TPU (thermoplastic polyurethane) is a thermoplastic elastomer. Its injection molding temperature is a key process parameter, which directly affects the quality and performance of the product. When determining the injection molding temperature of TPU, multiple factors need to be considered, including the type of TPU, the size of the pellets, the design of the mold, and the performance of the injection molding machine.
Generally speaking, the injection molding temperature of TPU ranges from 180°C to 230°C. The specific temperature setting depends on the specific type of TPU. For example, some high-hardness TPUs may require a higher molding temperature, while low-hardness TPUs may require a lower molding temperature.
During the injection molding process, the barrel must first be preheated to fully melt the TPU pellets in the barrel. The preheating temperature is usually set within the recommended molding temperature range of TPU to ensure uniform melting of the pellets and avoid the production of unmelted pellets or premature thermal degradation.
In the molten state, the TPU is pushed into the mold by the screw of the injection molding machine. In the mold, the TPU fills the mold cavity under pressure to form the desired product shape. The temperature of the mold is also an important factor affecting the quality of the product. Generally speaking, the mold temperature should be set within a lower temperature range to promote the rapid solidification of TPU and avoid problems such as deformation or shrinkage of the product.
In the injection molding process, injection pressure and time are also parameters that need to be controlled. The size of the injection pressure directly affects the density of the product and the uniformity of the internal structure. Too long an injection time may cause problems such as roughness or flow marks on the surface of the product, while too short an injection time may cause problems such as voids or incomplete filling inside the product.
In addition to the above process parameters, the selection of the injection molding machine is also crucial. The tonnage, screw speed, injection speed and other parameters of the injection molding machine will affect the injection molding process of TPU. Therefore, when selecting an injection molding machine, it is necessary to make a comprehensive consideration based on factors such as the size, shape and complexity of the product.
In short, determining the injection molding temperature of TPU is a comprehensive process that requires consideration of multiple factors. In actual production, it is necessary to adjust and optimize according to specific production conditions and product requirements to obtain the best product quality and performance. At the same time, reasonable process parameter settings and the selection of injection molding machines are also key factors to ensure product quality. Through continuous practice and experience accumulation, we can gradually master the optimal process parameters of TPU injection molding and improve the product qualification rate and production efficiency.