Types of Plastic Extrusions
There are wet and dry types of plastic extrusions. However with pressurizing, a wide range of intermittent and continuous extrusions processes are also available.
With profile extrusion, different parts and products to including tubing used in the medical profession to straws for sipping beverages are made. A mandrel or pin is placed inside the die that makes it possible for hollow sections to be extruded. Then to internal cavities positive pressure is usually applied via the pin.
For tubing made with multiple holes, special tooling is required. For this, more than one pin is placed in the center of the die, which in turn creates the number of holes specified. Typically, air pressure from different sources is supplied to the pins for this, which makes it possible to adjust the size of the holes when pressure to individual pins is changed.
Another method used for plastic extrusions is called co-extrusion. This involves multiple layers of material being extruded at the same time. For this, at least two extruders are used to melt the plastic, which ensures the volume of throughput for different resins going to a single die is steady. The outcome is extruded resin in the exact shape wanted. For the layer of thickness, this is controlled by using the sizes of individual extruders that deliver the material and relative speeds.
Co-extrusion is sometimes the better solution compared to a single layer extrusion process. For instance, within the industry of vinyl fence making, several layers of material are tailored according to the environment. In most cases, the process entails a thin layer of compound made with high-end additives that resist weather are extruded on the exterior of the fence. Then for the interior, the compound focuses more on structural performance and impact resistance.
Excursion coating is also part of the plastic extrusion process. The ultimate goal is for an extra layer to be blown or cast filmed onto an existing roll of paper, film, or foil. As an example, to make paper more water resistant, extrusion coating works great to improve the paper's characteristics.
In addition to the above-mentioned plastic extrusions are others such as sheet/film extrusion, compound extrusion, blown film extrusion, and more recently, 3D printer filament extrusion.Back to Blog ...