You can see the results of plastic tubing extrusion around us everywhere. Things like sweeper parts, parking meter covers, and rail covers are just a few of the applications. There are all different shapes, sizes and colors of plastic tubing, and even hundreds of grades. Plastic tubing can be designed for a wide variety of applications in many markets, including medical, chemical processing, industrial, retail, packaging, hardware, and food and beverage.
The procedure for plastic extrusion is a high volume manufacturing process where raw plastic material is melted and shaped into a continuous profile. The extrusion process produces end products like pipe/tubing, weather stripping, fence, deck railing, window frames, adhesive tape and wire insulation. During this process, raw thermoplastic material in the form of small beads, typically called resin, fed from a top mounted hopper into the barrel of the extruder.
The material then enters through an opening near the rear of the barrel and comes into contact with the screw. The rotating screw forces the plastic beads forward into the barrel which is heated to the desired melt temperature of the molten plastic. Usually this temperature can range from 392 °F to 527 °F depending on the type of polymer. In most cases, a heating profile is set for the barrel in which three or more independent PID controlled heater zones gradually increase the temperature of the barrel from the rear to the front. This allows the plastic beads to melt gradually as they are pushed through the barrel and lowers the risk of overheating which may destroy the polymer.
Extruded tubing process, such as drinking straws and medical tubing, is manufactured the same as a regular extrusion process up until the die. Hollow sections are usually extruded by placing a pin or mandrel inside of the die, and in most cases positive pressure is applied to the internal cavities through the pin. Tubing with multiple holes or lumens must be made for specialty applications. For these applications, the tooling is made by placing more than one pin in the center of the die, to produce the number of lumens necessary. In most cases, these pins are supplied with air pressure from different sources. In this way, the individual lumen sizes can be adjusted by adjusting the pressure to the individual pins.
Most people never stop to think all the things that touch their lives that have been made from plastic tubing. The plastic tubing extrusion process can produce everything from the straw that you drink your milkshake with to the large rod pole that rolls out your porch or camper awning. Plastic tubing extrusion products are all around us every day. We touch them, we use them, and they make our lives better. For more info about plastic extrusions you can visit the link.