Hot runner mold system structure is roughly the same as a fine sprue, the biggest difference is that the hot runner injection molding is in one or more hot runner system plates and hot nozzles with constant temperature, no cold material demoulding, runner and gate directly on the product.
So the hot runner system does not need to be demolded, this system is also called no sprue system, it can save raw material, it is suitable for the case where raw material is more expensive and the product is more demanding, the design and processing are difficult and the injection mold cost is higher.
The hot runner system, also known as the hot sprue system, mainly consists of a hot sprue sleeve, hot sprue plate, and injection molding temperature control electric box. The common hot runner system has two forms: single-point hot gate and multi-point hot gate.
Single point hot gate is to use single hot gate sleeve to shoot molten plastic into the cavity directly, it is suitable for single cavity single gate plastic mold; the multi-point hot gate is to branch the molten material into each sub hot gate sleeve and then into the cavity through hot gate plate, it is suitable for single cavity multi-point feeding or multi-cavity mold.
10 Advantages of hot runner system
Advantages of hot runner system 1. Save working time
No sprues, no post-processing, so that the whole molding process is fully automated, saving working time and improving working efficiency.
Advantages of hot runner system 2. Small pressure loss
The hot runner temperature is equal to the injection nozzle temperature, which avoids the surface condensation of raw materials in the sprue and low injection pressure loss.
Advantages of hot runner system 3. Reduce product cost
Repeated use of sprues will degrade the plastic performance, while using a hot runner system without sprues can reduce the loss of raw materials, thus reducing the cost of products.
Advantages of hot runner system 4. Uniform temperature and pressure in the cavity
With uniform temperature and pressure in the cavity, the plastic parts will have low stress and uniform density, which can produce better products than the general injection molding system in a shorter molding time with less injection molding pressure.
For transparent parts, thin parts, large plastic parts, or highly demanding plastic parts, it can show its advantages, and it can produce larger products with smaller models.
Advantages of hot runner system 5. Long service life
The heated nozzle adopts a standardized and serialized design, with various optional nozzle heads, and good interchangeability. Unique design and processing of electric heating rings can achieve uniform heating temperature and long service life.
Advantages of hot runner system 6. Shorten the molding cycle of parts
Since there is no limitation of cooling time in the sprue system, the parts can be ejected in time after injection molding and curing. Many thin-walled parts produced by hot runner molds can be molded in less than 5 seconds.
Advantages of hot runner system 7. Save plastic material
In a pure hot runner mold, there is no cold sprue, so there is no production cost. This is especially important for applications where plastic is expensive.
Advantages of hot runner system 8. Reduced costs and improved product quality
During the hot runner injection molding process, the plastic melt temperature is accurately controlled in the runner system. The plastic can flow more uniformly into each cavity, resulting in consistent quality parts. Hot runner molded parts have good gate quality, low residual stress after demolding, and low part deformation.
Advantages of hot runner system 9. Elimination of subsequent processes, conducive to production automation
The finished product is formed by the hot runner mold, so there is no need to trim the gate and recycle the cold sprue and other processes. It is conducive to production automation.
Advantages of hot runner system 10. Expand the application of the injection molding process
Many advanced plastic molding processes are developed on the basis of hot runner technology. Such as PET preform production, multi-color co-injection in the mold, a variety of materials co-injection process.
Disadvantages of hot runner system application
1. The overall mold closing height increases, due to the addition of a hot runner plate, etc., the overall height of the mold increases.
2. Heat radiation is difficult to control, the biggest problem of the hot runner is the heat loss of the sprue, which is a major issue to be solved.
3. There is thermal expansion, thermal expansion and contraction is a problem to be considered when we design.
4. The cost of mold manufacturing increases, the price of standard parts of hot sprue system is high, which affects the popularity of hot sprue mold.
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