Greif-Velox ValvoDetect: No product loss and no contamination during filling

Leaking packaging is a very critical factor, especially for foodstuffs. For this reason, special care must be taken when filling food powders to ensure that no product is contaminated or pallets are rendered unusable. For this reason, Maschinenfabrik Greif-Velox has developed the ValvoDetect optical measuring system: It ensures that faulty bags can be detected and ejected at two points in the bagging process. This avoids contamination and thus complaint costs.

Product protection is essential in the food sector. However, as Greif-Velox has learned in discussions with its customers, the same problem occurs time and again with powder producers: After the bagging process, individual bags are not sealed correctly. The result: the product escapes in an uncontrolled manner and contaminates entire pallets. To prevent an otherwise flawless product from being returned due to individual defective bags, leaving the end customer dissatisfied and damaging the brand reputation, the Greif-Velox development team went into analysis: What causes bags not to be sealed properly after the filling process?

Development team solves long-standing problem in the bagging of powders

In addition to bagging machines, Greif-Velox Maschinenfabrik also implements full-line systems including conveyor technology, palletizing and load securing to meet customer requirements. Time and again, the development team solves problems that have existed in the industry for a long time. In the case of incorrectly sealed bags, the development team led by Dr. Alexander Mildner discovered that the problem did not lie in the sealing. According to a study by the TH Lübeck, the ultrasonic process used by Greif-Velox provides a 60 percent higher tear resistance of the bag valves compared to conventional processes. The source of the error lies much more in the placement: in some cases, bags are placed at an angle on the valve spigots immediately before the sealing process due to deviations from the standard or incorrect settings of the bag chair. Depending on the angle, it can happen that one side is not completely sealed and the product escapes at this point, which then leads to contamination of the entire pallet.

ValvoDetect detects incorrectly fitted bags before sealing

To prevent this from happening, Greif-Velox developed the ValvoDetect feature, a system for the BVP gross pneumatic packer that starts before the palletizing or welding process: Two optical sensors check whether the bag valve is attached in the correct position in relation to the welding sonotrodes. If the light scanners detect that this is not the case, meaning that the sealing may not be 100% successful, three previously defined actions can be carried out.

On the one hand, the machine can be stopped so that the operator can readjust the bag support setting so that the subsequent bags are in the correct position and are sealed correctly. On the other hand, it is possible to stop the machine only when there is a predetermined percentage deviation or to automatically eject the affected bag from the system without interrupting the process so that it does not end up on the pallet. This is particularly advantageous if machine downtimes are to be kept to a minimum. In addition, sacks in which the sensors detect an irregularity can simply be recorded statistically without any further action. The appropriate parameters can be defined and preset for each product or bag size depending on the type. Customers report that the use of the optical measuring system has enabled them to save EUR 20,000 in complaint costs and EUR 8,000 in cleaning costs within a year.

High savings in cleaning and complaint costs

After ValvoDetect had been sufficiently tested in this development stage and used by the customer, the development team was able to take a closer look at the bags that did not sit correctly in the seal and were marked or rejected accordingly during the process. The result: a significant proportion were not sitting incorrectly in the seal due to certain settings, for example on the bag support, but because they had not been picked up correctly at the start of the process. This means that the bagging process can be made even more efficient if incorrectly processed bags can be sorted out before filling and not just before the sealing process.
Based on this observation, the Greif-Velox team further developed the ValvoDetect feature and equipped it with additional sensors in the front part of the system: After the bag has been automatically gripped from the empty bag magazine at the start of the filling process and the valve has been opened using the spreading fingers, the correct opening of the valve is scanned in this position. The light points of the sensors check whether the sides of the bag are present. If they are dented or torn or the bag has not been opened correctly, this is detected. In this case, the damaged bag is discarded and does not continue to the filling process. Users report that, with a bag error rate of 0.5 percent, they were able to recover 9,000 euros from complaints to the bag manufacturer alone and save a further 8,000 euros in cleaning costs.

Greater process efficiency and higher end customer satisfaction

"This system is particularly useful in combination with the inspection processes at two points," says Dr. Alexander Mildner about ValvoDetect, which is now protected by a utility model in Germany. "At the start of the bagging process, the system checks whether the bags are correctly inserted into the system, and once this has happened, it checks whether the valve is correctly seated in the seal after filling. This ensures maximum process efficiency and ultimately greater customer satisfaction."