“Many industries have now realised that implementing sustainability goals is not just a ‘must’, but actually pays off for individual companies,” says Patrick Hermann, Head of Design and Development at Kraus Maschinenbau. “In the medical and pharmaceutical industries, however, this process is progressing slowly – even though there is so much potential, especially in terms of waste reduction.” With numerous medical products such as sterile packaging, blood bags or flexible components like tubing, plastic is often unavoidable. In the case of less critical applications, however, the situation is different: many components such as outer packaging or inlays can easily be made from paper or cardboard, which place significantly less strain on the environment during production and disposal.

But why has this so rarely been the case in practice so far? Hermann has an answer ready: “Cardboard packaging has so far been more expensive to produce because folding and shaping require more complex work steps, and most companies first have to invest in new systems for this.” However, in recent years, Kraus Maschinenbau has observed an increasing demand for exactly this. Many manufacturers are interested in producing conventional trays for medical products such as medicines, ampoules and syringes from cardboard at low cost. Therefore, the machine manufacturer began developing initial concepts for the new cardboard tray former in 2020.

Patented assembly for separating, folding and combining

The cardboard tray former consists of four segments: at the beginning, there is a feeder for the still-flat cardboard blanks that form the supporting frame of the trays. These pass through a gluing station before cut-outs for the recesses are inserted, folded and placed into the supporting frame in another feeder. The finished trays are then stacked for removal or, as needed, transferred to downstream systems for filling with products. The entire process is fully automated. “The complex unit for separating, folding and combining the individual cardboard components is a completely new design that we have already applied for a patent for,” adds Hermann.

However, to ensure that the entire line, measuring approximately 6,400 x 2,800 mm, was not too large, the new development required particularly sophisticated pneumatics. For this, Kraus Maschinenbau turned to its long-standing business partner Konstandin. “The challenge was not to cobble together a complex assembly from several components, but to design it from scratch as a single unit to meet the strict requirements,” explains Mathias Kraft, Technical Manager at Konstandin. “Among other things, it had to be as light and compact as possible, have a low centre of gravity and allow for movement in several directions as well as stops.”

Compact pneumatics with extra damping

The first hurdle Konstandin had to overcome with the gripping and folding unit was to make the cylinder housing as small as possible. With the required stroke length of 120 mm, the entire structure would have been far too large, necessitating a redesign of the system and inevitably requiring more space and increased material costs. “However, we divided the stroke into two 60 mm movements so that it moves one step upwards and one step downwards lengthwise,” reports Kraft. “This allowed the housing to be built half as large.” A cam disc was also used to realise not only the double-acting longitudinal stroke but also a transverse stroke, which is responsible for clamping and folding the cardboard. To prevent the components for the transverse stroke from moving on their own due to rotation, the cylinder operates with particularly low back pressure.

The rapid cycle times required by Kraus Maschinenbau also presented the developers with challenges. A cycle should not exceed approximately one second. For the pick-up movement, this consists of extending, suction, retracting and rotating by 120 degrees; the placement movement involves clamping, extending, retracting and rotating. However, due to the high speeds when reaching the end positions, impacts occur that inevitably place heavy stress on the components. To increase the durability of the components nonetheless, the strong forces are absorbed by special damping discs. Additionally, the screw connections were specifically secured against unintentional loosening.

A step towards greater sustainability

In addition to the gripping and folding unit, Konstandin supplied special rotary unions for the new system, which provide the system with compressed air for movement, vacuum for the suction device and electricity for the piston end-position switches. Due to their modular design, the rotary unions are equipped with a leakage channel, which allows seal wear to be monitored using sensors. “This makes it possible to plan maintenance in the long term,” explains Kraft. “At the same time, there are no unpleasant surprises with the media supply that could impair operations.”

The development process for the complex assembly took only two months. Thanks to the smooth collaboration with Konstandin, Kraus Maschinenbau was finally able to present the new cardboard tray former for the first time at Pharmintech in Milan in spring 2022. “The feedback was consistently positive,” recalls Hermann. “There is undoubtedly strong demand for sustainable packaging that is in no way inferior to conventional plastic moulded parts in terms of performance. With the cardboard tray former, we are now offering companies the right tool for this.”

Further information at https://www.krausmb.de/ and https://konstandin.com/.