Explanation of the Plastic Pipe Extrusion process and why cooling is required.
The extruder takes the raw plastic material in either pellet or powder format and is heated and forced through a forming die in the shape of a pipe or profile such as window frames
The cooling is achieved by either an initial bath or spay booth with cooling water to ensure it takes on its correct shape
If the Pipe or profile is likely to lose its form either because of its intricacy or weight the first stage will be a vacuum bath which has a vacuum pump together with a cooling spray bath to ensure that the product stays in shape
Pullers pull the material (gently) through the process where it meets a winding machine ready for packing as the finished product
Product examples: Plastic pipe, window frames or plastic casing on cables.
Water return is normally by gravity or pumped via sump pumps below the machines so care must be taken as flow might be cyclic.
The cooling water is used directly on the process and therefore might be contaminated, the two options are to have an intermediate heat exchanger between the cooling plant and process or a filtration system such as a spin clean however this only filters to 10 micron and therefore could still contaminate the chiller system.
Plastic Pipe Extrusion Cooling Systems
Why is cooling required for the pipe extrusion cooling process?
The purpose of the cooling tank is to cool the plastic from a soft state to a hard state. To achieve this it removes the heat by transferring into the water directly from the product. A cooling system is required to remove the heat from the water tank but because the cooling water is in direct contact with the product and therefore either swarf from the finished product or even the raw product can get into the water. A heat exchanger or sophisticated filter system must be used between the cooling baths and the chiller system
As already stated with profile or larger pipe extrusion the shape might collapse before being cooled and therefore it will go through a vacuum cooling bath before the normal cooling bath to ensure that the shape is maintained. The vacuum is created by a normal water pump sucking from the chamber but it operates extremely inefficiently and therefore the total power must be included in the load calculations
How The Cooling Is Calculated
Tools = Plastic through put x Plastic Factor = Cooling Duty in KW
Vacuum pump kW = cooling duty in kW
Aqua Are Here To Help
Our engineers are experienced in the plastics industry and are ready to help, should you require pipe extrusion cooling.
Please try and answer the following questions as thoroughly as possible as the more information you can provide our engineers, the easier it will be for us to help you with your requirements:
What is the temperature of the chilled water required?
What water pressure do you require at the tools?
What is your plastic throughput/hour?
What type of plastic is being used?
What is the in/out differential?
What is the method of water return?
What is the vacuum pump size?
Call us today on 0333 004 4433 to speak to our engineers. We look forward to speaking to you soon and helping you with your plastic pipe extrusion cooling requirements!