Automatic Cardboard Box Handling Without Barcodes?

One aim of the control system for automatic cardboard box conveyor systems is to be able to perfectly identify boxes at every point in the system. In deep-freeze warehouses, however, the normal identification methods such as barcodes or RFID chips have major disadvantages.

The first experiments with the bar code technology were made in 1949

For tracking cartons it is normally necessary for them to be uniquely identifiable. The use of barcodes in fully automated deep-frozen areas is particularly difficult if for reasons of internal organisation the barcodes can only be applied in the refrigerated area and cannot be applied to the boxes at normal temperature. It must, however, be possible for the frozen cheese, cooked meats and ready-made pizzas to be identified and located in the warehouse area, not least so that consumers receive what they have actually purchased.

Too Cold for Adhesives and Ink…

Even for labels, the conditions in the deep-freeze warehouse are extreme. It is not unusual for temperatures here to remain permanently below -30°C. This places corresponding requirements on the mechanism for attaching the labels. The minus temperatures in the deep-freeze store are not suitable for attaching labels directly. At such temperatures, the adhesive on the label foil cannot harden sufficiently and therefore does not satisfactorily bind to the backing. The labels do not stick on adequately, if at all.

Directly spraying the code onto the box using an ink-jet printer is also made more difficult by the low temperature, as the oil and alcohol-based inks lose their fluidity at extreme minus temperatures and the printer nozzles become blocked. Despite years of testing, no satisfactory result has yet been achieved in this area.

Even reading a barcode applied at an earlier stage is only possible using an expensive barcode reader with its own heater.

…and Too Expensive for RFID

RFID marking, on the other hand, by which data are transferred using radio waves without contact or visual contact, is certainly technically feasible, but is generally excluded on economic grounds (high costs for the memory chips times high number of single-use boxes). This technology has therefore so far only be used in individual cases in the deep-freeze area for pallet warehouses with their own system pallets.

Work is permanently ongoing on lower-cost RFID tags, and as soon as their costs can be levelled out to the same cost as bar coding or just slightly higher, RFID identification will probably replace the barcode eventually in material flow tracking.

Expectations of Material Flow Tracking

Manual picking at -28° C

• Consistent traceability of products through batch and sell-by date management, keeping to pre-set sell-by date limits
• Linked in to an automatic (cardboard box) warehouse
• Advance notice of warehousing requirements and booking of warehouse spaces from I-point
• Paperless order-picking control system
• Status report when dispatch targets reached
• Minimized process costs

Despite the sometimes enormous volumes up to 3000 boxes per hour, the above costs lead to considerations on the part of suppliers of conveyor systems, of controlling the cardboard boxes even within highly complex systems more or less exclusively through “tracking” with “virtual” packing numbers allocated internally in the control system and also only used internally for control purposes without further communication on the line.

This method has in some cases already been used for some time in comparatively “slow” accumulating conveyors in pallet conveyor systems, but is only now being used for the first time in high-performance installations and for other types of conveyors (e.g. belt conveyors). However, this method also has its advantages and disadvantages:

Pros and Cons of Container Tracking Without Barcode

Outlook

If we compare the advantages with the disadvantages it becomes apparent that relative to particular process parameters, tracking boxes without barcodes is inevitable. This raises the reliability of the process and is not affected by extreme temperatures ranges.

However, this reliability is generally bought at the price of higher initial investment and higher sensitivity in the systems.

The development of adhesives, and particularly of inks, is moving forward permanently, so that in a few years probably safer alternatives to tracking without barcodes will be feasible. Firms are constantly presenting alleged solutions, which hardly, however, prove their worth in practice.

As soon as the RFID technology can be used at sensible economic cost, it will most probably supplant all other solutions.