To keep screws from overheating when manufacturing plastics, it is necessary to implement a cooling tower. How these towers can be implemented, fortunately, can easily be controlled by the manufacturer, since there are many options available to engineers.
How Screw Cooling Works
Screw cooling should always be installed on the feed section of a screw. The easiest way to implement screw cooling is with a water tower. The flow can simply be controlled so that the return water out of the screw is maintained. The water tower should be used to maintain a temperature range of 100 degrees Fahrenheit to 120 degrees. The water tower system should have a shut-off valve and immersion thermometer implemented.
Cooling With Water
The water tower, also known as the chiller, is designed to move heat to and from the system. Ideally, the heat that is extracted using the water tower system should be recycled for other purposes, but it can be exhausted into the ambient air. The water tower can be centralized, where a single chiller is used to meet the needs of several units. Or, each chiller could be installed to work with a specific unit. The decentralized chillers are much smaller in size.
Cooling With Air
While chilling screws with water is the best approach, sometimes it is not practical depending on the application. Under this situation, it is better to use air chilled or oil chilled cooling towers. Oil-chilled cooling towers use any type of oil that remains a liquid at a temperature that is below the ambient temperature. Air-chilled cooling towers rely on fans and may use conditioned air to lower the temperature of the cooling screws. However, air-chilled units can also be cooled simply using the surrounding air.
The downside of chilling screws with air is that air is not able to lower temperatures as rapidly as water. When water comes in contact with a hot screw, it removes heat by evaporating. With air-powered chillers, the air absorbs heat from the screws, but the amount of heat that can be absorbed by the air isn't as great as the heat that can be absorbed by water.
Screw Cooling Is Great For Plastics Manufacturing
Fortunately, implementing screw cooling will usually be a benefit to the system. The resin needs to slip on the screw. Cooling the screw reduces the coefficient of friction between the screw and the plastic pellet. Therefore, you should talk with your engineer about how water towers can be used to cool screws in your system.
Talk to a company like AUSTIN MAC INC for more information.