Briefly describe the knowledge points of plastic products processing and production
Plastic products are a general term for daily life and industrial products processed from plastic as the main raw material, including all processes of plastic injection molding, blister and other products. Plastic is a kind of plastic synthetic polymer material. It forms three indispensable synthetic materials in daily life with synthetic rubber and synthetic fiber. Specifically, plastic is a material that is mainly composed of natural or synthetic resin, and various additives are added. Under certain conditions of temperature and pressure, it can be formed into a certain shape, and the shape remains unchanged at room temperature.
The production of plastic products generally includes plastic ingredients, molding, processing, connection, decoration and assembly. The four processes are carried out after the plastic is formed into a product or semi-finished product, also known as plastic secondary processing.
The key link in the processing of plastic products: various forms of plastic are made into products or blanks of the desired shape. There are more than 30 molding methods. Its selection depends primarily on the type of plastic (thermoplastic or thermoset), the initial shape, and the shape and size of the product. Common methods of processing thermoplastics from plastics include extrusion, injection molding, calendering, blow molding, and thermoforming, among others. Thermosets are typically processed by compression molding, transfer molding, and injection molding. Lamination, molding, and thermoforming are used to shape plastic on a flat surface. The above plastic processing methods can be used for rubber processing. In addition, there are castings that use liquid monomers or polymers as raw materials. Among these methods, extrusion and injection molding are the most used and basic molding methods.
Mechanical processing of plastic products production: plastic products with precise dimensions or a small number of plastic products can be manufactured by metal, wood and other plastic processing methods, and can also be used as an auxiliary process for forming, such as sawing and extruding profiles. Since plastics behave differently from metals and woods, they have poor thermal conductivity, a low coefficient of thermal expansion, and a low modulus of elasticity. When the clamp or tool is under too much pressure, it is easy to cause deformation, melt and stick to the tool when heated. Therefore, when processing plastics, the tools used and the corresponding cutting speeds should be adapted to the characteristics of the plastic. Commonly used processing methods include sawing, shearing, punching, turning, planing, drilling, grinding, polishing, threading, etc. In addition, plastics can be laser cut, stamped and welded.
Connection in the production of plastic products: The connection methods of plastic parts in plastic processing include welding and bonding. Welding methods include electrode hot air welding, electrode hot melt welding, high frequency welding, friction welding, induction welding and ultrasonic welding. The bonding method can be divided into flux, resin solution and hot melt adhesive according to the different adhesives used.
Surface modification in the production of plastic products: The purpose is to beautify the surface of plastic products, which usually includes: mechanical modification, that is, the use of filing, grinding, polishing and other processes to remove burrs and burrs on parts, and to correct the size; finishing, including using Paint the surface of the product, brighten the surface with a solvent, coat the surface of the product with a patterned film, etc.
Production and assembly of plastic products: The operation of assembling manufactured plastic parts into complete products by means of bonding, welding, mechanical connection, etc. For example, plastic profiles are assembled into plastic window frames and plastic doors by sawing, welding, drilling and other steps.