Whether fruit, yogurt or cookies - you come across many products in the supermarket whose packaging has been produced using the thermoforming process. Thermoforming is a widely used process for the production of plastic-based packaging, as it has major advantages over other methods of plastic processing: Investment costs in equipment and tools are low and output is high due to short molding cycles. Thermoforming also enables efficient use of materials and reduces the weight of packaging.

The goal: sustainable plastics processing

Illig Maschinenbau specializes in the development and manufacture of thermoforming systems. The company began manufacturing machines in 1956; four years later, Illig introduced the world's first roll-fed vacuum forming machine, the R 650. Today, Illig is one of the world's leading manufacturers of thermoforming systems. In addition to the usual semi-finished products made of polyethylene terephthalate (PET), polystyrene (PS) and polypropylene (PP), the thermoformers can also process bioplastics and recyclates.

Illig is committed to the resource-saving production of plastic packaging and recently became a member of the R-Cycle community. This enables the company to advise its customers on the introduction of digital product passports. These store material properties that are relevant to recycling so that pure fractions can be formed when plastic packaging is recycled. This significantly increases the quality of the recyclate.

Rack and pinion gearboxes assume central function

The RDF 85 roll forming machine from Iillig can produce trays up to a size of 800 x 600 millimetres. © ILLIG Mechanical Engineering

Illig installs numerous high-quality components in its thermoforming systems - including rack and pinion gears from Leantechnik. The gearboxes are used in the RDF 85 air forming machine, which can produce trays, trays, lids, blister packs and cookie inserts. In the machine, the gearboxes move the pre-stretcher and the clamping frame, which each perform an important task in the production process: The stenter frame clamps the film to be processed in the area where the forming is to take place. This prevents material from flowing in an uncontrolled manner and impairing the forming process. The pre-stretcher then mechanically pre-stretches the heated plastic before the final shaping is carried out using compressed air. In this way, the desired contour of the deep-drawn part is roughly predefined and the wall thickness distribution of the molded part can also be controlled.

High demands on the components

The IC-STAL 90 die cutter is used to cut formed film tapes. © ILLIG Mechanical Engineering

Illig relies on rack and pinion gearboxes from Leantechnik to drive prestretchers and stenter frames because they meet the high requirements of the application. The user not only expects a service life of at least 20,000 operating hours and customer-friendly maintenance intervals from the rack and pinion gearboxes, but also flexible assembly.

Two lean-SL 5.3 gearboxes with a hardened gear rack are installed in each RDF 85 air forming machine. The lean-SL series was specially developed for simple synchronous positioning tasks where a guide is already present and no lateral forces need to be absorbed. Lean-SL rack and pinion gearboxes are available in different sizes and in three variants, can absorb lifting forces of 800 to 25,000 newtons and achieve lifting speeds of 0.6 meters per second. The gearboxes are available in a standard version, as a lean SL double with two racks for applications with gripping, closing and centering movements and as a particularly compact lean SL 5.m for applications with very small installation spaces.

Powerful gearboxes required

Leantechnik offers machine builders a wide range of rack and pinion gearboxes that can be combined with each other as required. © LEANTECHNIK

Rack and pinion gears are not only part of the RDF 85 thermoforming system - they also perform reliably in the IC-STAL 90 horizontal die cutter. The process-controlled punch is used to subsequently cut out formed film strips that were previously produced by Illig automatic rollers. A rack-and-pinion drive on the so-called ejector drive of the punching machine pushes the formed parts out of the punching tool. Product stacks are formed by varying the stroke lengths. As the systems work with a cycle frequency of up to 165 strokes per minute, the demands on the performance of the gearboxes were also high.

Leantechnik also manufactures rack and pinion gearboxes in special designs on request. © LEANTECHNIK

Illig chose a lifgo 5.1 rack and pinion gearbox for the pusher drive. The gearboxes in this series are equipped with a quadruple roller guide with high positioning and repeat accuracy. Leantechnik supplies the gearboxes in various sizes and, on request, also in customized versions for special requirements. The rack and pinion gearboxes are manufactured in modular design and can therefore be combined with each other as required. The gearboxes can be used to implement a wide range of handling and positioning systems.