The design of the cooling system is very important in i […]
The design of the cooling system is very important in injection moulding. This is because the moulding of the plastic product is only cooled to a certain degree of rigidity, and then the plastic product is released from the Table Mould to avoid deformation due to external force. Since the cooling time accounts for about 70% to 80% of the entire injection moulding cycle, the design of a good cooling system can greatly shorten the moulding cycle time, increase the injection moulding rate and reduce the cost. Improper cooling system design can make cooling times longer, and even more cooling time can exacerbate the warpage of plastic products.
According to the experiment, the heat transferred from the melt to the table mould is usually divided into two parts, one part is 5%, transferred to the atmosphere by radiation and convection, and the remaining 95% is from the melt into the table mould. Due to the effect of water cooling, the heat in the plastic cavity is transferred to the cooling water pipe by the convective heat carried away by the coolant. The remaining heat that is not cooled by water continues to be conducted into the mould, and the mould is dispersed in the air.
The cycle of injection moulding consists of the closing time, filling time, holding time, cooling time and injection time. The cooling time accounts for the largest proportion of the moulding cycle, which is about 70% to 80%. Therefore, the cooling time will directly affect the moulding cycle time and output rate of plastic products. The temperature of the plastic product in the release stage should be lower than the heat distortion temperature of the plastic product to prevent residual stress and deformation caused by external force.