Illig Maschinenbau, a global manufacturer of machinery and tools for the thermoforming and packaging technology, presented two major examples of applications demonstrating improved productivity using its Intelligent Control (IC) concept. The exhibits on the stand were an IC-RDKP 72 and IC-RDM 54 K.
Illig booth at K 2013
The IC-RDKP 72, which has a maximum forming area of 756mm x 535mm, was tasked with making sophisticated hinged polypropylene (PP). PP poses particularly high demands on process control because of its semicrystalline material structure and requires a careful balancing of parameters in all phases, from material heating through to de-moulding of the thermoformed products. The Illig machine runs at over 30 cycles/minute with a six-cavity mould, which is 25% better than the normal 24 cycles/minute output level that a skilled set-up operator would be expected to achieve, when forming parts of uniform quality with appropriate repeatability. The improvement with Illig’s IC fitted translates into an additional yield of around 2,100 more marketable trays per hour.
An IC-RDKP 72 roll-fed automatic thermoforming machine equipped with the new Illig IC control technology (photo: Illig)
RDKP type thermoformers are roll-fed vacuum and pressure forming machines with separate forming and punching stations. They are used specifically for making trays and hinged packs of thermoplastic film, which are used to protect food in transit and on shelves. Medium and even small production runs – with the attendant frequent changes of material, formats and moulds – are common in day-to-day operations.
Hinged pack made of PP on an Illig IC-RDKP 72 and APET cup made on an Illig IC-RDM 54K (photo: Illig)
Automatic and dynamic real-time process optimization …
Illig says that productivity of thermoforming machines can be leveraged most effectively by means of the “dynamic process optimization” IC module, which relies on a motion control system both to coordinate the machine’s operating sequences and to harmonise all movements across the entire production line. Parallel movements can be optimised wherever they occur and used to reduce cycle times. It is this automatic optimisation process, built into IC machines, to which the IC-RDKP 72 on the stand at K 2013 owed its productivity advantage over a manually set machine. Illig claims that even greater gains are possible, with packaging producers using amorphous thermoplastics, which are easier to process than PP, experiencing output levels up to 40% higher.
Illig further asserts that IC-equipped machines are quieter than manual equivalent servomotor-driven machines and that harmonised motion reduces wear and extends the life of the self-centring steel rule punch press.
… plus safer and more reliable mould and material changes
The “faster mould change” IC module not merely saves time but also makes for a safer and more reliable change of tooling, Illig says. During changeovers, the operator is given specific on-screen guidance about all activities necessary for a mould change along the entire thermoforming line. Where product changes are frequent, the “compensation of ambient influences” IC module corrects the temperature drift of the material band via a continuous, automatic adjustment of the heating element temperature or heating time, respectively, and by taking into account the rise in machine frame temperature as production continues.
Big cup savings
Also on the stand was an IC-RDM 54K with a forming area of 520mm x 300mm, which was shown making amorph polyethylene terephthalate (APET) cups in an 18-cavity mould at 50 cycles/min, which adds up to 54,000 cups/h. RDM-K machines, which are specifically designed for volume production of cups in various shapes and sizes from thermoplastic film, are often deployed in-line; for example, co-operating with an upstream film extruder. Such configurations include high-volume manufacturing of yoghurt cups, made in millions of units. The IC’s “ThermoLineControl”, “Illig NetService” and self-adaptive start-up (“sas-up”) modules are re-designed to safeguard the high productivity and availability rates required in high-volume applications and help users to save costs.
An IC-RDM 54K roll-fed automatic thermoforming machine equipped with the new Illig IC control technology (photo: Illig)
The ThermoLineControl module provides central management, control and optimisation of the entire thermoforming line from the forming station. A prerequisite for its use is that each individual machine is equipped with a Profibus interface, which makes the system more operator-friendly and saves time during a mould or format change. Where an RDM-K machine operates in-line, production downtimes must be minimised in the event of a malfunction and it would take far too long to call out a technician. The ThermoLineControl module is claimed to make fault analyses and troubleshooting easier and more effective and thus help to ensure improved uptime. When used in conjunction with Illig NetService support, technicians can review all system components via the internet and carry out diagnostics and troubleshooting while making rapid corrections where malfunctions are due to equipment settings.
At this year’s K, the IC-RDM 54K system demonstrated its performance potential by producing approximately 54,000 APET cups per hour (left). The new Illig IC control concept includes compatible modules suitable for dynamic optimisation of a thermoforming line’s processes.(photos: Illig)
The new sas-up IC module lets the RDM-K get into its stride at a reduced cycle rate and with process-optimised settings, thus minimising start-up. Illig says that launching the thermoformer at 15 cycles/min, rather than the 50 of production mode, saves 70% of the film volume that was previously lost in the initial phase. If it takes, for instance, an hour to start up a mould, sas-up thus saves over a kilometre of film length. Switching from the self-optimised start-up operation to production mode automatically switches production to a high cycle rate and matching heater output.
Speed and high precision
Additional new technological features of the current servomotor-driven RDM-K type machines include a reduced input of forming air and a new downholder pressure control system, which adapts the pressure level to the relevant thermoforming process phase. Illig maintains that the reduced air volume ensures a fast forming cycle and improved contour definition in each cavity. The downholder pressure level control system prevents the formation of the previously inevitable bead along the top edge. This material portion, accounting for around 10% of the product weight, is now drawn into the side wall as the cup is formed, thereby adding to its stiffness. Illig says that these and other new features of the RDM-K line-up has enabled a large foodstuffs group to reduce the weight of its previously injection-moulded yoghurt cups by around 20% while still meeting the stiffness specification in a reliable manner.
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