Plastic mold hot runner system, also known as hot runner system, is mainly composed of hot gate sleeve, hot runner board and temperature control electric box. Common hot runner system has two forms of single-point hot gate and multi-point hot gate.
Single point hot gate is to use a single hot gate sleeve to directly inject molten plastic into the cavity, it is suitable for single cavity single gate plastic mold;
The multi-point hot gate is to branch the molten material into the hot gate sleeve through the hot runner plate and then enter the cavity. It is suitable for single cavity multi-point feeding or multi-cavity mold.
Advantages of plastic mold runner system
- (1) No nozzle material, no post-processing is required, so that the entire molding process is fully automated, saving working time and improving work efficiency.
- (2) Low pressure loss. The temperature of the hot runner is equal to the temperature of the injection nozzle of the injection molding machine, which avoids the surface condensation of raw materials in the runner and the injection pressure loss is small.
- (3) The repeated use of nozzle materials will degrade the performance of plastics, and the use of hot runner system without nozzle materials can reduce the loss of raw materials and thus reduce product costs. In the cavity, the temperature and pressure are uniform, the stress of the plastic part is small, and the density is uniform. Under a lower injection pressure and a shorter molding time, a better product is injected than the general injection system. For transparent parts, thin parts, large plastic parts or high-demand plastic parts, it can show its advantages, and it can produce larger products with smaller models.
- (4) The hot nozzle adopts standardized and serialized design, and is equipped with various nozzle heads for selection, with good interchangeability. The uniquely designed and processed electric heating ring can achieve uniform heating temperature and long service life. The hot runner system is equipped with hot runner plates, thermostats, etc., with exquisite design, various types, convenient use, stable and reliable quality.
The shortcomings of the application of plastic mold hot runner system
- (1) The closing height of the overall mold is increased. Due to the addition of hot runner plates, the overall height of the mold has increased.
- (2) The heat radiation is difficult to control. The biggest problem of the hot runner is the heat loss of the runner, which is a major problem to be solved.
- (3) There is thermal expansion, and expansion and contraction are issues we must consider when designing.
- (4) Increased mold manufacturing costs and higher prices of standard accessories for hot runner systems have affected the popularity of hot runner molds.