Soffiaggio Tecnica: renewed interest in sequential coextrusion

Last June an official ceremony celebrated the delivery of an ASPI SECO machine to the DuPont European technical centre in Meyrin (Geneva). These recent sales confirm a renewed interest in sequential suction technology, which in previous years had seen a significant decrease when compared with the "boom" in requests for single-material suction technology.

At the end of 2016 two new ASPI SECO machines have been tested prior to delivery to two well-known industrial groups - European and Korean - tier 1 component suppliers to the automotive industry. The first machine will go into production in Turkey, consolidating the presence of ST BLOW MOULDING in one of the most important countries for the production of motor vehicles. The second machine marks a further milestone for the company, being the first ASPI SECO destined for the notoriously fast-growing Indian automotive industry.

Besides having an important local automotive industry, India works as a hub for the major foreign manufacturers thanks to a multiplicity of factors that make investment in India worthwhile (low production costs, flexibility in the labour market, abundance of raw materials, high level of personnel technical qualification, incentives and economic policies, etc.).

The ASPI series blow moulding machines are supplied in the SECO configuration when it is necessary to produce parts with two different materials arranged in sequence. This sequential coextrusion utilises a parison that presents, in an alternating manner, different physical-mechanical characteristics. In this way it is possible to obtain manufactured articles with flexible parts and more rigid sections, thereby avoiding the time and cost of assembling more components. This technology also reduces the product cost, compared to a single-material solution, because each of the two resins is used only in those sections where it is needed.

The two new ASPI SECO machines have the same clamping unit (with maximum opening of 1,400 mm) and identical plasticization units (two 60 mm extruders), but differ in some other characteristics: the clamping forces are 15 and 20 tonnes respectively, and the accumulator head capacities are 1.0 and 1.5 litres.

A peculiarity of both machines - not common on this bi-material typology - is the possibility to reach a process temperature in excess of 350 ° C. This characteristic makes them suitable for processing not only any technical resin available today for blow moulded engine compartment parts, but also new plastic materials that could be developed in the coming years for applications at even higher temperatures: the challenge to metallic materials continues!