Custom Injection Molding
The advantage of custom injection molding is that it can produce desired products more flexibly. The use of injection molding technology for production will combine aesthetics with precision, resulting in higher levels of plastic manufacturing services.
Mould Manufacturing Company
The modern mould manufacturing company has a scientific quality management system and advanced manufacturing equipment, rich mold practical experience, and a professional design and development team. Can gradually build a mature injection molding mold manufacturing production line. Manufacturers will research, design, and manufacture high-precision, long-life, and high-performance molds according to customer requirements, providing high-quality custom injection molding services.
Changes in Plastic during the Moulding Process
Mould manufacturing company not only produces molds, but also pay attention to the changes in plastic raw materials in molds and injection molding machines, which can timely change and adjust production methods, and improve production efficiency. During the injection molding process, plastic changes such as softening and melting, flow, shaping, cooling, and solidification.
Softening and Melting
There is a heating device on the outside of the barrel of the injection molding machine, which rotates with the screw. Plastic powder or particles continuously melt as they move forward and are injected into the mold after reaching the nozzle. In addition, the softening and melting of solid plastic particles and powders in injection molding machines mainly rely on sufficient heat provided by the electric heater, which can melt them into a flowing liquid after reaching the melting point. Softening and melting is not only the beginning but also the most crucial step in the molding process, which can ensure that the plastic is injected into the mold in liquid form.
Flow
The fluidity of plastic is related to its density. Plastic materials consist of many molecular structural chains, and the distance between these molecules can affect the fluidity of the plastic. Generally speaking, the tighter the molecular structure, i.e. the higher the density, the more difficult it is for molecules to move and change, and the weaker the fluidity of plastics. Plastic in the molten state flows slower on both sides of the mold cavity, while it has a faster flow velocity in the center of the mold cavity. The molecules of plastic are stretched longitudinally or laterally in the center of the fast-flowing mold cavity. However, due to the effect of shrinkage rate, there is a possibility of warping deformation when liquid plastics undergo cooling and solidification under the action of the cooling system.
Shaping
When liquid plastic in a molten state is injected, it is injected into the mold by a nozzle, and the mold cavity gives the plastic its shape. Under the action of the cooling and exhaust systems, it solidifies to form a molded part. However, due to the relatively short process of spraying and forming, it is also difficult for manufacturers to observe this process. After being molded in the mold cavity, molten plastic enters the curing stage, and the shrinkage problem generated during the curing process is worth paying close attention to.
The Process of Mould Manufacturing
In the process of mould manufacturing, the company needs to pay special attention to the manufacturing process, which can often become the design points of mold manufacturing.
Screw Back Pressure Adjustment: During plastic processing, molten plastic is continuously pushed towards the front end of the barrel by the screw, causing more and more plastic to accumulate and form a backward force, causing the screw to gradually retreat. The manufacturer and mould manufacturing company needs to ensure that the molten plastic can be compacted without residual air and that the screw cannot retreat too quickly. Therefore, a reverse pressure is needed to stop the screw, which is called back pressure. Back pressure can accelerate plasticization, so it is also known as plasticization pressure. It can be controlled by adjusting the return throttle valve of the injection cylinder. During the injection molding process, adjusting the appropriate back pressure based on specific circumstances can make the melt inside the barrel more compacted, increase the density between plastics, reduce the defect and scrap rate of molded parts, extrude gas inside the melt, reduce surface bubbles and internal bubbles, and improve the surface glossiness of the product; Being able to slow down the screw’s backward speed allows more time for the melt in the barrel to plasticize, avoiding defects caused by uneven color powder and air ingress; Properly increasing back pressure can also improve the shrinkage rate of plastic parts, enhance the quality of plasticization, and enhance popularity.
