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With the rapid development and progress of the industry, product diversity and demand for output are increasing, and various plastic products with large plasticity and low prices have emerged accordingly. The injection method of mold has become one of the best methods for mass productions. Most of the early plastic mold manufacturing methods were made based on the experience of mold masters. If the plastic injection machine is poorly filled during the mold trial period, the mold feed runner system needs to be modified. There are many problems caused the mold cannot proceed smoothly to eject the products. With the increasing requirements for the quality and dimensional precision of plastic products and the shortening of the development time for plastic molds, the use of computer-aided mold flow analysis before manufacturing plastic molds has become relevant to the development and design of plastic products. This is an unavoidable trend in the industry.
In this thesis, we designed the soap dish with x-rib direction and the y-rib direction, and designed the circular, trapezoidal, and semicircular runners in the plastic mold with the single-cavity and two-cavity. Shaped gates are 0.8x2.5, 1.0x2.5, 1.25x2.5, and 1.50x2.5 mm. According to mold flow analysis under the conditions of filling time, injection pressure, pressure drop, and average temperature settings to find out the data of the best feeding method is used as a reference and choice for the design and manufacture of plastic molds. The filling result of the plastic injection will be affected by the structure of the plastic product, the shape and size of the plastic feed channels and gates, and the setting of the plastic injection conditions. The results of this study show that the x-rib direction is better than the y-rib direction. This is because the design of the x-rib and the x-rectangular product have the same direction, so the plastic flow resistance is smaller and the filling time is shorter, and the injection pressure is smaller. Compared with the pressure drop and the lower average temperature, the mold flow benefit is excellent. The designed y-rib and x rectangular products are in the opposite direction, which makes the plastic flow resistance larger and has a longer filling time, larger injection pressure and pressure drop, and higher average temperature, so mold flow efficiency is relatively poor. In addition, the data of the short runner is better than the long runner; the trapezoidal runner is better than the circular runner; the circular runner is better than the semicircular runner. Although the filling time of the semicircular runner is the fastest, the data of injection pressure, pressure drop, and average temperature are relatively high, indicating that the semicircular runner is detrimental to the life of the plastic mold and the quality of plastic products. In order to prevent the flow mark of the plastic product caused by too fast injection speed, depending on the condition of the plastic product in the design of the plastic mold, the runner is sometimes designed as a turning form to increase the plastic flow time and improve the injection speed.
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