Injection molding is an efficient, precise, and stable plastic processing technology that has become an indispensable part of modern industrial manufacturing. With the continuous development and progress of technology, injection molding technology will continue to innovate and improve, bringing more possibilities for the production of plastic products.

The manufacturing accuracy of molds is the key to ensuring the dimensional accuracy of plastic products. In the process of mold manufacturing, it is necessary to strictly control the dimensional tolerances, geometric tolerances, etc. of the mold cavity. The adjustment of injection molding process parameters can also affect the dimensional accuracy of plastic products. Changes in parameters such as injection pressure, holding pressure, and cooling time can affect the shrinkage rate of plastic products, thereby affecting dimensional accuracy.

What are the effects of mold temperature on the surface quality of plastic products during injection molding in Dalian

1、 Glossiness

The influence of high-temperature molds: When the mold temperature is high, the cooling rate of plastic melt in the mold cavity is relatively slow. This allows more time for plastic molecules to arrange in an orderly manner, resulting in a smoother and more glossy surface of plastic products. For example, in the production of plastic products with high appearance requirements, such as automotive interior parts, high-end electronic product casings, etc., higher mold temperatures are usually used to achieve good glossiness. For example, for electronic product casings made of polycarbonate (PC) material, setting the mold temperature at around 80-100 ℃ can result in a high gloss effect on the surface of the product.

The impact of low-temperature molds: On the contrary, if the mold temperature is low, the cooling rate of the plastic melt is accelerated, and the molecules cannot be arranged in an orderly manner in time. The surface of the plastic product may appear rough and the glossiness may decrease. In some cases where glossiness is not high or to achieve a special matte effect, lower mold temperatures can be used. For example, some industrial plastic products can choose lower mold temperatures to achieve a matte surface in order to reduce reflection and avoid glaring gloss.

2、 Weld mark

The function of high-temperature molds: Higher mold temperatures help reduce the occurrence of weld lines. During the injection molding process, when the plastic melt enters the mold cavity from different gates or channels, fusion marks will form at the intersection. Raising the mold temperature can make the fusion of plastic melt at the intersection more complete and reduce the degree of weld marks. For example, in the production of large plastic products, multiple gates may be required for filling. By increasing the mold temperature, the problem of weld lines can be effectively improved and the surface quality of the product can be enhanced.

The influence of low-temperature molds: Lower mold temperatures will slow down the fusion speed of plastic melt at the intersection, and the weld lines will be more obvious. This is because the fluidity of plastic melt deteriorates at low temperatures, making it difficult for different parts of the melt to fully bond during fusion, resulting in more prominent weld lines.

3、 Flow mark

The impact of high-temperature molds: Higher mold temperatures can reduce the generation of flow marks. When the mold temperature is high, the flowability of the plastic melt in the cavity is better, which can fill the cavity more evenly and reduce the flow marks caused by unstable melt flow. For example, when injecting some thin-walled plastic products, increasing the mold temperature can effectively avoid the occurrence of flow marks and make the surface of the product smoother.

The impact of low-temperature molds: Low temperature molds can reduce the fluidity of plastic melt, which can easily lead to uneven flow of the melt during the filling process of the mold cavity, resulting in flow marks. Especially in the case of uneven mold temperature, the problem of flow marks will be more severe. For example, if the temperature of certain parts of the mold is low, the flow velocity of the melt in these parts will slow down, which will be inconsistent with the flow velocity of the melt in other parts, and flow marks will be formed on the surface of the product.

4、 Shrinkage mark

The function of high-temperature molds: Increasing the mold temperature appropriately can reduce the occurrence of shrinkage marks. A higher mold temperature causes more uniform shrinkage of the plastic melt during the cooling process, thereby reducing the degree of shrinkage marks. For example, when injecting thick walled plastic products, increasing the mold temperature can reduce shrinkage marks caused by uneven cooling.

The impact of low-temperature molds: Lower mold temperatures can cause rapid cooling of the plastic melt in the mold cavity, resulting in uneven shrinkage and easy formation of shrinkage marks on the surface of the product. Especially in the thick walled parts or reinforced structures of plastic products, due to the fast cooling rate and significant shrinkage differences, the problem of shrinkage marks will be more pronounced.

5、 Surface roughness

The impact of high-temperature molds: High temperature molds help reduce the surface roughness of plastic products. At higher mold temperatures, plastic melt can better replicate the details of the mold cavity surface, making the product surface smoother and more delicate. For example, for some precision plastic products, using high-temperature molds can improve surface quality and meet high-precision requirements.

The impact of low-temperature molds: Low temperature molds can increase the surface roughness of plastic products. Due to the fast cooling rate, the plastic melt may not be able to fully fill the fine parts of the mold cavity, resulting in rough textures on the surface of the product. In addition, the arrangement of plastic molecules at low temperatures is not tight enough, which further affects the smoothness of the surface.

Injection molding has the advantages of high production efficiency, low cost, and stable product quality. Today, injection molding has become one of the mainstream processes for plastic product processing. In industrial manufacturing, injection molding is widely used in the production of automotive parts, mobile phone casings, household appliance parts, and other products. Compared with traditional plastic product processing methods, injection molding can produce plastic products with complex structures and more stable product quality.

With the development of industrial automation technology, injection molding will increasingly trend towards intelligent production. By adopting advanced sensor technology, control systems, and robot technology, automation control, online detection, and fault diagnosis of the injection molding process can be achieved, improving production efficiency and product quality.