Although hot runner and injection mold are a whole, its role and function are completely different from mold itself. For independent unit composed of system, its installation, connection and operation have special high-precision position requirements.
For these reasons, assembly of hot runner system has become a bottleneck for mold installation. Therefore, avoiding errors in installation process of hot runner system, simplifying system connection and saving assembly time have become a very important issue.

 

Hot runner system is derived from hot runner system. Usually, nozzle is not always installed on manifold, can also be connected to nozzle flange, but this type of system requires a fixed plate to maintain integrity of system. For most plastic processing processes, since temperature of mold is close to 200°C, there is a temperature difference between hot runner and mold. If system is connected to mold plate, it will increase temperature and increase heat loss, there may also be a dead angle of flow between manifold and nozzle.
When hot runner needs to be repaired, hot runner must be completely removed from mold. Since nozzle is not connected to manifold, electrical and hydraulic lines must be completely disconnected, connected after overhaul.

In combined hot runner system, nozzle and manifold form a simple unit. Melt flows directly into nozzle from manifold, so there is no deviation and flow dead angle. Threaded nozzle is embedded in manifold, eliminating leakage between nozzle and manifold. Traditional bushing system design will produce thermal expansion, and this combined system is particularly effective in eliminating such leakage.
Combined hot runner system is located in the center of mold and has very little connection with mold. Its manufacturing material does not require high thermal conductivity, nor does it require clamping and pretensioning of mold piece. This minimal connection provides a high-precision and stable temperature profile, so energy consumption is much lower than that of traditional hot runner system.
Combined hot runner system can directly pre-assemble hydraulic circuit independent of mold. Valve port directly driven by hydraulic equipment can also be directly installed on the system, so that control valve on traditional machine is omitted, making injection molding more flexible. In addition, electrical and hydraulic circuits can also be configured according to customer requirements. Since system will undergo electrical, temperature, hydraulic or pneumatic testing before delivery, customer will be provided with instructions for pre-installing the system so that it can be easily installed in mold and immediately put into production.
When mold or system requires regular maintenance, combined hot runner system can also be removed from mold in simple steps, so that it can be repaired and inspected independently of mold.
Generally, combined hot runner system reduces maintenance costs. Complete hot runner system is based on combined pre-configured design and installation, heater or thermocouple wire is removed during assembly process.
Wire connecting heater and distribution box is placed in a specially designed conduit, which is very beneficial for disassembly of mold or hot runner system. At the same time, integrated hot runner system can carry out daily maintenance without disassembly, thereby saving time and reducing chance of assembly errors.

Hot runner technology, with its unique technical advantages such as cost saving and shortening of molding cycle, has become an important field of plastic injection molding process.
Advantages of hot runner technology compared with conventional cold runner:
Save raw materials and reduce costs;
Shorten molding cycle and improve machine efficiency;
Improve surface quality and mechanical properties of products;
Point gates can be used without using three-plate molds;
A single product can be economically molded with a side gate;
Increase degree of automation;
Needle valve gate can be used to control gate for freezing;
Quality of injection molded parts of multi-cavity mold is consistent;
Improve surface aesthetics of injection molded products.
Installation of hot runner is directly related to quality of product. Following are precautions for installation of hot runner:
Place mold, level upper mold, clean all holes and mold plates with an air gun.
Check size of each hole, focus on depth, and remove burrs on mold plate. At the same time, check whether screw holes of lock splitter plate, center nail and anti-rotation pin hole are finished. Master who makes hot runner mold for the first time in this place often misses it.
Sweep hot nozzle sealant position and upper step position which are matched with mold.
Try to install hot nozzle, then remove it to check whether sealant position rubs red lead and whether step position touches mold. If not, stop installation, check cause of error and make adjustments to ensure that fit is tight and does not leak materials. Be careful not to hurt tip of  nozzle during this process.
Install all hot nozzles, install center pad, center pin, and anti-rotation pin at the same time, sweep red lead on its plane.
Check nozzle plane and height of center pad, error should be controlled within 0.05mm.
Trial assembly of manifold. Be careful not to miss hot nozzle seal when installing manifold.
Check coordination of manifold and hot nozzle to ensure that all red lead is touched to ensure that there is no leakage of glue.
Arrange wiring of hot nozzle to be neat and beautiful, number each group of wiring in order, and connect wiring to plug.
Formally install manifold, tighten screws of manifold (note that balance must be locked to keep four corners of manifold at same height), control manifold meson to be 0.10-0.15mm higher than plane of peripheral mold frame, and then sweep red lead on the manifold..
Try to install code mold plate, check whether plane touches meson red lead, and make sure that mold plate presses manifold meson.
Lock mold, stand mold up, and check from parting surface whether fit between gate and tip of nozzle meets requirements. Tip should be 0.1-0.2mm lower than gate surface and tip should not be eccentric. Use a multimeter to carefully check each group of circuits to ensure that there is no short circuit, open circuit, leakage, etc., and each group of circuits corresponds correctly to ensure that all circuits are normal.
Connect thermostat to test heating, first heating should be within 100℃, keep it for ten minutes for preheating and dehumidification, protecting heater; then, heating to required temperature, if normal, you can arrange lifting and test mold.