Chinese
English
The processing method suitable for transparent TPU material is screw injection molding machine. The three-stage screw uses a single thread of normal length to produce a very good plasticized melt. Longer production capacity of the screw can be used if required. Short compression zone screws are not suitable due to high shear. TPU plasticization requires high energy and high torque driven by screws.
Insufficient torque will lead to screw speed fluctuation and uneven plasticization. Within this limit, higher barrel temperatures can produce good results despite the risk of overheating the material. The channel of nozzle and barrel head shall be designed without dead angle, so that the material can be injected without thermal damage.
The key is to accurately control the temperature of the heating system of the barrel and nozzle. Take care to ensure that the nozzle heats evenly over the entire length. Beware of local overheating and possible cold of the melt on the path. The molten TPU is not corrosive or abrasive. Therefore, the screw does not need any special alloy steel or reinforced coating.
Temperature setting of barrel and die? The melting temperature of TPU shall be between 190 and 220 ° C. For some cemented carbides, the melting temperature may increase to 240 ° C. the melting temperature range of specific grade TPU can be found in the relevant product information table. The main influence of mold temperature is surface quality and demoulding behavior.
