Digital process water management for optimized vibratory finishing results

For quality monitoring of process water from vibratory finishing, a manufacturer of stamped and bent parts has upgraded. The new digital process water management system enables interactive monitoring of up to 13 parameters.

The recirculation of process water from vibratory finishing operations is a necessity today for economic and ecological reasons. The quality of the treatment has a decisive influence on the vibratory finishing process. In order to keep an eye on the many influencing factors that have to be taken into account, Scherdel, a globally active manufacturer of stamped and bent parts, has retrofitted its semi-automatic Rösler Z 800 centrifuge with digital process water management from Rösler Smart Solutions. The solution enables interactive monitoring of up to 13 parameters - for example compound concentration, pH value and microbiological load. In the event of deviations of individual parameters from the individual setpoint, the intelligent software provides directly implementable recommendations for action to the operating personnel.

Rudolf Diesel experimented on the world's first diesel engine with springs from the wire drawing plant founded by Siegmund Scherdel in 1889. In the meantime, the Scherdel Group covers a broad spectrum from forming technology to assembly and joining technology to surface technology as well as machine, tool and plant engineering. The company, which today has 32 locations worldwide, is at its customers' side as a partner from briefing to series production. The result is premium products that are used not only in the automotive industry but also, for example, in medical technology, electrical engineering and power engineering. This also includes the stamped and bent parts, spring rings and components for electromobility that are manufactured at Scherdel Waldershof GmbH & Co. KG in Waldershof, Bavaria.

The components made of various steel alloys, stainless steels and non-ferrous metals are partly given the perfect finish in vibratory finishing processes. In addition to the actual machining task, such as deburring and edge rounding, technical cleanliness in line with requirements and clean surfaces are important quality features, so that visual quality control can be carried out perfectly. The quality of the process water plays a decisive role in this.

The process water from the vibratory finishing process is recirculated at Scherdel Waldershof and treated by a semi-automatic centrifuge. However, monitoring of the process water quality was only carried out to a very limited extent in the form of a daily check of the compound concentration and with changing personnel who did not have in-depth know-how on the treatment and monitoring of the process water. "The process water quality changes due to the input of oils from the stamping-bending processes and strip lubricants, as well as material and abrasive wear. On the one hand, conductivity increases, which led to erroneous results in the optical tests. On the other hand, the specifications regarding particle sizes and quantities were not always adhered to, resulting in costly reworking or even rejects," reports Tobias König, Surface Vibratory Finishing / Cleaning Department Manager at Scherdel Waldershof.

Accordingly, the department manager was very interested when the use of the digital process water management solution "Advanced" from Rösler Smart Solutions was proposed to him as a pilot user. This new product for process water treatment for semi- and fully-automatic centrifuges enables user-oriented monitoring, recording and evaluation of essential process parameters. These are: Compound concentration (titration or refractive index - BRIX), pH, conductivity, water hardness, microbiological load by bacteria, yeasts and fungi, chloride content, COD value (chemical oxygen demand), BIT content (biocides in process water), appearance and odor. Adapted to the respective requirements of the vibratory finishing process, the parameters to be monitored can be selected individually.

In the first stage of the "Advanced" package, sampling and analysis are carried out manually using appropriate measuring equipment, which can be supplied on request. The values determined are also entered manually. On the basis of the data entered, the algorithm stored in the software calculates directly implementable recommendations for action in order to bring any deviations from the previously defined target or tolerance value of one or more parameters back into the specified range and thus ensure process stability. The recommended actions also contain explanations of the consequences of deviations of the respective parameter on the processing quality. Since all parameters are stored, the data can be accessed in the form of tables and history diagrams. The latter makes it possible to avoid unplanned interruptions to operation due to a necessary change of process water and to schedule a new start at a time that can be optimally integrated into the operating sequence.

"Rösler introduced us to digital process water management and we immediately recognized the potential to achieve greater transparency and process reliability through this solution. In addition, we saw the opportunity to significantly improve the process understanding of our employees through the recommended actions with corresponding explanations," explains Tobias König.

Scherdel Waldershof uses digital process water management for a semi-automatic Z 800 centrifuge from Rösler, which supplies process water to a vibratory finishing system (Rösler R 620) running in three-shift operation. The compound concentration and the pH value are monitored once per shift. Conductivity is measured once a week. The microbiological load of the process water is checked as required. This is the case, for example, when appearance and odor, which are also recorded regularly, provide indications of a change. "The measurements and the recording of the values determined are simple and quick to perform. The time required to measure and record the compound concentration and pH value is almost identical to that of the controls before," describes the department manager. "However, today we receive a clear evaluation and, in the event of deviations, easily understandable and directly implementable recommendations for action that are issued automatically. This definitely helps to keep both process water and part quality stable, thereby reducing rework and scrap by up to 50%."

However, recommendations for action are not only available for setpoint deviations, but also for certain quality-reducing occurrences such as corrosion on the parts, a buildup of foam in the vibratory finishing process, and insufficient part cleanliness that affects downstream processes, for example. To eliminate these problems, the recommendations for action contain various measures as well as explanations of the interrelationships in the process. "The colleagues in the department usually have no special training on the subject of vibratory finishing and process water. The recommendations for action mean that they not only know what to do if the worst comes to the worst. They also receive appropriate background knowledge, so that awareness of the connections between process water quality and part quality is strengthened," Tobias König notes in conclusion. (OM-3/23)