.

In addition to modify the mold, the simple solution is to modify the conventional core hole, but you want to make it suitable for all resin is impossible. In addition, gas-assisted methods are also worth a try.