Green Vitality Industry Co., Ltd.
Green Vitality Industry Co., Ltd.

Injection mold hot runner and cold runner

Cold runner: refers to the part between the mold gate and the product gate. The plastic stays in the runner by injection pressure and its own heat. The runner is a part of the molded material, but it does not belong to the product. Therefore, when we design injection molds, we should consider both the filling effect and how to save material by shortening or reducing the runner size. Ideally, this is achievable, but it is difficult to achieve in practical applications.

Hot runner: a commonly used component of the injection mold system, which uses heating to ensure that the plastic in the runner and gate stays melted. Because heating rods and heating rings are located near or at the center of the runner, the entire runner from the injection machine nozzle to the gate is in a high-temperature state, which keeps the plastic in the runner molten. After the shutdown, the solidified material does not need to be removed by opening the runner, and when restarting, the runner needs to be heated to the required temperature. Therefore, the hot runner process is sometimes called a hot manifold system, or referred to as a no-runner mold.

The surface treatment process of injection molds

Sand blasting, texture and spark patterns are all within the range of mold surface treatment. Of these three surface treatment techniques, sand blasting and texture are more commonly used, while spark patterns are less common. For the three processes of sandblasting, texture, and spark patterns for plastic molds, here is a summary explanation.

Sand blasting refers to shooting quartz sand at the mold surface using an air gun with a certain pressure, thus forming a sandblasted surface layer on the plastic mold surface. When the plastic mold injects the product, a sandblasting effect will be formed on the product surface. Sand blasting is generally divided into fine sand and coarse sand. For sandblasting treatment, the surface of the plastic part is easily worn.

Texture is made by chemical corrosion using chemical solutions. There are the most types of texture surfaces, which can imitate various effects. The price of texture processing varies greatly, and the technology of texture process has a high level of technical competence. The prices of different textures are relatively low. However, for three-dimensional textures used in automobile interior and household appliance molds, the price will be much higher.

Spark patterns refer to the patterns left on the product surface after the electrospark machining of plastic molds. Often, the product surface is left with spark patterns after the mold is electrically discharged, which is accepted as the spark pattern treatment. Generally, spark patterns are not intentionally processed by electrode processing because it raises costs.

For the surface treatment technology of injection molds, texture is the most commonly used. Of course, the actual product needs to adopt which surface treatment still depends on the purpose of the plastic part.

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