Polyurethane Injection Molding | Key Technology
Polyurethane Injection Molding
Details
Details:
Model
Material
Brand
Origin
Application
Booling-Injection-12
P20, 718, S136, 2738 etc
Booling
China
Automotive parts, industrial parts, medical parts, household
Polyurethane injection molding technology is the molding of polymer materials, and its key technology mainly involves manufacturers injecting mixed raw materials into equipment and controlling temperature and pressure to shape them.
Advantages of Polyurethane Injection Molding：
- High Strength
- Wear Resistant
- Oil Resistant
- Stable Chemical Performance
- Good Elasticity Recovery
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Polyurethane injection molding is a process of injecting molten polyurethane plastic into a closed mold through the nozzle and screw of an injection molding machine, cooling and solidifying it, and then removing the finished product. The process of plastic injection molding can maximize the advantages of polyurethane, fully utilizing its physical and chemical properties to produce products with appearance and performance advantages.
Key Points to Note for Polyurethane Injection Molding
Polyurethane injection molding is a special technology, and before carrying out this process, attention should be paid to:
- The Influence of Moisture Content on Polyurethane Injection Molding
Although the water absorption rate of polyurethane materials during injection molding is not as high as particles such as PET, PC, Nylon, etc., TPU materials are affected by their polar bonds, and the amount of water absorbed increases with the increase of hardness. During injection molding, the processing temperature of polyurethane is usually maintained between 180~230 ℃. In such a high-temperature processing environment, the molecular bonds of polyurethane will undergo reverse reactions, releasing R-NCO functional groups. If the material is not sufficiently dried before injection molding, the R-NCO functional group will react with water and produce carbon dioxide. This situation not only causes the original polyurethane molecular bonds to break, resulting in a decrease in physical properties but also leads to defects in the appearance of processed products. The pressure caused by the generation of gas will also affect the operability of processing, making the forming process more difficult. In addition, the moisture content of materials greatly affects the physical properties of the parts, so it is necessary for manufacturers to thoroughly dry the plastic particles before processing, preferably until the moisture content is below 0.03%.
- Recycling Processing
Polyurethane can be processed using or mixed with recycled materials during both extrusion and injection processing. The proportion of recycled materials involved depends on the physical properties of the recycled materials, and the general principle for addition is not to exceed 25% of the total amount. Whether it is injection or extrusion processing, manufacturers first need to dry the recycled material and mix it thoroughly with the new material. Recycled materials and new materials are subjected to temperature and screw shear force in the material barrel. Only by processing the uniformly mixed homogeneous melt can ideal processed products with both usability and appearance properties be obtained.
Types of Polyurethane for Injection Molding
There are various types of polyurethane materials used in injection molding, which can be mainly divided into:
- Soft Polyurethane Foam
Manufacturers widely use this polyurethane material in a range of consumer and industrial products to provide cushioning. For example: vehicle interior, packaging, furniture, mattresses, etc. This polyurethane has strong plasticity and flexible injection molding methods. Manufacturers can adjust its hardness through additives. This soft polyurethane is lightweight, sturdy, comfortable, and can provide support.
- Rigid polyurethane Foam
The heat insulation of this foam can minimize energy loss and provide more comfort for families and commercial real estate. To solve the high electricity cost caused by heating and cooling, manufacturers apply rigid polyurethane foam to injection molding of isolation walls, windows, doors, and roofs, which can well isolate noise and achieve uniform temperature.
- Thermoplastic Polyurethane (TPU)
Thermoplastic polyurethane is a highly flexible, durable, and elastic injection molding material that can withstand significant impacts and extreme weather conditions, with strong resistance to wear and durability. These characteristics and advantages make the manufacturing and use of thermoplastic polyurethane flexible and diverse, and adding it to products can improve its durability. TPU is a thermoplastic that can undergo melt processing, as well as injection molding, extrusion, blow molding, and compression processes. Thermoplastic polyurethane provides countless combinations of physical properties and flexible processing methods, which can be applied to various industries from construction to footwear, from daily consumer goods to precision fields.
- Coatings, Adhesives, Sealants, and Elastomers
Polyurethane elastomers are relatively light weight, can resist various environmental factors (with a wide range of temperature resistance), recover faster and more effectively from pressure after being subjected to force, and can be molded into various shapes. Adding a certain amount of polyurethane to some special products can help extend their service life and improve their appearance performance. Polyurethane sealant helps to seal more firmly, while polyurethane adhesive helps to bond firmly.
- Reaction Injection Molding (RIM)
The polyurethane RIM process can produce components that traditional injection molding processes cannot produce, and is widely used in the manufacturing and molding of telecommunications equipment, electrical housing panels, automotive bumpers, and more. Polyurethane RIM components have the characteristics of light weight, durability, dimensional stability, heat resistance, thermal insulation, and dynamic performance. From furniture to cars, from construction to sports equipment, RIM parts are active in various industries. The emergence of this process enhances the flexibility of design and facilitates the production of wall components (thick or thin), foam cores, and encapsulated interiors.
Comparison between Polyurethane Injection Molding and Casting
Different production processes: The pouring process directly pours the polyurethane liquid mixture into the mold, while polyurethane injection molding injects molten material into the mold through an injection molding machine, resulting in significant differences in processing methods.
Differences in product characteristics: Products produced by polyurethane injection molding and casting processes have similar performance, but specific characteristics may vary due to differences in production processes and raw material formulations.
Different application fields: Polyurethane injection molding and casting processes are widely used in multiple industrial fields, but specific usage scenarios may vary depending on product shape, size, and performance requirements.
Polyurethane injection molding plays an indispensable role in multiple industries in China due to its unique process flow and technological advantages, providing efficient and high-quality injection molding solutions for various products.
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