Hot runner product introduction
1 by controlling the opening time of the gate, ensure the cavity filled with smooth and melt flow balance, eliminate weld marks.
Injection molding manufacturing large injection parts usually require two or more hot runner to fill. For ordinary hot runner system, the gate will be opened at the same time as the injection begins. This glue is inevitable in the presence of fusion defects, namely in two strands of molten material striker confluence, due to the two strands of melt cannot completely fused as one, and the formation of fusion imprinting reaction WIP surface is commonly referred to as the melting marks. Although it can be improved by increasing the temperature of molten material, increasing the pressure of the pressure and adjusting the parameters of injection molding process, the effect is limited.
Using needle valve type hot runner technology to construct the gating system, you can realize the program control of the valve gate is opened and closed, and can be controlled in the first unit melt just through a second valve gate, opening a needle valve, open the second gate. At the same time, can according to need to open or close the first gate, always go on until all gates are opened and the cavity is full, the melt completely fused, no weld marks of products.
2 use the technology to obtain the products will not have residual gate traces, therefore, can be applied to the processing surface quality requirements of higher injection molding parts.
There are times when the valve gate is due to the valve gate on the part of the smooth, only equivalent to a top of the traces left by the pin, so it is much smaller than the potential type of runner and other types of hot runner ends.
3 more effective control of the holding pressure and forming cycle.
Needle valve type hot runner can use larger diameter of the gate, the melt in the mold cavity flow accelerated, so as to shorten the stamping forming cycle, and can better packing.
4 to reduce the internal stress and improve the stability of the products.
As mentioned earlier, the traditional hot runner system in two strands of melt flow front after confluence will weld line is formed, the result is not only affecting the product appearance, but also easy to produce a large residual stress in parts of internal. This stress concentration phenomenon will reduce the intensity of the product. If the valve gate control technology to control the melt into the order, it can effectively avoid the direct intersection of the melt flow front, thereby avoiding the stress concentration phenomenon, and thus improve the stability of the product.
In addition, the use of valve type hot nozzle can be prevented in the mold material suction and wire drawing (drawing) phenomenon.
Needle valve type hot runner system structure and principle
Needle valve type hot runner valve needle motion can be controlled by a spring and the use of pneumatic or hydraulic control, the structure of a variety of forms and diverse. For large injection molding of automobile bumper case, we usually use hot runner valve timing. Its stability is good, the opening and closing time of the gate is also relatively reliable.