Programming in 5 minutes instead of a whole day
In 1981, the Louis Sauter company purchased a metal press. It ran without a hitch for years, creating lids and shapes from both preprinted and unprinted sheet metal – before breaking down completely. However, rather than replacing it, Eric Cossy, process engineering manager at Louis Sauter, chose to go with a retrofit instead. To this day, he has not regretted the decision.
Louis Sauter has been manufacturing tin cans for the food industry, the cosmetics sector as well as technical industrial branches since 1875: everything from tin cans to aerosol cans and special metal prints. The company greatly depends on the availability of a well-functioning metal press every day. A breakdown could result in horrendous costs. When that breakdown finally became a reality, the associated costs and the downtime also offered the most important arguments against replacing the press – and for retrofitting it instead: “With a delivery time of over half a year, a new metal press would have cost us over a half a million francs,” Cossy explains. “We calculated the estimated downtime of approximately four months for the upgrade to roughly cost us 100,000 francs.“ As a result, the decision in favor of an upgrade looked appealing right from the start. However, practically nobody could have imagined that the retrofit would not only save costs, but also create new opportunities.
Finding the best solution together
Louis Sauter commissioned Elwetec from Wetzikon, Switzerland for the electromechanical upgrade, which in turn commissioned the Siemens Solution Partner WITO Automation for the control technology implementation. WITO specializes in industrial automation technology services, including consulting, concepts, specifications documentation, electrical planning, engineering as well as plant and machine simulation. It has relied on Siemens products for a long time already – also in handling this project. Together, all of the involved parties collaborated in finding the best solution for Louis Sauter, starting with the equipment.
«The flywheel motion of the metal press posed the greatest challenge. It regulates the amount of time needed to automatically position the metal sheet. During the full 360° rotation, a sensor continuously signals the exact position of the flywheel to the PLC. At just the right moment, it directs the sheet positioning with the help of the rotation axes,” as project manager Martin Glarner reports. It thereby uses interrupts, which all CPUs are capable of accepting. «We went with a sampling rate of five milliseconds in this case.» In selecting the CPU, Glarner calculated which controller would be best suited for fulfilling the demands. The result? SIMATIC S7-300 with a CPU 315-2 DP and PROFIBUS interface. It greatly reduces costly wiring while also offering tremendous reliability.
Time savings of 50%
A SIMATIC Touch Panel TP 177B was chosen to serve as a data entry and visualization workstation, with which Eric Cossy and his staff are very pleased: “The job program for a new punch workpiece can be entered completely over this panel. Thanks to the sophisticated WITO program, only a few input data are thereby needed. The controller calculates the rest. What’s more, data entry only takes a few minutes.“ According to Cossy, the metal press can now be converted with time savings of up to 50%! The reason? An archived program can be called up for repeatable parts series requiring but a few finger taps – and just like that the controller is ready for a new application. “Previously, we needed a whole day. Now we can do it in one to two minutes! The touch panel control makes controlling the machine very easy.”
An enthusiastic operating staff
Not only for repeatable parts series, also program adjustments can now be performed twice as fast as before. “With the touch panel, it’s done in no time while the metal press is running.” It provides significantly increased convenience and operational safety. But those are not the only advantages offered by the retrofit. Because the Siemens Partner wanted to be sure, Glarner set up the entire controller in his office prior to handover, and connected it to the SIMIT Simulation Framework from Siemens. It allowed him to run the controller as in the simulated plant environment. Every module of the software was tested and the entire solution was run in the simulation mode. The result? The time needed for the software commissioning was cut in half! What’s more, if the customer should choose to make further adjustments at a later time, they can first be simulated to ensure trouble-free solution functioning. “We simulated various process flows and familiarized ourselves with the control system ahead of time. It was a completely successful retrofit,” Cossy is pleased to report.
... and also client
For Eric Cossy, a lot more was accomplished with the retrofit than simply repairing the metal press: “The automation provided by the SIMATIC S7 has not only helped to greatly speed up the entire programming run, it has also become much safer. What’s more, we were able to increase the positioning precision from 0.1 millimeter to 0.05 millimeter!“