Precision Leveling Machine + Horizontal Decoiler The Perfect Combination for Stress-Free Process Optimization

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By smartly integrating a Precision Leveling Machine with a Horizontal Decoiler, DREEFS GmbH revolutionizes its production processes, achieving an impressive 90% reduction in material costs. This technical synergy ensures precise leveling and stress-free handling, boosting efficiency. Learn how DREEFS secures its leading position as a manufacturer of electromechanical switches while maintaining top quality standards.

Founded in 1903 and rooted in Marktrodach, Germany, DREEFS GmbH Schaltgeräte und Systeme is a company steeped in tradition and has firmly established itself as a leading manufacturer of electromechanical switches. The company has been part of the Everel Group since 1996 and has specialized in the production of contacts for all types of electromechanical switches since around 2008.

With an annual turnover of 9 million euros and 23 employees, DREEFS produces around 500 million contacts annually at maximum capacity utilization, mainly with welded silver contacts for electromechanical switches used in various sectors such as household appliances, automotive, garden, outdoor, and healthcare. The modern machinery employed by DREEFS includes nine stamping presses from well-known brands such as BRUDERER, HAULICK ROOS and Mabu, which are exclusively equipped with Bihler welding systems, as well as peripheral equipment from KOHLER and Leicht.The stamping presses have a pressing force of up to 64 metric tons and run for around 5000 hours a year at speeds of up to 1500 strokes per minute in three-shift operation.

Each operator looks after two to three machines per shift. The machines are equipped with state-of-the-art control technology and are monitored by up to four computers withSPC (statistical process control) systems. DREEFS produces stamped and welded parts with an output of 150 to 6400 parts per minute with these machines. This high speed is crucial in order to be able to offer customers prices that are not only competitive but also extremely attractive.

DREEFS mainly produces parts for internal production sites in Italy and Romania, whose customers include renowned companies such as Volkswagen, BSH, Miele, Elektrolux, Gorenje, WOLF, Franke, Hisense, and Amica, and supplies markets in Europe, Turkey, the USA, and Mexico, as well as elsewhere.

DREEFS mainly processes copper alloy strips for the manufacture of switch contacts. Every year, some 800 metric tons plus around 2700 kg of silver are used to weld the contacts. The material thickness varies between 0.12 and 0.8 mm and the width between 5 and 65 mm. The company predominantly uses horizontal decoilers from Leicht Stanzautomation GmbH to unwind the strips and feed them into the stamping presses. The progressive tools used mainly comprise two to eight stations. This delivers a production output of up to 1100 welded parts and 6400 stamped parts per minute. Some of the finished products are wound onto spools as endless strips using Leicht vertical rewinders, but the majority of products are stamped as individual parts in boxes. For machines that produce class A parts, Leicht box changers are used in a paternoster system or in a rotary table format.

Welding is carried out almost exclusively using BIHLER welding technology. The biggest challenge in this area is ensuring that the silver contacts are properly welded onto the substrate material. To fully guarantee that the contacts are successfully welded, the raw material must be leveled.

Cutting Costs with Level, Low-Tension Strips

In order to achieve perfect welding results and further optimize its production processes, DREEFS decided to use a horizontal decoiler from Leicht's PWL-150 series in conjunction with a CPL 120 precision leveling machine from KOHLER Maschinenbau GmbH. There were a number of factors behind this decision, not least the fact that the substrate material for a large number of contact parts has been changed from half-hard brass to unalloyed DC01 steel for cost reasons, meaning that leveling and smoothing the material is essential.

“Integrating the compact precision leveling machine into the control system of the horizontal decoiler has considerably reduced the complexity of the material handling process and saves both time and space when placing and threading new coils. What’s more, it has reduced waste and improved the welding results. The compact design of the decoiler and integrated leveler with its extremely small footprint appealed to us immediately. The switch from brass to steel strips, which generated material cost savings of around 90%, would not have been possible without the CPL 120 from KOHLER. This has made the production process more efficient overall. With many years of excellent experience with a KOHLER leveling machine that has been in use since 1979, we are repeat offenders in the truest sense of the word and have once again opted for the market leader in precision leveling machines for this purchase. We have similarly good experiences with Leicht products in materials management. The horizontal decoiler with integrated precision leveling machine is the optimal solution for us,” says Harald Müller, Managing Director of DREEFS GmbH Schaltgeräte und Systeme.

Precise Leveling Results Thanks to Optimum Roller Diameter

In addition to its compact design, particular attention has been devoted to the number and design of the leveling rollers in the KOHLER CPL 120 precision leveling machine. The 19 leveling rollers are supported by a large number of supporting rollers, which ensures a high level of rigidity. The small roller diameter ensures that even the thin strips normally used in the industry can be leveled with precision. Easy accessibility allows for quick and straightforward cleaning of supporting rollers and leveling rollers. This protects the strip material from dust, dirt particles, and damage. The machine also exhibits high rigidity in order to compensate for leveling pressure.

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Leveling with a High Degree of Plastification even for Thin Strips

 The CPL 120 enables degrees of plastification of more than 70 percent to be achieved, reliably eliminating tension and unevenness in the strip material. The result is a much more stable production process for components that meet even the most stringent precision requirements. Operating costs can also be reduced, as there are fewer rejects and the stamping tools can be designed with a reduced degree of complexity, ultimately resulting in longer service lives.The machine is ideal for leveling strips up to 0.8 millimeters thick and more. The settings can be configured with sensitivity and precision. The leveling process is always stable and delivers optimum, reproducible results. “The leveler combined with the horizontal decoiler is simply brilliant,” says Thomas Weber, Shift Manager at DREEFS.  

Optimum Quality Assurance Thanks to Industry 4.0

Thanks to the almost seamless integration of all processes in accordance with the Industry 4.0 standard and the networking of all machines via an MES system from MARPOSS, DREEFS can seamlessly track the entire production process right down to the individual contact parts and their boxes or coils at any time. This means that all stamping and welding parameters can be continuously monitored and recorded. It is also possible to assess the quality of the raw material and any quality fluctuations, and ultimately the leveling results achieved. High-speed production with800 welded parts per minute requires a gentle material feed and optimally leveled strips before reaching the welding process.

The slightest distortion of 0.05 mm would lead to a poor welding result, and this in turn could pose a considerable risk in the final application, e.g. in an oven. If there is no silver contact, the oven switch would melt and continue to heat the oven in the on position with no possibility of switching it off, which could ultimately lead to a room fire.As part of quality assurance measures in accordance with Industry 4.0, defective parts are sorted out at DREEFS or the machine is stopped if there are minimal deviations from the standard process parameters. All parameters are stored and can be used to perform a comprehensive analysis if required.

Stress-Free from Start to Finish

The collaboration between DREEFS and cooperation partners Leicht and KOHLER has been smooth and stress-free throughout. The perfectly coordinated machines from KOHLER and Leicht play a key role in optimizing production processes and enable DREEFS to maintain its high quality standards while increasing efficiency. The switch from copper alloys to cold-rolled strip is currently being considered for other products. This has the potential to generate enormous savings thanks to the lower material costs. DREEFS will continue to rely on the products and support of Leicht and KOHLER in the conversion of its processes.