injection mold and blow molding differences and similarities
Injection mold and blow mold design similarities and differences, we should pay attention to what?
1. The process is not the same, injection blow molding is blowing +; + Injection molding is injection pressure; rotomolding is crowded + pressure; blow that must have to do to pull the blow pipe leaving the head must have done the injection gate section, Rotational crop does not necessarily have burrs
2. In general, injection molding is a solid core, blow molding and rotational molding is empty core. Injection surface is bright, blow molding and rotational molding surface is uneven. Rotomolding and blow-blow comparison of minimum there are inflatable mouth. this saying is general to compare. I do not know whether you can understand !!!
3. Plastic shrinkage and its influencing factors
Characteristics of thermoplastics is expanded after heating, cooling contraction, of course, the volume will be reduced after the pressing. In the injection molding process, molten plastic is first injected into the mold cavity, after the melt is cooled and solidified filling, i.e. contraction removed plastic parts from the mold, the molding shrinkage is called contraction. Plastic removed from the mold into the stable this time, the size will still be minor changes, a change is to continue to shrink, the shrinkage is called contraction. Another variation is that some plastic hygroscopic arising from expansion due to moisture absorption. E.g., nylon 610 water content of 3%, 2% increment size; glass fiber reinforced nylon 66 has a moisture content of 40% when the size of the increment of 0.3%. But which play a major role in molding shrinkage.
Currently identified various plastic shrinkage (shrinkage + post-molding shrinkage) methods are generally recommended German national standards set forth in DIN16901. After that is placed 23 ℃ ± 0.1 ℃ when the size of the forming mold cavity for 24 hours, the difference between the measured temperature of 23 ℃, relative humidity of 50 ± 5% under the conditions of the respective size of the plastic parts is calculated.