The key to high gloss injection molding is the mold temperature control system. The biggest difference between high-gloss injection molding and general injection molding is the control of mold temperature, and the requirements for injection molding machines are not high. The high-gloss injection mold temperature control system is commonly referred to as a high-gloss mold temperature machine, which cooperates with a general-purpose injection molding machine to coordinate actions during the filling, pressure maintaining, cooling, and mold opening and closing processes of injection molding.
The heating method of the mold surface is the key technology of the temperature control system. The high gloss mold surface mainly obtains heat through the following methods. One is a heating method based on heat conduction, such as conducting heat to the surface of the mold through oil, water, steam, and electric heating elements in the internal pipes of the mold; The second is a heating method based on thermal radiation, such as directly radiating solar energy, laser beams, electron beams, infrared light, flames, gases, etc. onto the mold surface; The third is to heat the mold surface by its own thermal field, such as through resistance and electromagnetic induction heating. Currently, practical heating systems include: oil temperature machines for high-temperature oil heat transfer, high-pressure water temperature machines for high-temperature high-pressure water heat transfer, steam mold temperature machines for steam heat transfer, electric heat mold temperature machines for electric pipe heat transfer, electromagnetic induction heating systems, and infrared radiation heating systems.
(l) Oil temperature machine for high-temperature oil heat transfer (Daheda brand)
Uniform heating or cooling pipes are designed inside the mold to achieve the effect of preheating the mold through an oil heating system, while cooling during the injection process. The maximum temperature can reach 350 ℃. Due to the low thermal conductivity of oil, its efficiency is low, and the generated oil and gas affect the quality of high gloss molding, but the effect is not ideal. However, at present, oil temperature machines in enterprises are relatively common and have rich experience in use.
(2) High pressure water temperature machine with high temperature and high pressure water for heat transfer (Daheda brand)
The interior of the mold is designed with balanced pipes, and water at different temperatures is used at different stages. During heating, high temperature superheated water is used, and during cooling, it is switched to low temperature cooling water to achieve heating or cooling of the mold surface. If water is pressurized, the temperature rise can also reach 140 to 180 ℃, and the temperature rises quickly. Manufacturers of high temperature and high pressure water temperature control systems include the GWS system of Ohata, which is widely used in the domestic market and is the best choice to replace steam due to its recyclable hot water and low operating costs.
At present, there are still some problems to be solved in the temperature control system. One is that there are few practical heating methods, and the more successful ones are high-temperature water heating. The other is that high gloss injection molding uses a separate mold temperature control system, which needs to be used in conjunction with the injection molding machine. Third, high equipment and operating costs. How to enable the variable mold temperature control technology to carry out economic scale production without affecting the molding cycle is a topic that everyone strives to develop and break through. In the future, it is necessary to further research and develop practical low-cost rapid heating methods, integrated high-gloss injection molding machines, and other aspects.
From the perspective of mold temperature control machine, it is also known as steam mold temperature machine, superheated water mold temperature machine, electric mold temperature machine, water temperature machine, oil temperature machine, electromagnetic induction mold temperature machine, etc.