The first key point of the design of plastic products processing molds is to conduct a comprehensive and in-depth analysis of the products, which is the basis of design. Product analysis needs to focus on factors such as product dimensional accuracy, surface quality, geometric shape, and usage functions. Taking the mobile phone shell as an example, its dimensional accuracy requirements are extremely high, the matching tolerances of each component must be accurate to the millimeter level, and the surface must be smooth and flawless; at the same time, the functionality of buttons, interfaces and other parts must be considered. Only by accurately grasping the product requirements can we determine the design schemes such as the parting surface, demoulding method, and pouring system of the mold, and provide direction guidance for subsequent design.
The selection of mold materials plays a decisive role in the performance and service life of the mold, and is an important part of mold design. The selection of mold materials needs to comprehensively consider factors such as the production batch, plastic material characteristics, and molding process conditions of plastic products processing. For mass-produced molds, steels with high strength, good wear resistance, and excellent heat treatment performance are often used, such as Cr12MoV; if small precision products are produced, mold steels with high hardness and good polishing performance can be used to ensure the surface quality of the product. In addition, the cost and processing performance of the material must also be considered to maximize cost-effectiveness while meeting the use requirements.
The structural design of the mold is the core to ensure the normal operation of the mold and realize the molding of plastic products processing, covering many aspects. The structural design includes parting surface design, cavity and core design, pouring system design, demoulding mechanism design, etc. The selection of parting surface should facilitate the demoulding and mold processing of the product, while ensuring the appearance quality of the product; the pouring system design needs to reasonably plan the size and shape of the main channel, branch channel and gate to ensure that the plastic melt fills the cavity evenly and quickly; the demoulding mechanism must ensure that the product can be smoothly ejected from the mold without damaging the product. Reasonable structural design can improve the working efficiency and reliability of the mold and reduce the failure rate in the production process.
The pouring system is the channel for the plastic melt to enter the mold cavity, and its design directly affects the molding quality and production efficiency of plastic products processing. The pouring system design must follow the principles of melt flow balance, small pressure loss, and easy removal after molding. According to the shape, size and characteristics of the product and the plastic, determine the type of gate (such as side gate, point gate, latent gate, etc.) and position, as well as the cross-sectional shape and size of the runner. For example, for thin-walled products, point gates can be used to increase the shear rate of the melt, reduce the melt viscosity, and facilitate filling; at the same time, reasonable flow channel design can reduce the heat and pressure loss of the melt during the flow process, and ensure the molding accuracy of the product.
In the molding process of plastic products processing, temperature control is crucial, and the design of cooling and heating systems is indispensable. The function of the cooling and heating system is to adjust the mold temperature so that the plastic melt can be quickly cooled and solidified or evenly heated and plasticized. The cooling system usually uses circulating water cooling. By opening cooling water channels in the mold and reasonably arranging the position, number and shape of the water channels, the temperature of each part of the mold is ensured to be uniform, the molding cycle is shortened, and the production efficiency is improved; for some special plastics or complex products, a heating system, such as electric heating rods, heating plates, etc., may be required to ensure the fluidity of the plastic melt and the molding quality of the product.
The accuracy of the mold is directly related to the dimensional accuracy and quality stability of plastic products processing. Accuracy control is one of the key points of mold design. Accuracy control involves the processing accuracy of mold parts, assembly accuracy, and wear compensation of molds. In the process of mold parts processing, high-precision processing equipment and advanced processing technology should be used to strictly control the dimensional tolerance and form and position tolerance of parts; in the assembly process, the matching accuracy of each component should be guaranteed to avoid the situation where the gap is too large or too small. In addition, the wear factor of the mold during use should be considered, and a certain wear margin should be reserved. Through regular maintenance and mold repair, the mold accuracy should always meet the production requirements.
In the process of mold design, cost optimization is also a key point that cannot be ignored. Cost optimization needs to be comprehensively considered from multiple aspects such as material cost, processing cost, and maintenance cost. In terms of material selection, on the premise of meeting the performance requirements of the mold, reasonably priced materials should be selected; in terms of processing technology, efficient and economical processing methods should be adopted, and the processing procedures should be reasonably arranged to reduce processing costs; at the same time, a reasonable mold structure should be designed to facilitate the installation, commissioning and maintenance of the mold and reduce maintenance costs. Through cost optimization, the quality and performance of the mold can be guaranteed, the cost performance of the mold can be improved, and the market competitiveness of the enterprise can be enhanced.
