Extrusion of Thermoplastic Profiles and Edges: The basic concepts

It’s difficult to talk about this matter without getting technical. On one hand if I tried to be really technical, I’d be risk sounding ridiculous and infuriating mechanical engineers with inaccuracy, on the other hand I also would risk being the only one to read what I’m writing because it is too academic. Therefore I reckon it’s better to fly low so that everyone can understand me.

First of all I must point out that we are in the field of extrusion, one of the oldest production process but which is still very current. As you know, Gildo Profilati is specialised on the extrusion and co-extrusion of thermoplastic materials. Extrusion is based on a very simple theoretical concept but it’s a very complex operation in its production phase, to produce a high quality product. Polymeric material, in powder or grains is fed into the mechanical installation called the extruder through an opening called Hopper. This polymeric material is softened and melted through the pressure exerted by a screw inside the extruder, and then forced toward the exit to the extruder head. The die, the tool which gives the material its final shape, is applied where the material, which is usually incandescent comes out of the machine. This product is immediately cooled with water or air and is then cut into bars if it is rigid, or wound around reels if it is softer.

Shall we simplify it even further? Do you remember your mother making homemade pasta? The concept is the same. A dough is forced through the tool which expels flat sheets that will then be cut into smaller sections when it comes out: noodles.

Let’s go into more detail and try to clarify the terminology which is often misused, referring to the product obtained by extrusion.

Plastic extruded profiles are products with a constant section.

The interior can be solid or hollow and can have various outlines depending on the exit hole of the dye,  which has previously been designed.

There are infinitive fields where you can apply plastic moulding or edges. Extruded profiles are everywhere in our daily life. Just to give one example, in the medical field, the tubes are used for drips and transfusion are obtained through extrusion, as hose pipes are used in gardening.

On the other hand, edge is the name of the decorative or structural extruded profile used to rim a surface or its corners. Let’s see some applications. In the car industry, the side bumpers on the doors are often adhesive extruded edges. In interior design angular extruded edges are used a lot to decorate and protect the edges of walls. In the furniture field there is a particular type of edgebandings in ABS and PVC or aluminium, used to rim the sides of the panels to make wardrobe doors and the doors on kitchen cupboards. The application of this particular type of edgebandings is obtained through special machines which apply the edge to the panel using pressure and gluing it in place with a primer applied to the edging and a hot-melted glue applied by the edgebanding machine.

I hope this has been useful and in the near future I will go into more detail about the technical aspects, hoping not to stretch your patience.

Franco Bandelli