Hot runner heat shield, which is made of composite material with low thermal conductivity, is specially designed for the molding industry, with both heat insulation and compression resistance effects. The heat shield is placed between the mounting plate and the fixed plate on the top of the mold or between the injection base and the moving template of the injection molding machine, the purpose is to reduce the heat transfer from the mold to the mounting plate (the direction of the transfer depends on the type of the mold) to stabilize the temperature of the surface of the mold cavities, to ensure the quality of the products, to reduce the loss of heat, and to prolong the service life of the equipment. The next step is to introduce you to the identification of mold heat insulation board and mold heat insulation board purchase.
Hot runner heat insulation board identification method
1, look at the hot runner heat insulation board thermal stability
High temperature will make the organic components of the internal oxidation degradation of heat insulation materials. Therefore, high-quality heat insulation board materials need to withstand long repeated high temperature and high pressure test, continuous resistance to thermal and mechanical stress within the system, in general, high-quality mold heat insulation board materials usually have an average service life of 3-5 years.
2, look at the thermal conductivity of the hot runner heat insulation board
This is a very important technical parameter of the mold insulation board material, which represents the thermal insulation effect of the insulation material. The lower the coefficient of thermal conductivity, the better the thermal insulation performance of the material.
3, look at the hot runner heat insulation board in the long-term high temperature and high pressure environment is not deformed
Most of the main components of the thermal insulation materials are organic polymers. Compared with inorganic materials, organic materials usually have better toughness, and are not easy to crack when subjected to thermal stress. However, in a high-temperature environment, the thermal stability of organic materials will degrade over time, that is to say, although the organic material will not occur instantaneous softening, fracture and melting, but its life expectancy will be reduced as the temperature rises, so the dimensional stability of the material to withstand a long period of thermal stress is an important reference index for the selection of thermal insulation panels. In general, good thermal stability of the material, after withstanding 5000 hours of high temperature, deformation is less than 1%.
4, look at the hot runner heat insulation board in z high application temperature compressive strength
Usually, the compressive strength of the hot runner insulation board material is measured at room temperature. As the temperature rises, the compressive strength of the material will drop sharply. When selecting a heat shield material, engineers need to refer to the compressive strength at a set application temperature. For example, if an organic material has a z-high application temperature of 350 degrees Celsius, its compressive strength at 350 degrees Celsius will drop to less than 100 MPa if it has a compressive strength of 300 MPa at room temperature. On the contrary, if the z-high application temperature of an inorganic material is 1500 degrees, then its compressive strength at room temperature and 1500 degrees is almost equal and the difference is negligible. In the selection of mold insulation materials, mold engineers need to be based on their own process requirements, such as temperature and pressure, to screen their own needs for cost-effective insulation board.
5, look at the hot runner insulation board water absorption rate
Water absorption will bring negative impact to the performance of hot runner heat insulation board material, there are two main reasons: first, the temperature is higher than 100 degrees, the water content of the material produces higher vapor pressure, resulting in material rupture, this phenomenon is very common in the water content of more than 10 materials; second, the water absorption rate affects the material’s thermal insulation performance. Dry materials have a lower thermal conductivity compared to wet materials. In the cooling phase of the system, the material water absorption phenomenon will cause the system to warm up again, water evaporation consumes additional heat.
6, look at the tolerance of the hot runner heat insulation board
Fiber reinforced materials, on the dimensional stability is far better than metal materials. Of course, the mold heat insulation plate material is not possible to maintain a certain non-deformation, therefore, engineers choose the heat insulation plate, the tolerance has strict requirements. It must be emphasized that in most cases, the temperature of the insulation board is much higher than room temperature. The deformation of mold insulation board materials is not caused by thermal expansion, but by drying, curing or oxidation of the material.
