Sheet metal blanks and welded assemblies made of various steel materials are a speciality of Deutsche Erz- und Metall-Union GmbH (Deumu) in Salzgitter. The finished parts must be as flat and stress-free as possible for further processing. For this purpose, the company relies on a Peak Performer parts leveler from Kohler Maschinenbau GmbH. This convinces with numerous trend-setting technical features – and last but not least with optimal judging results and high flexibility.
Steel and metal processing companies across all industries have been confronted with the same challenges for years: Customers are placing ever higher demands on quality, speed and flexibility, while at the same time international competition is becoming tougher and more intense as a result of ongoing globalization. This also affects the procurement of the required materials: Since many companies simply do not have the capacity to carry out all processing steps economically in-house, these are increasingly being outsourced to suppliers. As a result, numerous steel traders are increasingly developing from pure suppliers into flexible service providers and manufacturing partners.
A long-standing expert in this field is Deutsche Erz- und Metall-Union GmbH, or Deumu for short. The company specializes, among other things, in the processing of steel scrap, in logistics and purchasing services and in steel processing. As a wholly-owned subsidiary of Salzgitter AG, Deumu Stahlbearbeitung now employs around 70 people and generates sales of around 18 million euros a year.
Extensive machinery for sheet metal processing
At the beginning of the 1980s, Deumu began producing flame-cut blanks for the steel group and its customers on the site of the steelworks in Salzgitter. Suppliers include manufacturers of construction machinery, the railway industry, the wind energy sector and general mechanical engineering. In order to be able to manufacture the desired products in the required quality, Deumu relies on an extensive machine park:
Two plasma and two oxyfuel flame cutting systems, a five-axis chamfering robot for weld seam preparation, a continuous blasting system and various press brakes are used at the site. With the Peak Performer 130P.2000 from Kohler Maschinenbau, the company also has a state-of-the-art, high-performance parts leveler.
Deumu mainly processes plates made of structural steels such as S355, high-strength fine-grained structural steels such as S700 and S960, and wear-resistant special structural steels. Depending on the customer’s requirements, this is used to produce cut-to-size parts or complete welded assemblies, which the company can also machine and paint.
“The parts are cut from sheet metal panels on the plasma or oxyfuel torches and then cleaned and blasted,” says production manager Thomas Kleinwechter, describing the manufacturing process. “If required, weld preparation is carried out before all blanks are straightened and further processed into assemblies, depending on the order.” Deumu also straightens entire sheet metal panels, which are first cut to size at the customer’s premises, on its own machine before delivery.
Consistently high product quality due to partial straightening
“Consistently high quality is essential for our customers,” Kleinwechter emphasizes. “We therefore work to the regulations of numerous certifications and approvals such as ISO 9001, ISO 14001, ISO 18800 and railway approval.” High demands are therefore also placed on the flatness of the manufactured parts: The usual tolerance is one mm per meter or better. Therefore, straightening is a central step in the process chain.
“The parts are not only flat afterwards, but also less stressed,” Kleinwechter reports. “This gives us decisive advantages for further processing, for example higher fitting and repeat accuracy during edging as well as significantly reduced distortion during welding.” About 400 tons of material are straightened at Deumu on average every month.
For decades, the company has used a mechanical dividing leveler for this purpose. However, this was getting on in years and was no longer up to today’s requirements: the high maintenance effort was increasingly becoming a time and cost factor, the necessary flexibility was not given, and the judging result could no longer meet the high demands of the customers.
“It was clear from a long time ago that we had to make a change here,” Kleinwechter recalls. “At the Euroblech 2016 trade fair in Hanover, we had already set our sights on Kohler as a supplier. We then came into personal contact two years later at Cutting World in Essen.”
Partial leveler with numerous advantages
With approximately 60 years of experience, Kohler is the technology leader for innovative straightening technology. With the Peak Performer series, which has been successful for years, Kohler offers high-performance and energy-efficient dividing levelers for numerous applications. These are used in particular for the straightening of parts, blanks and also whole metal sheets.
The machine comes up with a number of trend-setting technical features:
– servo-electronic machine concept without any hydraulics
– electromechanical gap control
– intelligent overload protection
– extended cleaning system and
– powerful and energy-efficient direct drives
The straightening rolls, for example, are driven by a direct drive. This increases energy efficiency, reduces wear and makes it possible to straighten larger cross-sections. “Hydraulics are not needed in this system,” Kleinwechter explains. “That’s why it was clear to us from the outset that the maintenance effort in operation would also be significantly lower.” Leakages are thus excluded, the drive is insensitive to temperature fluctuations and is also extremely environmentally friendly due to the lower power consumption.
Another advantage of the Peak Performer is its extended cleaning system for easy cleaning of the straightening rolls and back-up rolls. This allows both the upper and the lower straightening unit to be extended by electric motor. When extended, all components can be cleaned very easily. The reversible straightening rolls also ensure a longer service life, especially when straightening narrow parts on machines with a large throughput width.
Kohler’s patented electromechanical straightening gap control ensures consistently good straightening results and thus compliance with Deumu’s quality requirements. The Gap Control, which is based on a wedge system, reliably keeps the straightening gap constant. In this way, even complex parts with changing geometries and made of high-strength materials can be aligned excellently.
Extra-wide back-up rollers have also been installed to provide particularly rigid support for the straightening rolls. “The Peak Performer’s arguments convinced us all round,” says Kleinwechter. “In addition, there was a lively exchange of information between us and Kohler from the very beginning. We got answers to all our questions, and Kohler was able to prove the required straightening quality beyond doubt through various tests in their own straightening center. So we knew exactly what to expect from the machine.”
Individually fitted into the existing production
Deumu managers therefore decided to replace their existing parts leveler with a Kohler Peak Performer 130P.2000. This model is designed for a maximum throughput width of 2000 mm and material thicknesses up to 40 mm.
The replacement with the existing machine took place in 2019 – whereby Kohler also had to make adjustments to the specific conditions, as Kleinwechter recalls: “The access to the control cabinet had to be changed due to a column in the hall. We also designed the roller conveyor in such a way that the operator can optionally also place a pallet between the transport rollers.” The result is a system that fits perfectly into Deumu’s existing manufacturing process.
Production manager Thomas Kleinwechter is more than satisfied with the outcome of the project: “The Peak Performer has given us even more of an increase in quality than we would have expected,” he sums up. “After about two years in multi-shift operation, we are completely convinced we made the right decision.” Kohler’s parts leveler provides Deumu with the precision, flexibility and performance needed to meet all of its customers’ future needs.
In a next step, Deumu and Kohler will jointly introduce a solution for visualizing the processes. Further projects in the environment of Industry 4.0 are already being considered.