Plastic material proportioning

In addition to polymers, various plastic additives (such as stabilizers, plasticizers, colorants, lubricants, reinforcers and fillers) are generally added to the raw materials used in plastic processing to improve the molding process and the performance of products or reduce the cost of products. The additive and polymer are mixed and evenly dispersed into powder, also known as dry mixture. Sometimes the powder needs to be processed into granules by plastic refining. This kind of powder and granule is called batch or molding compound.

Plastic molding

The key link of plastic processing. Various forms of plastics (powder, granule, solution or dispersion) are made into products or billets of the required shape. There are more than 30 molding methods. Its choice mainly depends on the type of plastic (thermoplastic or thermosetting), the initial shape and the shape and size of the product. The common processing methods of thermoplastic include extrusion, injection molding, calendering, blow molding and thermoforming. The processing methods of thermosetting plastics include molding, transfer molding and injection molding. Lamination, molding and thermoforming are used to make plastics form on a flat surface. The plastic processing method can be used for rubber processing. In addition, there are liquid monomer or polymer as raw material casting. Among these methods, extrusion and injection molding are the most popular and the most basic.

Plastic joint

The methods of joining plastic parts are welding and bonding. Welding methods include hot air welding with welding rod, hot melt welding with hot electrode, high frequency welding, friction welding, induction welding, ultrasonic welding, etc. Bonding method can be divided into flux, resin solution and hot melt adhesive according to the adhesive used.

Plastic parts assembly

By means of bonding, welding and mechanical connection, the finished plastic parts are assembled into complete products. For example: plastic profiles, through sawing, welding, drilling and other steps to assemble into plastic window frames and plastic doors.

machining

By using metal and wood processing methods, we can manufacture plastic products with very accurate size or a small quantity, and can also be used as an auxiliary molding process, such as sawing of extruded profiles. Because the performance of plastics is different from that of metal and wood, the thermal conductivity of plastics is poor, the coefficient of thermal expansion and elastic modulus are low. When the clamp or cutter is pressurized too much, it is easy to cause deformation, and it is easy to melt when heated during cutting, and it is easy to adhere to the cutter. Therefore, when machining plastics, the cutting tools used and the corresponding cutting speed should adapt to the characteristics of plastics. Commonly used machining methods include sawing, shearing, punching, turning, planing, drilling, grinding, polishing, thread processing, etc. In addition, plastic can also be cut off, drilled and welded by laser.

Surface modification

The purpose is to beautify the surface of plastic products, which usually includes: mechanical modification, such as file, grinding, polishing and other processes to remove the burr and burr on the parts, and to correct the size; finishing, including coating the surface of the parts with paint, brightening the surface with solvent, and coating the surface of the products with patterned film; coloring, including color drawing, printing and hot stamping; metal plating, including vacuum coating Electroplating and chemical silver plating. Hot stamping is to transfer the color aluminum foil layer (or other pattern film layer) on the hot stamping film to the product under heating and pressure. Many household appliances, building products and daily necessities use this method to obtain metal luster or wood grain patterns.