The quality of the automation machine equipment shell has a vital impact on the overall performance, appearance and service life of the equipment, and the precision injection molding process is the key link to ensure the quality of the shell. The following are its key control points.
First, mold design and manufacturing are the basis. The precision of the mold directly determines the dimensional accuracy and shape accuracy of the shell. In the design stage, the structural characteristics of the shell, such as the uniformity of wall thickness and the distribution of reinforcing ribs, should be fully considered to avoid local over-thickness or over-thinness leading to injection defects. For example, for shells with complex curved surfaces or undercut structures, a special demolding mechanism design is required to ensure smooth demolding without damaging the product. At the same time, the manufacturing accuracy of the mold should be controlled within a very small range, and the general dimensional tolerance should be within ±0.05 mm. Through high-precision processing equipment and strict testing methods, such as three-coordinate measuring machines, the processing quality of key parts such as mold cavities and cores is guaranteed to provide precise molding space for precision injection molding.
Secondly, the selection and processing of raw materials cannot be ignored. Appropriate plastic raw materials should be selected according to the performance requirements of the shell, such as strength, toughness, heat resistance and other requirements. Before injection molding, the raw materials must be fully dried to remove moisture, because too high a moisture content will cause defects such as bubbles and silver wires during the injection molding process, affecting the appearance and mechanical properties of the shell. For example, for some engineering plastics that are sensitive to moisture, such as nylon, the drying temperature is usually controlled at 80-100℃ and the drying time is 4-6 hours to reduce the moisture content to below 0.1%, thereby ensuring the stability of injection molding and product quality.
Furthermore, precise control of injection molding process parameters is the core. Parameters such as injection pressure, speed, temperature, and holding time are interrelated and have a decisive effect on the injection molding effect. Excessive injection pressure may cause mold deformation or flash, while too low injection pressure may result in insufficient filling; too fast injection speed is prone to cavitation, while too slow injection speed will cause the melt to cool prematurely. For example, when injecting a large automation machine equipment shell, the injection pressure is generally controlled at 80-120MPa, the injection speed is adjusted between 20-50mm/s according to the product structure and wall thickness, the barrel temperature is set in a suitable range according to different plastic raw materials, such as the polypropylene barrel temperature is 180-220℃, and the product is fully molded and dimensionally stable through a reasonable holding time, which is usually between 10-30 seconds. By continuously optimizing the combination of these parameters, high-quality shell products can be obtained.
Finally, quality monitoring and post-processing during the injection molding process are also extremely important. During the injection molding process, advanced monitoring equipment, such as online dimension measuring instruments and defect detection systems, should be used to monitor the size and appearance defects of the product in real time, and adjust the process parameters in time once problems are found. The shell after injection molding may have residual stress, and appropriate post-processing is required, such as annealing, keeping it warm at a certain temperature for a period of time, eliminating stress, improving product dimensional stability and mechanical properties, and ensuring that the automation machine equipment shell can meet the high-precision and high-reliability requirements of the equipment.
