As a professional injection mold manufacturer, JS Precision Company has been providing high-quality products, high precision, and fast delivery to their customers for years. One of the most common problems in injection molding is sink marks. In this article, we will discuss what sink marks are, what causes them, and how you can avoid them.
Sink marks are the depressions or dents that occur on the surface of a molded plastic part. These marks are caused by uneven cooling or shrinkage of the material during the molding process. Sink marks can be a serious problem, affecting the appearance and functionality of the final product.
So, how do you avoid sink marks in injection molding?
1, Increase the Injection Speed
One of the most effective ways to avoid sink marks is to increase the injection speed. This will help the plastic material to fill the mold cavity more quickly and evenly, reducing the chances of uneven cooling and shrinkage. However, it’s important to note that increasing the injection speed too much can result in other defects, such as flash, so it’s important to find the right balance.
2, Increase the Holding Pressure
Another way to avoid sink marks is to increase the holding pressure. Holding pressure is the pressure that keeps the mold cavity closed while the plastic material cools and solidifies. Increasing the holding pressure will help to ensure that the material is evenly distributed throughout the mold cavity, reducing the chances of sink marks.
3, Increase the Cooling Time
Another factor that can contribute to sink marks is insufficient cooling time. If the plastic material is not allowed to cool and solidify properly, it can shrink unevenly, causing sink marks. Increasing the cooling time can help to ensure that the material is fully cooled and solidified before the mold is opened.
4, Adjust the Gate Location
The gate is the point at which the plastic material enters the mold cavity. The location of the gate can have a significant impact on the likelihood of sink marks. If the gate is located in a thick section of the part, the material may not flow evenly, leading to sink marks. By adjusting the gate location, you can help to ensure that the material flows evenly throughout the mold cavity.
5, Use the Right Material
Finally, it’s important to choose the right material for your injection molding project. Different materials have different shrinkage rates, which can affect the likelihood of sink marks. By choosing a material with a lower shrinkage rate, you can reduce the chances of sink marks occurring.
In conclusion, sink marks can be a serious problem in injection molding, affecting the appearance and functionality of the final product. However, by following these tips, you can help to avoid sink marks and produce high-quality, defect-free plastic parts.
If you are looking for a reliable and experienced injection mold manufacturer, look no further than JS Precision Company. With our commitment to quality, precision, and fast delivery, we are the perfect partner for all your injection molding needs. Contact us today to learn more about our services and how we can help you achieve your goals.