In principle, as long as the mold design is combined with the performance of plastic parts, almost all thermoplastics can be molded by hot runner injection molding, but currently the most widely used in hot runner injection molding are polyethylene, polypropylene, polystyrene, Polyacrylonitrile, polyvinyl chloride, ABS, etc.
There are no such runner aggregates in the hot runner injection mold. For thermosetting plastics, this part of the plastic consumes less; for thermally explicit plastics, the recycling of these aggregates is eliminated, so there is no need to condense these. The material is separated from the plastic parts, monumental, extruded, and pelletized, which saves the energy consumption and labor required for each process in these tasks. Without runner condensate, a smaller opening stroke and smaller projection area can be selected in the mold design, and a smaller injection molding machine can be selected for the same plastic part. Not only the equipment cost is reduced, but the motor, pump, and material of the injection molding machine are also reduced. Simple heating power is small.
When using the hot runner gating system to form plastic parts, the raw material properties of the plastic parts are required to have strong adaptability, which is reflected in the following points.
①The thermal stability of plastic is better. Plastics have a wide melting temperature range, small viscosity changes, and are not sensitive to temperature changes. They have better fluidity at lower temperatures and are not easily thermally decomposed at higher temperatures.
② The melt viscosity of plastic is sensitive to pressure. The plastic part does not flow when the injection pressure is not applied, but the plastic part will flow when the lower injection pressure is applied.
③ The curing temperature and heat distortion temperature of plastics are relatively high. Plastic parts can be cured at a relatively high temperature to shorten the molding cycle.
④The small specific heat capacity of plastic can not only condense quickly, but also melt quickly.
⑤ The thermal conductivity of plastics is better. The heat from the resin can be quickly transferred to the mold to accelerate curing.
Post time: Nov-25-2021