Plastic Injection Molding
Plastic injection molding is a method in which plastic is first heated and melted in the heating cylinder of an injection molding machine, and then pushed into the mold cavity of a closed mold by a reciprocating screw to form. It can not only produce high-precision and high-quality products with high productivity, but also has a wide variety of plastic varieties that can be processed, with large output and wide applications. It is one of the important molding methods in plastic processing.
Plastic Forming Company | Advantages ＆ Equipment
The most important tools for a plastic molding company are injection molding machines and equipment, and the manufacturer combines the two widely used in the plastic injection molding industry. The so-called injection molding is the process of heating and melting granular or powdered plastic raw materials, and then pushing them through high-speed and high-pressure injection machine screws. They are then injected into the closed mold cavity through the nozzle at the front end of the barrel, cooled, and solidified to form an injection molded part. Finally, the mold is opened and the product is taken out.
The Advantages of Injection Molding
The reason why plastic molding company chooses injection molding technology for production is because it has immeasurable advantages and advanced operating methods. The outstanding advantages include but are not limited to:
- High Degree of Automation
Compared to other plastic molding methods, plastic injection molding has a higher degree of automation, resulting in faster production speed. The molds inside the injection molding machine can be injected into multiple sets at the same time, producing more products per minute. Therefore, injection molding can support the production of large quantities of plastic molded parts, meeting the production requirements of high-quantity products.
- Good Surface Quality
The plastic surface formed by plastic injection molding has high quality and good smoothness. Under the high-precision and high-pressure processing of injection molding, the finished product can achieve excellent surface smoothness and fewer defects, which enables the molded parts to have a good appearance and attract more users.
- High Flexibility
Plastic injection molding has high flexibility, and products of various shapes and sizes can be produced with high quality. By using different molds, various products of different sizes and appearances can be produced. This performance expands the application range of plastic products, such as automobiles, electronics, medical, and other fields.
- Rich Product Aappearance
Plastic injection molding can achieve product design with various appearances. According to the customer’s requirements for producing products, a plastic injection molding company can design more exquisite and complex geometric structures, details, and curves on the mold. This more flexible design allows the product to meet more production needs and makes greater progress in appearance and functionality.
- High Cost-effectiveness
Compared to other plastic molding technologies, plastic injection molding can achieve higher quality products with less budget. Mainly because the manufacturing of plastic molding molds is relatively simple and the time used is relatively short, on the other hand, the selection of plastic raw materials is also relatively wide.
Electrical and Hydraulic Systems for Injection Molding
The power source of the injection molding machine used by a plastic molding company is the electrical part, and the most important parameter of the electrical part is temperature. The hydraulic system operates under the control of the electrical system and is also the main power source of the injection molding machine.
The electrical part of the injection molding machine is the power source for the action of the injection molding machine, which includes the power supply for the oil pump motor, electric heating power supply, driving circuit, and control circuit. The heating power supply is divided into a heating main circuit and a control circuit, mainly controlling the temperature parameters of injection molding. The heating circuit heats the glue cylinder and converts electrical energy into thermal energy through the heating ring. The function of the control circuit is to collect temperature signals for the heating circuit and transmit electrical energy.
The temperature process parameters set by the electrical system directly determine the quality of injection molded products. Many factors affect temperature process parameters, such as the plastic raw materials used in processing, the heating temperature of the machine’s glue cylinder, and the injection temperature and mold temperature. There are various types of plastics, and their properties vary, such as density, water absorption, and melting point. If recycled raw materials and other additives are mixed in during processing, the temperature of the set glue cylinder will also need to be changed. If different models of injection molding machines are used, the temperature setting of the glue barrel also needs to be different, so the plastic molding company needs to conduct a specific analysis of the problem. For commonly used plastic raw materials such as PS, PE, PP, PA, POM, ABS, etc., the temperature should be set according to the technical parameters provided by the supplier. For thermosensitive plastics, the temperature setting needs to be stricter, while also considering other factors, such as the frictional heat generated during the plasticization process. Generally, the initial temperature can be set lower and raised during or after debugging to prevent sudden temperature increases that may cause raw material decomposition. If the plastic injection molding company does not take these into account, it can cause product quality or machine damage. For example, manufacturers overlook the temperature control of PVC. Excessive temperature can cause plastic raw materials to decompose or burn, which can also affect production and damage screws and glue cylinders. Not only that, the debugging and setting of temperature parameters also need to start from the actual production and processing, considering the performance of plastic raw materials, the accuracy requirements of mold cavity size, and the pressure generated during the injection molding process.
When the temperature set by the plastic molding company is not appropriate, it will result in:
Low temperature can cause plastic to be unable to be fully heated to a molten state, resulting in poor plasticization. For example, the product may become brittle, the transparency may not meet the requirements, the injection molding may not be sufficient, there may be fusion marks on the plastic product, mica electric delamination and peeling, rough surface, surface flow patterns, and corrugated cold blocks or stiff materials. Low mold temperature can also cause layered defects in the product’s gate.
The hydraulic system of the injection molding machine is the power source for injection molding, which is driven by the electrical control system to drive the mechanical transmission part and convert hydraulic energy into mechanical energy. The core component of the hydraulic transmission system is the power component oil pump, which drives the actuator to move through the control components. The oil motor drives the screw to rotate and plasticize the plastic. The function of the hydraulic system also includes heat dissipation, oil storage, filtration, impurity precipitation, cooling pressure oil, and displaying pressure values. Each part of the hydraulic system is closely related to injection molded products, mechanical transmission, and electrical control. Therefore, the hydraulic transmission system is a crucial component in the injection molding production process. The core component that provides pressure to the hydraulic system is the oil pump, which is also the pressure source of the system and can directly affect the reliable and stable performance of each injection molding action and the quality of the injection molded parts. When conducting product calibration and troubleshooting, it is necessary to ensure that the hydraulic system can operate normally. Therefore, when the cause of product defects cannot be identified, manufacturers can inspect the hydraulic system, which can be said to be the key point of troubleshooting.
The Transmission System of Injection Molding Machines
The injection molding machine used by a plastic injection molding company is mainly composed of a transmission part, which is the execution part of the injection molding machine instructions and usually consists of a passive device and a driving device.
In the transmission system of injection molding equipment, if there is a fit gap between the screw of the injection part and the glue barrel, the template will be unbalanced, resulting in gaps between the dynamic and static templates, causing defects in the injection molded product. Under normal circumstances, plastic raw materials are heated by a heating ring, melted, and plasticized. During injection, the molten material is pushed into the mold cavity through the nozzle. If the gap between the screw and the glue cylinder is too large and severely worn, it cannot be completely plasticized, affecting the quality of the product. If the screw’s gluing meson is damaged, it will cause glue leakage or weak injection, resulting in the inability of the plastic part to form.
An important component of the transmission system is the locking part, whose locking rigid body is mainly composed of a template and a pull rod, supporting the opening and closing actions of the moving mold. The angle between the template and the frame, the parallelism between the pull rods, and the coaxiality between the nozzle and the template pouring port all affect the final quality of the injection molded product. Improper coordination between the mechanical transmission mechanisms of injection molding equipment or insufficient lubricating oil can lead to machine wear and tear; If not calibrated properly, the machine will experience significant vibration or wear, resulting in a significant reduction in the lifespan of the equipment.
When a plastic molding company conducts plastic injection molding, they should not blindly produce based solely on the advantages of this process, but also fully understand the structure of their equipment to provide customers with better injection molding services.
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