Extrusion blow-molding of large hollow plastic bodies

Since the mid-90s, the extrusion blow-molding of large hollow bodies has undergone spectacular growth, notably with the emergence of plastic fuel tanks. These are gradually replacing metal tanks: in 2010, almost 50 million plastic parts were produced worldwide. The market share of plastic fuel tanks is around 90% in Europe, 85% in North America and 50% in Asia, where the switch to plastic fuel tanks took place later, but where strong growth is expected by 2020.

The success of plastic fuel tanks with carmakers is based on both technical and economic arguments. The plastic solution saves weight, and offers the advantage of more complex designs better able to integrate into the vehicle environment. It also offers improved safety in crash and fire tests. The high chemical inertness of the plastics used means that the effects of corrosion can be avoided, whether on the outside (environment, road salt) or the inside (biofuels) of metal tanks. Finally, there are ways of ensuring recycling in the same application.

After a brief review of the manufacturing process, this article describes the specific features of blow-molding large hollow bodies, in terms of the materials used, equipment and tooling.