Checkweighing for paint and plaster manufacturers

Due to new regulations, a paint and plaster manufacturer had to switch to automatic checkweighing. For this purpose, a highly flexible weighing solution was installed that can handle a wide range of product sizes.

The main challenge for manufacturers when filling paints and liquid plasters is the large weighing range of the containers to be weighed. The customer's variations of this best practice range from 1 kg to 50 kg net per container. The manufacturer Minebea Intec supplied a highly flexible weighing solution for the legally required checkweighing.

The German company, which specializes in plasters and paints, was already successfully using a Minebea Intec weighing solution for product filling. New regulations required a changeover from automatic filling to automatic checkweighing. Four belts were required to handle a variety of product sizes, from small to large. The planned system had to offer a large weighing range with high resolution in the small range and high preload by the conveyors.

The project objective was clear: a highly efficient weighing solution was required that also covered an exceptionally large weighing range. The weighing process at the manufacturer was further complicated by the different properties of the plaster and paint products - such as the flow speed. As a result, the individual products had to be assigned to specific filling systems; it was not possible to divide the production lines purely according to filling quantity. A flexible weighing solution was needed that would cover the range from 1 kg to 50 kg for the prescribed downstream checkweighing.

The special solution created by Minebea Intec consists of an IS weighing platform (ISEDE-50-OAW), which is defined as a multi-interval scale with 20kg/2g and 50kg/5g and a preload of 25 kg due to the conveyor belts. This resolution fulfills the requirements of the German Packaging Ordinance and is the only solution on the market with this special weighing range. The connected Maxxis 5 weighing controller as a freely programmable terminal and an "Automatic Checkweigher" project application takes over the control tasks and communicates with the higher-level controller either directly via digital signals or via the fieldbus - in this case Profinet. The control data is transferred to the Maxxis weighing controller via OPC and forwarded to the SPC Enterprise for logging.

This combination of Maxxis 5 weighing controller and IS weighing platform has been approved by the PTB as an SKW scale. The system runs in start-stop mode, i.e. the Minebea Intec systems stop the belt and weigh at standstill. The producer completed the first installation in 2022 and has since equipped two more plants with the system. The verification officer who had to confirm conformity carried out the required measurements, all of which were well below tolerance.

The manufacturer is very satisfied with the results from the first year. The previous concerns that this high-resolution IS weighing platform would not withstand the mechanical load or that the start-stop operation would slow down the system have been allayed. The performance is still very precise and stopping in these applications took less time than the filling itself: one to five seconds, depending on the container. Once again, Minebea Intec has proven that no individual challenge is too great for the company's weighing and inspection technologies. (OM-6/24)