Plastic is a popular raw material in a variety of manufacturing industries because it is cheap and versatile. Many of the products we enjoy today, such as PVC pipes, drinking straws, and window trimmings, wouldn’t be possible without the plastic profile extrusion process. What is profile extrusion?
While you may understand the difference between extrusion and injection molding, you may not realize there are different types of plastic extrusion methods in the plastics sector. Today, we will explain what profile extrusion is and how it varies from sheet and film extrusion.
The Profile Extrusion Process Explained
Profile extrusion is the process of creating continuous shapes of plastic through extrusion. This process does not include forming sheet or film products. The plastic products produced by profile extrusion can be solid (like vinyl siding) or hollow (like drinking straws).
The profile extrusion process resembles the process of other extrusion methods up until the die is introduced. First, raw plastic materials are fed into a hopper and extruder. A rotating screw keeps the plastic resin moving through the heated barrel, which is set to the material’s specific melting temperature. Once the resin is melted, mixed, and filtered, the plastic will be fed into the extrusion die. The die will be placed in cool water to solidify the product. Finally, the die will be moved to the take-off rollers, where the final product is removed from the die.
A pin or mandrel must be placed in the die to make hollow shapes. Then, air should be sent through the center of the product via the pin to ensure the final product maintains its hollow form.
Types of Products Made With the Profile Extrusion Process
The profile extrusion process was invented to produce items of varying shapes easily. Today, this method is used in a wide range of applications, including in the production of medical packaging and residential construction products. Here are just a few of the products made with profile extrusion:
- Plastic Pipe and Tubing
- Vinyl Siding
- Window Frames
- Plastic Fencing
- Automotive Body Side Moldings
- Electrical Conduit and Cable Protectors
- Refrigerator Seals
- Medical Blood and IV Tubing
- Drinking Straws
How Profile Extrusion Differs From Sheet and Blown Film Extrusion
In addition to profile extrusion, there are two other extrusion methods worth noting: sheet/film extrusion and blown film extrusion.
Sheet extrusion is the process of forming plastic sheets or films. Instead of placing the extrusion die in cold water like with profile extrusion, the material is cooled by pulling it through a set of cooling rolls. These rolls also determine the sheet’s thickness and surface texture. Sheet extrusion often precedes the process of thermoforming, which heats the plastic sheet until it is soft enough to be formed into a complex shape.
Blown film extrusion is the process of manufacturing plastic films for products. This process is often used in the creation of shopping bags. The blown film extrusion process resembles that of profile extrusion until the die is introduced. With blown film extrusion, the die is an upright cylinder. The molten plastic is pulled up from the die by nip rollers. The speed of the nip rollers will determine how thick the film is. A cooling ring sits around the die and cools the plastic film as it travels upwards. Once the film is removed from the die, it can be spooled, printed on, or cut into different shapes.
As you can see, the specific die used in the extrusion process largely determines whether a profile extrusion, sheet extrusion, or blown film extrusion method is used.
Plastic Extrusion Equipment to Support Your Profile Extrusion Processes
If you’re interested in incorporating profile extrusion methods into your manufacturing, Plastrac is the company to turn to for essential plastic extrusion equipment. We carry everything from gravimetric blenders to hopper loaders. Contact our team to receive a quote and more information on our products.
