Hot runners are already indispensable in injection molding. For plastics processors, choosing a right hot runner for molding of product and mastering proper use of hot runner is the key to its benefit from hot runner.

 

Hot runner (HRS) is also called hot nozzle, which turns solidified nozzle into a molten nozzle. Its composition is relatively simple, mainly including splitter plate, hot nozzle, temperature controller and so on. Among them, splitter plate can be divided into work shape, X shape, Y shape, T shape, mouth shape and other special shapes according to shape; hot nozzle can be divided into a large nozzle, a tip nozzle and a needle valve nozzle according to shape; temperature controller can be divided into watch core type, plug-in type and computer centralized control according to temperature control mode.
In injection molding, hot runners work in conjunction with molds and play a very important role. For example, in injection molding of ultra-thin parts (such as mobile phone battery covers), high-precision, high-quality products can be easily produced by using hot runners; for injection molding materials with poor fluidity (such as LCP), flow of raw materials can be significantly improved by using hot runners to ensure smooth production of injection molding; For some large injection molded parts, such as bumpers and door panels of automobiles, rear casings of TV sets, air-conditioning enclosures, etc., use of hot runners makes very difficult injection molding relatively simple.
In mold injection molding of multi-cavity, it cannot be formed at all if lack of hot runners. It can be said that hot runner is the best technology to ensure balance of runner. Due to shearing force of plastic in flow channel, no matter reasonable geometric balance of mold, weight of formed product is difficult to be consistent, especially for multi-cavity mold. If hot runner is not used in plastic mold design, outer side of formed product will be lighter than inside.
For plastics processors, use of hot runners is quite economical as long as there is a certain amount of injection molding. This is because hot runners help companies eliminate nozzles in injection molding. In most cases, nozzle cannot be reused. Sometimes weight of nozzle is almost same as weight of product. If traditional nozzle injection method is used, it means that wasted material is as much as raw material used in product. Based on this calculation, after using hot runner, it can save 30% to 50% of raw materials. In addition, hot runners help to reduce mold wear and extend life of mold. In general, service life of hot runner mould is twice that of thin nozzle molds.
Although composition of hot runner is relatively simple, each component plays an important role. Generally, a good quality hot runner has high requirements for structural design and materials.
In addition, hot runner suppliers need to help customers design and install suitable hot runner systems based on customer's plastic products and mold used. For example, in plastic mold design of hot runner for injection molding of Shanghai General Motors door panel, relevant components of hot runner are selected on the basis of fully considering materials used for door panel.
If door panel is made of PP material, usually a 3-point hot runner can be used, that is a Y-shaped splitter plate and three hot nozzles are used. This scheme greatly reduces manufacturing cost under premise of ensuring molding quality of product; if door panel uses fireproof ABS in the case of materials, it is necessary to use a 5-point hot runner, that is a special splitter plate and five hot nozzles to ensure smooth formation of product.

 

When installing hot runner, you need to pay attention to following points:
● Full inspection of hot runners, including all dimensions, resistance, and quantity;
● Size of relevant part of mold and hot runner;
● Before installing panel, hot runner must be carefully detected with a thermostat to confirm that it is working properly before it can be operated on machine;
● Before production, hot runner must be checked with a multimeter, otherwise it is not allowed to start;
● It must be air-blasted before clamping. When air-blasted, cover B-plate mold with cardboard, and then close mold for testing.
To help customers use hot runners properly, hot runner suppliers should train their customers. Training content should include:
● Basic principle of hot runners. Hot runner keeps plastic in flow path in a molten state by means of electric heating. Here, it is necessary to emphasize to customer that when hot runner is working in hot runner mould, it is necessary to have good insulation measures. For this reason, it is not possible to replace square iron when making manifold cavity, which is very important in injection molding.
 ● Learn to properly install and disassemble hot runner. First of all, customer must understand sealing position of hot runner. It includes sealing of hot nozzle and manifold, sealing of hot nozzle and A plate, sealing of main nozzle and panel, sealing of valve needle and valve guide sleeve, sealing of main nozzle and heat flow plate.
● Maintenance of hot runners. Let customer realize that once hot runner has a problem, it must be removed from hot runner mould for repair, which takes at least 8 hours. For customer, cost of loss is about 10 times that of hot runner supplier. Therefore, it is very important to maintain a hot runner by a full-time or part-time staff.