Structural factors and related knowledge to be considered in plastic mold design
Date: October 21, 2024
Structural factors and related knowledge to be considered in plastic mold design
Plastic mold design is based on correct plastic product design, and mold design and manufacturing are closely related to plastic processing. The success or failure of plastic processing largely depends on the design effect and manufacturing quality of the mold. The structural elements that need to be considered in plastic mold design include:
1. The parting surface refers to the contact surface where the concave and convex molds cooperate with each other when the mold is closed. The selection of its position and form is influenced by factors such as the shape and appearance of the product, wall thickness, molding method, post-processing technology, mold type and structure, demolding method, and molding machine structure.
2. Structural components, including sliders, inclined tops, and straight top blocks of complex molds. The design of structural components is crucial, as it relates to the lifespan, processing cycle, cost, and product quality of the mold. Therefore, designing complex core structures for molds requires a high level of comprehensive ability from designers, who strive for simpler, more durable, and more economical design solutions as much as possible.
Mold structure design
The size of the plastic parts is small, the precision level of the products is low, and good performance, no cracks, bending resistance, and large-scale production are required. The mold is designed as the first mock examination with eight cavities, and the following problems are solved.
1、 The balance problem of the pouring system in multi cavity molds is designed to ensure that all cavities are fed at the same time as much as possible. Due to the increase in the number of cavities, the length of the distribution channel will inevitably increase. Before the molten material reaches the cavity, there will be significant losses in injection pressure and heat. If the distribution channel design is slightly unreasonable, defects may occur in the plastic part, such as insufficient injection in one or several cavities, or immediate filling, but there are defects such as poor fusion or loose internal structure. If the injection pressure is increased, it is easy to produce burrs. The design of the diversion channel in the paper adopts a non-equilibrium arrangement. By setting the size of the sprue and diversion channel, the injection process is adjusted to a certain value to ensure consistent shrinkage rate of each cavity. For the plastic parts with the highest precision requirements, interchangeability is guaranteed. The sprue is located at the thick end of the plastic part marked as the Y end, which is conducive to flow and shrinkage, and can also avoid the formation of weld marks. The molecules have directionality to meet the requirements of bending without fracture.
2、 The design principle of the cooling system for this cooling device is to design the cooling device on the basis of not increasing the structure of the mold itself. On the premise of meeting the required transmission area for cooling and allowing the mold structure, the number of cooling circuits should be designed as much as possible, and the diameter of the cooling channel should be as large as possible. Cooling water holes should be machined on the upper and lower cavity plates and the dynamic fixed template. During installation, the cooling water holes on the upper cavity plate should be connected to the water holes on the fixed template, and then sealed with a sealing ring. The cooling water holes on the lower cavity plate should be connected to the water holes on the dynamic template, and also sealed with a sealing ring. The water holes should be arranged on the upper and lower cavity plates and the dynamic fixed template.