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Moisture on Injection Mold

This is a matter of physics. Moisture is caused by temperature and humidity differentials. If the air around the injection mold is dry and has the same temperature as the chilled water inside the mold, there will be no sweating. This can be achieved by pumping in dry refrigerated air into injection mold area. But if the water temperature changes, then settings have to be changed. Eisbaer of Austria has a system which passes dried air through a heat exchanger, which use part of the water going into the injection mold. So the air temperature will always be the same as the mold water temperature. Since it does not use an refrigeration, the energy usage is low and it is environment friendly. As for multiple machines, they can also supply a central dryer/heat exchanger, provided all injection molds are running at same water temperatures.

You can try to improve the cooling method using two cooling supply to the injection mold, 1st of supply chilled water into the mold cavity plate, this is to make sure the injection mold temperature are meet the injection processing request, 2nd of cooling is use normal water (the water from cooling tower) supply to the injection mold base so the mold surface temperature will be much more close to the open air temperature will help you to reduce the mold sweating issue. And make sure your injection mold is maintain properly by the schedule, any dirty or rusty will cause to block the air release line in the injection mold, when injection speed build up will cause to air trapping and burn the surface sometime looks like moisture.

Basic facts already outlined well. Multi-cavity molding of PET preforms typically involves huge quantities of cold water (600 liters per minute not unheard of) and extreme turbulence are needed to give the low levels of crystallinity and clarity. Local A/C enclosures are certainly used in environments where condensation would otherwise be a problem.

Another variable is duration of mold-open: the shorter the better, so robotics can certainly help to keep this short and consistent. Insulate exteriors of mold plates where feasible. Consider insulating INSIDE water channels that run through bolsters, where feasible. Bore out to a larger diameter and insert plastic water piping. It really does work.

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