Format change detection with RFID

The quality requirements of globally leading manufacturers of premium chocolate include not only raw materials and manufacturing processes but also product packaging.

Perfectly packaged chocolate bars without a single defect are essential. Frequent format changeovers are a particular challenge. LoeschPack has met this challenge elegantly with their newest version of the two-stage version of the LTM-DUO fold wrapping machine. This relies on format changeover parts with a fixed stop and proven Balluff RFID for automatic interchangeable part detection.

The benefit goes to the user, who profits from extremely short setup times and significantly improved machine flexibility in format changeover. Christoph Krombholz, Marketing Manager at LoeschPack: “The packaging machine doesn’t start until all the components are in their correct location. This precludes misplacements.” 

The LTM-DUO two-stage fold wrapping machine is designed specifically for chocolate bars. This high-tech equipment is always the first choice, especially when high flexibility is needed with respect to the packaging type, materials or packaging sizes together with high performance requirements. It offers outstanding product quality and provides special product protection when desired in the form of tightly sealed packages. The system concept with its strict separation of drive and product-feeding sections guarantees a high degree of hygiene with good accessibility for operation, cleaning and maintenance.

A particular challenge is the variety of movements within the system. LoeschPack relies on a combination of mechanically, cam-controlled drives using a central main shaft and servo-driven movements. The main shaft with central lubrication features hardened, machine-specific cams with specially calculated profiles. This ensures that all movements and assemblies remain coupled – positively driven and strictly coordinated.  “Their use is always needed,” notes Krombholz, “where many complex and identical movements are present and high fail-safe operation over many decades is required. This applies to our equipment because an average of 90 percent of the machines are destined for worldwide export.”

Fast format changes are a necessity for getting maximum utilization and flexibility out of the equipment. LoeschPack has decided on format parts with fixed stop, since these allow adjustments for new recipes, bar sizes and materials to be made. “No special technical knowledge is required,” notes Christoph Krombholz. “An open-end wrench is the only tool the operator needs to replace and tighten down a component in just a few minutes without having to call in an installer. This saves time and guarantees high process quality.”

The BIS U high-frequency industrial RFID system from Balluff ensures that the interchangeable parts are automatically detected and identified. Instead of metal labels for identifying the parts, RFID data carriers are used whose identity is read without contact and therefore wear-free by a UHF read/write head. “This works even when there is no line of sight and/or the labels are dirty,” explains Industry Manager Christine Rühling from Balluff. The main components of the BIS U industrial RFID system consist of the processor unit, one or more UHF directional antennas with circular polarization, and the already mentioned transponders for object identification.

The machine controller automatically evaluates the information, correspondingly initiates stored actions and thereby actively supports the user. An LED indicator light with IO-Link interface, the Balluff SmartLight, changes colour to visualise progress when change outs are made and can be seen even from a great distance. For this it offers a wide range of colours with freely selectable light intensity. The system only starts up when all the interchangeable parts are placed and fixed at the proper location. This eliminates machine damaged caused by startup with incorrect parts.

“The special feature of the SmartLight,” notes Ruhling, “is that it can be flexibly adapted to virtually any requirement from the controller without cumbersome hardware configuration. At the same time, linking to the controller through an IO-Link master opens up many typical IO-Link advantages.”

The Balluff UHF system can be seamlessly integrated into the system design. The compact data carriers with dimensions of 7.1 x 3.1 x 13.1 mm are absolutely flat and can be attached to the format parts without protruding. Since they bear a serial number fixed in memory, the so-called UID code (Unique Identification), the format parts can be identified unambiguously at any time, even when the transponders are attached to metal surfaces. This was also one of the essential requirements of LoeschPack.

The passive data carriers require no power supply of their own, since they get their energy from the UHF read/write head. This makes batteries unnecessary. The electronics and antenna are integrated into the tag. Together with the passive tags, the UHF solution offers ranges of up to 6 metres and high capture reliability. The system is capable of bulk capture, so that all the interchangeable parts in the range of an antenna can be read efficiently regardless of their spatial orientation.