Burghardt + Schmidt GmbH
The unwinding unit accepts coils up to 750 mm in diameter and 730 mm wide.
The unwinding unit accepts coils up to 750 mm in diameter and 730 mm wide.
The unwinding unit accepts coils up to 750 mm in diameter and 730 mm wide.
The unwinding unit accepts coils up to 750 mm in diameter and 730 mm wide.
The unwinding unit accepts coils up to 750 mm in diameter and 730 mm wide.

Precision Slitting Line for High-Quality Strips

Sept. 26, 2022
A new precision slitting line from Burghardt + Schmidt GmbH plays a central role in the production of high-precision zinc-based strips.

Zinc is a versatile metal from which Grillo-Werke AG manufactures a range of high-quality products—including customized special strips. The strips are used, for example, for organ pipes, fuses for special vehicles, in textiles & fashion, in construction, and in the automotive sector. 

A new precision slitting line from Burghardt + Schmidt GmbH plays a central role in the production of high-precision zinc-based strips.

Grillo-Werke’s Metal Division covers the entire value chain from zinc production to the production of finished and semi-finished products made of zinc and its alloys. The company operates a foundry and a rolling mill to produce customized zinc alloys.

"Generally, the customer does not prescribe the alloy but specifies parameters such as strength, deep-drawing capabilities, and other deformation properties. We then check which zinc alloy best meets the requirements and produce it ourselves in our factory," explains Dr. Peter Staubwasser, Production Manager in the Metal Division of Grillo-Werke AG.

In the metal strip sector, the focus is on order-specific strips, sometimes in small batches. For their production, the company manufactures the coils itself. Bernd Kasprowicz, responsible for the distribution of zinc strips, explains:

"For us, 50kg batches are common, sometimes batch sizes of 500kg or 1000 kg are ordered. We, therefore, need a flexible machine park that covers a large portfolio with many small set-ups."

This also applies to slitting lines that cut raw strip wound on coils into strips with the desired widths. The thickness of the raw strip is already brought to the desired dimension in the rolling mill. In the factory, an older slitting line had to be replaced because it could no longer meet the growing demands for quality, accuracy, and flexibility.

The Focus Is on Special Strips of High-Quality With Exact Dimensional Accuracy

"The highest priority is burr-free cutting and tolerance accuracy", clarifies Dr. Staubwasser. "To ensure the high dimensional accuracy, cutter shafts with the highest concentricity, a high degree of synchronization of the drive, and precise clamping of the individual plant components are required," adds Bernd Kasprowicz.

Under no circumstances should the strip bend.

After an extensive evaluation round, the contract for the construction of the new plant was awarded to Burghardt + Schmidt GmbH. Dr. Staubwasser explains why Grillo chose this provider: "We have been working together for around 20 years and have in the meantime purchased several plants that have proven to be very reliable in many years of production operation. In addition, among all providers, the Burghardt + Schmidt GmbH met our expectations the best."

Bernd Kasprowicz complements this statement: "We see Burghardt + Schmidt as a qualified supplier for slitting lines that meet our high-quality standards for zinc strips."

Only through close cooperation with the customer can a project like this be brought to a successful conclusion, because there is no standard for precision slitting lines. Thomas Baral, Managing Director of Burghardt + Schmidt, makes clear: "We make each plant tailor-made according to the customer’s requirements. We carefully determine what the customer’s requirements are and advise him on what makes technological economic sense. At the end of this process, we can design and build the desired plant. For Grillo-Werke AG, a compact slitting line with maximum precision cutting was the optimal solution."

Fewer Additional Functions Lead to a Smaller System

So what makes the system so compact? On the one hand, there is the lack of extras that Grillo does not need: The slitting line has no automatic coil loading device, no mechanical surface inspection, and no looping pit.

Secondly, the size of the system depends on the maximum coil diameter. The system accepts coils up to 750 millimeters in diameter. The maximum width of the coils of 730 millimeters also limits the size of the system. Two rewinders contribute to the compactness of the lines. In a line with only one take-up reel, without further design measures, the strips would run parallel without spacing after cutting, rubbing against each other, and deforming.

A small distance between the strips is therefore required for process-safe operation. You could fan out the strips a bit, but that would make the installation longer.

Burghardt + Schmidt has therefore implemented a solution with two take-up reels. With adjacent strips, one runs onto the upper rewinder and the other onto the lower rewinder. On cooperation in project planning and commissioning Dr. Staubwasser says, " Burghardt + Schmidt was given the specification that the system, including the safety fence, must be a maximum of 6 x 7 meters in size. It should be flexible for small batch sizes and cut to an accuracy of about one-thousandth of a millimeter." 

Together with other specifications, Burghardt + Schmidt was able to build and commission the desired slitting machine within the agreed time and cost framework.   The line produces a thin strip with a material thickness of 0,1 to 2 millimeters at a speed of up to 50 meters/minute. It can produce up to 10 strips with widths between 20 and 700 millimeters.

Right from the start, the new precision slitting machine proves its first-class cutting quality. Even with a high number of strips, the cut burr is minimal and the winding pattern is exactly as the coil diameter increases. With the new slitting line, Grillo-Werke is ideally equipped for the future.