Durable and economical bearings for format adjustment in tray inserter

Plastic trays are the most common solution in supermarkets for the cost-effective storage of meat, fish, fruit and vegetables so that they remain fresh. In approximately 50% of plastic trays, there are so-called absorption pads that protect the product against pressure and absorb and bind any fruit juice that escapes (see Fig. 1 below).
In 2005, LAD GmbH developed an absorbent pad insertion machine which ensures that the pads are cut to the right size and placed in the packaging so that they cannot slide about; this machine is now sold worldwide. The system is fast and efficient, whereby one machine can make up 100,000 trays in eight hours.
The absorption pad insertion machine is designed for operation by one worker and is built in a U shape so that the travels are short. But how is an absorbent pad placed in a tray in the shortest of times?
First, the employee must fill a rack with the trays. From there, the trays are transferred into the automated system, where they are "de-nested", i.e. separated, the nonwoven is cut to size, then inserted and welded or glued in place with the aid of a two-point ultrasonic technique. Afterwards, a quality check based on camera technology is carried out. If the tray passes the check, it is "re-nested" again, i.e. the trays are stacked inside each other, after which they are ejected. The employee can now remove and pack the stacked trays. In just one minute, 200 trays can be made up.
However, as there are many different packaging sizes on the market, it must be possible to easily reconfigure the machines at least once a day. Both for de-nesting and cutting the nonwoven to size, as well as for re-nesting, format adjustment is necessary for every tray. To achieve this, the machine manufacturer needs safe, durable and cost-effective automation solutions.

LAD GmbH can freely select from a large variety of different lead screws, materials and glides from the modular drylin SHT linear system. They can be individually configured online in the free drylin SHT designer. The SHT linear modules enable completely lubrication and maintenance-free movement with a high degree of precision.

Adjustment of the tray rack
At the beginning of the process, classic plain bearing technology comes into play in the system. To adapt the rack for the trays, drylin R bearings made of iglidur J are used. They provide lubrication-free bearing support on the stainless steel shaft.

De-nesting of the absorption pads
A drylin SHT linear system made of hard-anodized aluminium with a reverse lead screw is used for adjustment of the de-nester's format (Fig. 2). This is easy to adjust by means of a hand wheel. The carriages of the linear system move over liners made of iglidur J tribo-polymers, which are lubrication-free and highly wear-resistant.

Format adjustment of the absorption pads
We also offer cost-effective solutions for lighter tasks such as adjustment of the absorption pad width. A durable and attractively priced linear bearing is used: The drylin SHT module as a low-cost variant made of plastic (Fig. 3).

Re-nesting and ejection of the plastic trays
A special solution was needed for vertical stacking and automatic ejection of the stacked trays: Two SHT linear modules made of aluminium that are connected via a toothed belt are used for this today. The ejection pusher is driven by drylin NEMA stepper motors (Fig. 4), while the D1 dryve enables simple, cost-effective control (Fig. 5). The control system is suitable for all stepper, DC and EC/BLDC motors and can be operated without software via the web browser from a PC, smartphone or tablet without an Internet connection.