Temperature Control of the Material Barrel: In the injection molding process, the temperature of the material barrel is closely related to the temperature of the solution, but the temperature of the material barrel is often lower than that of the melt, which is influenced by the plastic properties and injection speed. The melt temperature must be controlled within an appropriate range. If the temperature is too low, the plasticization process will be affected, thereby affecting the overall quality of the workpiece and increasing the manufacturing steps; If the temperature is too high, it is easy to cause the raw materials to decompose. The temperature of the barrel often affects the injection pressure. The suitable barrel temperature for each type of plastic raw material varies and needs to be determined based on the characteristics and basic principles of the plastic. When searching for and determining its optimal temperature, only a small adjustment is needed each time. For polymers with weaker atomic groups, the optimal injection temperature is about 50 degrees higher than the melting point, and considering its optimal injection temperature requires significant adjustment.
Mold Temperature Setting: The correct adjustment of mold temperature by the manufacturer can ensure the quality of the mold and parts. For example, ABS products often have high requirements for appearance and quality. The temperature on the inner and outer sides of the product surface in the mold cavity can be set at around 50-65 ℃, while the temperature on the inner side should be set about 10 degrees higher than the outer side. At this time, the shrinkage rate of the product is small and the aesthetics are high. If the mould manufacturing company logo and product parameters are printed on the surface of the product, a higher mold temperature can be used to make it clearer. For crystalline plastics, the crystallization rate is controlled by the cooling rate. If the mold temperature is increased, it will increase the cooling time, increase the crystallinity of the plastic, and improve the dimensional accuracy and performance of its products. For example, crystalline plastics such as nylon plastic, polymethyl methacrylate, PBT plastic, etc. can adopt the higher mold temperature mentioned above.
Control of Injection Volume: Generally, the injection volume set by the mould manufacturing company should be 85% of the factory-set injection volume of the injection molding machine. But in actual production, if the injection amount set is too small, the plastic will remain in the barrel for a long time, leading to decomposition. To avoid this phenomenon, the actual injection volume should be more than 30% of the factory-set injection volume of the injection molding machine. Therefore, it is best to set the injection volume in normal use between 30% and 85% of the injection volume set by the injection molding machine at the factory.
Maintenance of Molds by Mould Manufacturing Company
In general, mould manufacturing company pays attention to the maintenance and upkeep of molds, whether during use or temporary storage, to maintain their accuracy and extend their service life.
The mould manufacturing company needs to focus on monitoring and inspecting several important components. The ejection and guiding components can ensure that the mold can open and close normally and the plastic part can be ejected normally. If one of the parts is damaged, it will cause the mold to fail to operate normally, resulting in production stoppage and reduced efficiency. Therefore, daily inspection and maintenance of the guide pin and other components are necessary. If damage occurs, maintenance or replacement should be carried out to ensure continued operation. When completing a certain cycle of work and moving on to the next cycle of production, it is necessary to lubricate or prevent rust on the mold and its various components, especially in areas with severe wear and tear (such as gears, bearings, etc.), to ensure that they are always at their best performance; After a long production cycle of the mold, it is easy to deposit scale, rust, silt, and algae in the cooling channel, causing blockage and narrowing of the cooling channel, reducing the cooling rate. Therefore, the channel should be cleaned regularly.
Manufacturers and enterprises should first provide detailed record cards for each set of molds, to accurately record and count their usage, maintenance (lubrication, cleaning, rust prevention), and repair status. Based on the record cards, the usage time and repair records of the molds can be found to determine which components need to be replaced. Detailed information about each set of molds, such as parameters, production date, manufacturing materials, etc., can also be provided.
It is important to pay attention to the daily surface maintenance of molds, with a focus on preventing them from becoming rusted and rough, which directly affects the surface quality of products. Therefore, it is particularly important to choose a suitable anti-rust oil. When the mold needs to be put to the next use after completing the production task, corresponding methods should be taken carefully according to different injection molding processes to remove residual injection molding. Copper rods, copper wires, and professional mold cleaning agents can be used to remove residual injection molding and other deposits inside the mold, and then placed in a dry environment to air dry. If a hard substance is used for cleaning, it can cause scratches on the surface of the mold, thereby affecting the quality of the mold. If a mold is corroded and rusted, it can be polished, rust removed, and polished using a grinder or other equipment. Finally, rust inhibitors can be added and stored in a dry and ventilated place.
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