blow molding
If you are searching for any of the following topics: Look no further. You'll find it at Blow Molding Consulting! information for processors in the area of extrusion and injection stretch blow molding of PET and OPP. There are 4 different types of blow molding that use material such as HDPE, PVC, PET, PP and others:: 1. Extrusion blow molding 1.1. Continuous extrusion 1.2. Reciprocating screw extrusion 2. Injection stretch blow molding of PET, OPP, and PC containers 2.1. Single stage injection stretch blow molding 2.2 Reheat stretch blow molding 3. Injection 4. Rotational
OPTIMIZING COOLING PARAMETERS
Water pressure, flow and temperature all affect the cooling of the heated plastic inside an injection or blow mold.
In terms of flow, there is laminar and turbulent flow. Both types of flow feature the maximum water velocity in the center of the pipe, however with turbulent flow the difference between the maximum water velocity in the center and the minimum velocity at the inside of the pipe or channel is less. Because we want a high water speed at the outside of the pipe or mold channel. turbulent flow is preferable to laminar flow. 6 bar water pressure is a must for all injection molding of PET preforms. The reason is that the water has to travel through rather small cooling pipes that take it to the front of the injection cores and then back around this pipe. The diameter of these pipes can be as small as 3 mm or 1/8" and even smaller for neck finishes below 20 mm. During the injection process, the PET will shrink away from the cavity wall in less than a second so the core cooling is the most crucial part of the cooling process. Insufficient water pressure will reduce the flow to a trickle and significantly increase cycle time.
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