Needle Valve Preform Mould Reduce Cycle Time
Needle Valve Preform Mould TPU the most appropriate means of processing than screw-type injection molding machinery. With the usual length of the single thread, three screws can produce a good plasticized uniform melt. If you need high plasticizing capacity (production), you can use a longer screw.
The short compression zone screw is not suitable due to high shear. TPU plasticization requires high energy, requiring a high torque drive for the screw. Insufficient torque will cause the screw speed fluctuations and plasticization of the uneven. Within the limits, the higher barrel temperature will produce good results, although it will risk the overheating of the material.
The nozzle and the head of the nozzle should be designed without dead ends, allowing the material to be injected without heat damage. The precise temperature control of the heating system of the barrel and the nozzle is essential. Make sure that the nozzle is heated evenly throughout the length. Beware of local overheating of the melt and possibly cold. The molten TPU is either non-corrosive or wear-free. For this reason, the screw does not require any special alloy steel or reinforced coating.
2.1 injection unit
The TPU should be machined at a melting temperature between 190 and 220 ° C. For some hard grades the melting temperature may rise to 240 ° C. The specific temperature range of the TPU can be found in the relevant product information sheet.
The main effect of mold temperature is surface quality and demolding behavior. He also affects the final structure of the contraction and internal stress when the cold). Normal mold temperature application 20 - 40 ° C. But with some improved TPU level and the use of glass filled with enhanced TPU,Needle Valve Preform Mould the mold temperature should be increased to 60 ° C to ensure the best surface quality. For cooling of thick-walled items, reducing the cycle time by about 5 ° C can be reduced.
For the plasticization rate should be selected circumference rate of not more than 0.3 m / s. The measuring stroke should be between 1 D and 4 D. The practical experience is to utilize the screw with 30 - 75% capacity is the best. If the barrel capacity corresponds to a very low injection volume,Needle Valve Preform Mould the melt remains in the plasticizing unit for too long. Will cause heat damage to the melt.
Injection pressure, holding pressure, back pressure, injection speed
For the ideal processing, the main point is the pressure and the injection speed of uninterrupted control. It should be able to control the injection and hold pressure in the range of 100 to 1200 bar. For homogenization there must be back pressure, usually set between 1 and 2.5% of the injection pressure. Injection speed is mainly based on wall thickness. Usually the mold for thick-walled items needs to be filled slowly, and the thin-walled items need to be filled quickly.
For injection speed In addition to wall thickness and mold type, mold exhaust plays an important role, which helps to avoid the so-called "burn marks" caused by high pressure hot air. Injection pressure / holding pressure exerts a greater effect in space stability and mold release. Excessive injection pressure during molding,Needle Valve Preform Mould while too low to maintain the pressure to produce a dent. It is more difficult to mold overload. It is advisable to work with the wrong pressure, that is, to maintain the pressure at a lower pressure than the injection pressure. By rule, the holding pressure of 50% of the pressure is appropriate. This can produce items with minimal internal pressure.
1, Needle Valve Preform Mould hot runner is not limited by the replacement of injection molding materials.
2, can shorten the processing cycle, improve production efficiency.
3, Needle Valve Preform Mould hot runner at the injection port of the thermal shear phenomenon is reduced.
4, Needle Valve Preform Mould hot runner plastic injection molding at low temperatures possible.
5, Needle Valve Preform Mould hot runner at each injection port to control the amount of plastic injection possible.
6, Needle Valve Preform Mould hot runner due to the small pressure loss, it is suitable for a variety of plastic products.
7, progressive product consistency, no prominent gate marks, completely put an end to the mouth salivation, no drawing phenomenon.
8, Needle Valve Preform Mould hot runner low pressure injection injection molded products in the shrinkage of a smaller size significantly improved the appearance of the product.
9, help to reduce product stress, reduce product deformation and structure caused by brittleness, thereby improving the complex structure of the production capacity and service life.
10, the mold hot runner because of the replacement of the cold runner, does not produce material to the (nozzle material), no need to break the destruction, can save a lot of raw materials, plastic materials, waste reduction, injection molding products to improve the quality and more stable.