In recent years the terms “digitization” or “digital transformation” have become favorite industrial catchphrases. Digitization is supposed to help companies streamline their operations and make their manufacturing processes more stable. A lot has been written about digitization, although reports about how it has actually improved actual industrial operations are still relatively rare. In this article, we are highlighting some digitization success stories from the field of mass finishing, specifically the management of process water cleaning and recycling systems with centrifuges. Under its “Smart Solutions” brand, a global leader in the field of mass finishing developed a digital process water management system. The primary goal was to shift the process knowledge from people to digital tools, thereby minimizing the need for human experience. The system produces not just a more stable production environment but results in higher product qualities and lower operational costs as well. Above all, it more or less completely eliminates the risk of human error.
Process water recycling with
With very few exceptions, practically all mass finishing processes require finishing compounds and water. In a 24/7 production environment, certain mass finishing operations are gobbling up several million liters of water and more than 40 tons of compound per year. This is not only bad for the environment but also quite costly, so it is not surprising that in most mass finishing operations, centrifuges are used for cleaning and recycling the process water. This helps reduce the water and compound consumption by 90 to 95%, and therefore represents a significant contribution towards saving precious resources, a cleaner environment and of course, saving costs.
Managing a centrifugal water cleaning and recycling system is complicated
But process water recycling operations can be quite complex. Numerous operating parameters such as the pH-value of the process water, the compound concentration, the water hardness, the chemical oxygen demand, the potential for bacterial infection or the water conductivity must be regularly monitored. And, of course, mass finishing processes are constantly changing. For example, in a stamping operation the amount of oil carried into the finishing machine(s) may suddenly increase. Or the mains water is becoming harder or softer. Or a changing workpiece mix demands the use of a different grinding media and/or compound.
If no adjustments are made, such process mutations can completely throw a process water recycling system out of balance resulting in excessive foaming, longer cycle times, bacterial infestation of the process water creating an extremely unpleasant smell, etc. Above all, the desired finishing results are no longer achieved, and the entire process can completely collapse.
To date, the management of centrifugal process water cleaning and recycling systems has to be done manually by experienced personnel. The operators must decide whether the compound dosing rate must be increased or decreased, a water hardener must be used, the water flow rate must be changed, the entire process water batch must be replaced, or an anti-bacterial agent is required. However, considering that humans are generally flawed, even with much knowledge and experience, this approach carries the risk of human error! And it can have adverse consequences in the form of poor finishing results and higher costs.
A way out of the dilemma – the digital process water management system
With the digital process water management system, the process knowledge has shifted from humans to digital tools that continuously monitor all critical process water parameters without requiring any human interaction. As such, the system acts as an early warning system that registers any deviations from the established values, be it the compound concentration, the pH value, the water hardness or the water flow rate, etc. But it actually does a lot more! Whenever it finds a parameter to be out of range, it automatically takes steps to bring the parameters back in line.
The need for human intervention in the form of manual measurements and corrective actions has practically become superfluous.
How does the system work?
Special sensors are automatically measuring all critical process water parameters. Manual measurement is no longer needed. Operator error is, therefore, completely eliminated.
The system automatically analyzes the measured parameters and develops appropriate corrective actions. Human experience and knowledge are to a large extent replaced by the “artificial intelligence” of the digital system.
With suitable digitally controlled devices, such as dosing systems, flow regulators, etc., the respective parameters are then automatically adjusted. This keeps the entire process water cleaning and recycling operation in perfect balance
All relevant parameters are electronically recorded, thus allowing complete traceability of the process water parameters at any time. Such traceability is increasingly demanded in many industries like automotive, aerospace, medical engineering, to name just a few.
Since the system is cloud based, it allows the supplier’s service engineers to access and trouble shoot a particular process water installation from practically anywhere in the world. This is especially beneficial, when new work pieces and different finishing requirements force a customer to change a mass finishing process and adapt the process water system accordingly.
Some success stories
A leading supplier of gasoline and electrical chainsaws is operating several centrifugal disk machines for finishing the cutters and links for the saw chains. The automatic centrifuges utilized for cleaning and recycling the process water from the finishing machines are handling several million liters of water per year. When the company modernized its mass-finishing operation, it also installed the digital process water management system. With resounding success:
The system completely eliminated the need for manual monitoring, evaluation and adjustment of the process water parameters. This left the operator with only a supervisory function, freeing him up for other work in the finishing department. In addition, by increasing the consistency of the cleaning and recycling operation, the digital management system significantly extended the time span between process water changes by over 50%. The resulting compound and water savings, along with the drastically reduced personnel requirements, produced annual cost savings of thousands of dollars.
An automotive supplier makes stamped and bent components from various steel alloys, stainless steel and non-ferrous metals. The mass finishing operation demands not only excellent deburring and edge radiusing results, but the workpieces must also be perfectly clean for the subsequent optical quality control. Because of inconsistencies in the centrifugal process water cleaning and recycling system, the finished workpieces were frequently covered with media and metal residues. Since this prevented an effective quality control, costly reworking in the form of extra cleaning operations was required.
With the digital process water management system, this dilemma could be completely resolved. The real-time monitoring and automatic adjustment of the process water parameters ensures that the liquid remains consistently stable at the required high quality.
After installation of the digital management system, the finished workpieces became perfectly cleaned so that additional cleaning operations were no longer necessary. This saved a substantial amount of money in extra rework.
A company, specialized in manufacturing balancing weights for automotive wheels, is utilizing an automatic centrifuge for cleaning and recycling the process water in its mass finishing operation. The balancing weights are made from steel and zinc. While the steel weights require a good corrosion protection, the zinc components must have a surface tension of 33 mN/m for the subsequent coating operation. The different requirements constantly cause a too-high or too-low compound concentration in the process water. This resulted in considerable rework and relatively large quantities of scrap parts. In addition, the process water was frequently contaminated by bacteria requiring costly process water changes.
The digital process water management system produced a much more stable process and drastically reduced the rework and scrap rate. Moreover, it significantly increased the uptime of the process water with the result that considerably fewer water changes are necessary.
Conclusion and outlook
The above examples show that digitization does not have to be just an empty slogan but that it actually helps improve the quality of products and, at the same time, saves costs. In the described success stories the payback period for the digital process water management system did not have to be calculated in years, but the return-on-investment was already achieved in a few weeks.
Considering the quality improvements and financial benefits it produces, digitization no doubt will rapidly gain importance for all kinds of mass finishing processes.
Contributing Editor MFN and
Rösler Oberflächentechnik GmbH