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For clean bags and pallets

Optical measuring system for clean pallets
Sensors detect faulty bag valves

If bags aren‘t sealed properly, the product can escape uncontrollably, which can cause entire pallets to become contaminated. Greif-Velox has therefore developed the Valvo Detect system as extension for its bagging machines. Two optical sensors detect irregularities on the bag valves and ensure that the faulty bags are rejected. Valvo Detect is already being used by the ICL Group at their site in Ladenburg.

The damage caused by contaminated pallets can result in annual costs for recalls which hit the five-figure mark. And that’s not all – depending on which product has contaminated the pallets, the consequences can be unpleasant: if it’s bagged chemicals that cause the contamination, this means that the applicable safety regulations are

The ICL Group was also having problems with contaminated pallets. Safety and cleanliness are deciding factors in their industry: ICL is a global manufacturer of mineral-based products used in agriculture and technical materials, as well as in the food industry. At their premises in Ladenburg, Baden-Württemberg (Germany), the Group focuses on developing, producing and distributing additives for paints and coatings for the cosmetics and construction industries, as well as on manufacturing high-quality food additives for the food industry. At this site sodium phosphate is also
packed, a chemical which is used in the food industry as a sequestrant, acidity regulator, melting salt or firming agent, among others.

Damage due to open bag valves

However, when bagging the product, the same problem that affects powder producers across many different industries kept arising time and again: „Some of the bags were not properly sealed,“ explains Thomas Jörder, operations manager at ICL in Ladenburg. „This led to product escaping from the partially open valve.“ This meant that customers from Asia, for example, would send back entire pallets as the bags were contaminated from the outside. Not only did this result in high annual recall costs, but it also caused immaterial damage, as it meant that customers were unsatisfied with their delivery. „It’s a shame when a premium quality product gets judged by one contaminated pallet,“ explains Jörder.

Together with his colleague, the operations manager eventually turned to Greif-Velox Maschinenfabrik in Lübeck (Germany) to seek help for their problem. Not only does Greif-Velox develop and realise bagging machines, but the company also implements full-line systems involving conveying, palletisation and load-securing systems, tailor-made to meet individual customer requirements.

One example is the BVP 4.40 air packer, for which the Valvomat empty bag applicator and the Valvoseal ultrasonic sealing unit are available as extensions. The Valvomat empty bag applicator can automatically place up to 800 bags onto the filling machine every hour. After being filled by the air packer, the Valvoseal ultrasonic sealing unit welds the bag valves securely and dust-free – generally speaking. As the example of the ICL Group shows, there is still a step between automated placement and ultrasonic welding, which has to be improved.

Optical measuring system developed

When the responsible employees heard about the problem with faulty bag seals at ICL, they worked together with the customer to map out some ideas. The objective: to join forces in order to develop a solution which would be capable of resolving the problem of faulty seals in this specific instance. As the experts observed, there are always bags which are processed incorrectly when it comes to the valve. These deviations from the norm mean that it isn’t possible to automatically place every bag in the exact correct position on the pneumatic packing system. „For instance, if valve openings stick together, the bag will be wonky when put on the spout,“ explains operations manager Jörder. „Immediately after filling, the valve will then be welded shut at an angle.“ Depending on the angle, it can happen that one side isn’t completely sealed. The consequence: a small opening through which the product can escape, ultimately contaminating the entire pallet during palletisation.

As a solution, Greif-Velox developed Valvo Detect, a system which comes into play even before the palletisation stage. Valvo Detect is an optical measuring system which detects whether the bag has been placed at the correct angle. Should the angle be incorrect, the system ensures that this bag can be separated out before palletisation. In this way, contamination of the entire pallet can be prevented.

Sensors detect errors

Valvo Detect is essentially made up of two optical sensors which detect the position of the bag’s valve in relation to the position of the Valvoseal sonotrodes. A light sensor will identify, if the valve is incorrectly placed at an angle to the sonotrode, which would make 100 %-seal not possible. As shown in testing, the optical detection works with different coloured valves, as well as with bent valves. If the Valvo Detect system identifies any irregularities, the filled bag will be digitally marked and can be separated out. This system also provides the opportunity for any rejected bags to be analysed: why were these bags removed? Are there any universal deficiencies in bag quality? If possible, how can the number of rejected bags be reduced?

„Greif-Velox has now found a solution to the problem, which is saving us recall costs in the five-figure mark per year, as well as lots of man-hours in complaint management,“ says operations manager Jörder. „An absolute plus for us: at the end of the day, we also have more customer satisfaction and a better brand reputation.“

Greif-Velox Maschinenfabrik GmbH, Lübeck

Author: Dr. Alexander Mildner

Head of research and


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