Thermoforming difficult materials

Many new developments are taking place in the thermoforming sector that today’s plastics producers need to take notice of in order to support their bid for more efficient production. In this aspect, ILLIG has provided its own share of innovations and these were very much apparent during the K 2013 fair.

The company’s exhibits featured an IC-RDKP 72 with a maximum forming area of 756mm x 535mm which was shown making sophisticated hinged packs of polypropylene (PP). Using a six-cavity mould, the machine runs at over 30 cycles per minute. PP is a difficult material to process. It poses particularly exacting demands on process control due to its semi-crystalline material structure, requiring a careful balancing of parameters in all phases, from heating up the material band to de-moulding of the thermoformed products.

Experience shows that a skilled set-up operator can get approx. 24 cycles per minute out of this technology when forming parts of uniform quality with appropriate repeatability. Equipped with ILLIG’s “IC - Intelligent Control Concept”, the same thermoforming line yields 25% enhanced productivity, even without any particular expertise on the set-up operator’s part. This translates into an additional yield of around 2,100 more marketable trays per hour.

RDKP type thermoformers are roll-fed vacuum and pressure forming machines with separate forming and punching stations. They are employed specifically for making trays and hinged packs of thermoplastic film, mainly of the type used to protect food in transit and on supermarket shelves. Flexible medium-sized and even small production runs – with the attendant frequent changes of material, formats and molds – are common in day-to-day industrial practice. From this perspective, RDKP and RDK thermoforming machines (the latter featuring a combined forming and punching station) benefit substantially from the “dynamic process optimisation”, “faster mould change” and “compensation of ambient influences” modules forming part of the IC modular system.

Dynamic real-time optimisation

The productivity of the thermoforming machine can be leveraged most effectively by means of the “dynamic process optimisation” IC module. It relies on a motion control system, not just to coordinate the machine’s operating sequences but also to match all movements harmoniously within the entire production line. Moreover, parallel movements can thus be optimised wherever they occur and can be utilised to reduce cycle times. It is this automatic optimisation process built into IC machines to which the IC-RDKP 72 shown forming hinged PP packs at K 2013 owes its high productivity increase of approximately 25% over a manually set machine. The experience of packaging producers in day-to-day operating practice has shown that with amorphous thermoplastics, which are markedly easier to process than PP, productivity gains of as much as 40% are achievable.

Moreover, due to its harmoniously matched movements, an IC machine runs notably more quietly than an equivalent servomotor-driven machine without IC capabilities. Harmonious motion sequences also reduce wear, not just of the thermoforming machine but also at downstream stations. Thus, the service life of the self-centering steel rule punch press is substantially enhanced in PP thermoforming with an IC-RDKP7.

More reliable mould and material changes

The “faster mould change” IC module not merely savAir Max 90 Check In