These defects in injection mold parts are not caused by equipment failure, but by injection molders who do not understand what changes in performance during the injection molding process. Understanding what causes a finished part to not survive the intended environment in which it was designed to operate is critical.

    Cavity pressure

    Cavity pressure is directly related to part size. Changes in cavity pressure will change the dimensions of the part. The smaller the change, the tighter the dimensional control or change. The higher the cavity pressure value, the less the part shrinks, and all other values ​​are held constant. One shrinkage rule to keep in mind is that the plastic shrinks less in the direction of the plastic flow and more in the direction perpendicular to the flow. A common mistake in this process is when molders try machine settings to determine when the gate freezes. At this point, a defect appears in the part and then moves in reverse until the defect disappears. The problem with this is that the other 3 processes will interfere with the performance of the finished part in ways that the molder cannot see.

    Cooling and injection rate

    The speed at which plastic is injected into the mold, combined with cavity pressure, cooling rate, and melt temperature, will determine the amount of stress the plastic is subjected to before the finished plastic part begins to show signs of cracking and/or warping.

    Improper melt temperature

    A final common processing defect is improper melt temperature. You will see the recommended temperature range when using the processing guidelines provided by the material manufacturer. This process value is important to ensure that you do not destroy any of the chemicals involved in making the final part. Mold temperature is equally important for stress generation. Before attempting to mold the first part, make sure that the resin exits the nozzle in a uniform, smooth, creamy melt to ensure the full amount of resin that will be injected into the mold.

    Taizhou Huangyan Jinhong Plastic Mould Parts Co., Ltd. is an injection mold maker from China Ejector sleeve, its own plastic mold factory specializes in the production of plastic compression springs, positioning components, and other products.