It has been successfully used to process all kinds of plastic materials. For example: PP, PE, PS, ABS, PBT, PA, PSU, PC, POM, LCP, PVC, PET, PMMA, PEI, ABS/PC, etc. Any plastic material that can be processed with cold runner moulds can be processed with moulded hot runners. Thus, the characteristics about the plastic are extraordinarily important. For example: ablation temperature, pressure, viscosity, specific heat ......, etc. should be paid attention to. Because the scope of the plastic is very wide, here can not be deep in it, but we will be for its knowledge part to clarify.
1. Mould hot runner forming premise
The following is the moulding premise of common shape plastic. For each kind of different plastic, its relative moulding area may be different, but its process analysis is the same. Therefore, a good mould designer should investigate the moulding area and processing characteristics of each plastic.
2. Mould hot runner melt plastic activity
Ordinary fluid (for example: water, oil ......) its activity form, are in accordance with the Newtonian boundary. And plastic melt seems to be a common fluid, in fact, is a long and short Newtonian fluid. For example: in the Newtonian fluid, although the shear stress has shifted, but its viscosity is unchanged. And plastic melt, when the shear stress shifts, viscosity also has a clear shift occurs. For example: in the Newtonian fluid, the pressure is increased from 1 to 10, the outflow is increased by 10 times. Plastic melt to do the same implementation, when the pressure is added from 1 to 10, the outflow can be added 100 times, or 500 times, or even 1000 times (depending on the different plastic).
3. mould hot runner plastic material selection
The design of the finished product should be selected at the beginning of the plastic used, but most of the mould is not taken into account. But if possible, the material selected should make the mould manufacturing simple before good. Forming shortening rate of small (PS, ABS, PC) dimensional accuracy is easier to achieve. And the forming shortening rate of large (PP, PE, POM) is more difficult to achieve dimensional accuracy (the male service of the mould is 1/6 of the male service of the moulded products). The viscosity of the activity is relatively large (ABS, etc.), the solution is not easy to flow into the cracks, but the viscosity of small (such as PA, POM) even if the gap is very small solution is also easy to enter.
The lower forming temperature (PS, etc.) is easier to form and the forming cycle is faster, but the higher forming temperature (PC) is slower.
Post time: Nov-07-2022