Aluminum slit strips: a precision slitting line with minimal burring enables tension-free custom cutting for coil widths up to 2,100 mm

Coil processing line requirements are ever more demanding on account of the increasing use of modern materials. High-strength aluminum – highly resilient and extraordinarily flexible – is opening up entirely new possibilities in industries like automotive and aerospace, but it’s extremely hard to process. Especially in sheet processing and assembly, precision and cut quality matter if you want to avoid failed batches. But much of the machinery introduced over the years lacks the capability to cut modern materials with enough precision due to customer requirements for thickness and width in the geometrics of the slit strip. That’s why Manfred J.C. Niemann Zentrale KG (NIE•MET) added a new Burghardt + Schmidt wide-material slitting line to its machine fleet in late 2018. The new line is designed to process particularly wide aluminum coils of 800 to 2,100 mm. And thanks to high-precision shears and a circumferential setting mechanism on the coiler, it can also set an outer diameter of 1,850 mm efficiently and accurately.

The new production hall at Manfred J.C. Niemann Zentrale KG (NIE•MET) in Bremen, Germany has been producing aluminum strips since fall 2018. “Our aluminum slit strips are 0.5 to 4.0 mm thick and a minimum of 80 mm wide. As a result, they’re suitable for a very wide range of applications,” says Managing Director Jörn Niemann. “Depending on the thickness of the material, the yield strength is 20 to 580 N/mm² and the tensile strength 65 to 600 N/mm², so it’s especially demanding having to cut them to custom sizes.” Hence, the company went looking for a machine designed for wide coils. Based on decades of positive experience, NIE•MET opted for a wide-material slitting line from Burghardt + Schmidt.

Efficient planning and production makes for timely commissioning

Having won the order, the Burghardt + Schmidt team made a site visit to establish the ideal position for the line in the production hall. The two companies have been working together for years, so Burghardt + Schmidt experts have a track record of trust built on previous projects. “Because the site is so close to the Weser river, we had to make sure the foundations were not too deep, otherwise groundwater would get in,” says Thomas Baral, Managing Director at Burghardt + Schmidt GmbH. The experts in metal cutting and leveling lines also met NIE•MET’s processing range specifications for the new precision slitting setup, with coil widths of 800 to 2,100 mm.

Thanks to Burghardt + Schmidt’s efficient forward planning and extensive existing knowledge, it delivered the turnkey line in mid-2018, right on time.

Special cutting and coiling systems for large coil diameters up to 1,850 mm

The heart of the new line is the TWIN CNC slitting shear, with a pretensioned precision roller bearing and zero backlash linear guide designed for accurate and above all stable positioning. “To meet the sophisticated processing requirements and cut strips of the required width with minimal burring, the shears have to guarantee tension-free cutting every time,” says Baral. “So when producing the line, we gave particular attention to the blade shaft in terms of precision and calibration. The installed blades are 400 mm in diameter and are assembled together with rubber-bonded spacers. This means that in one pass at a working speed of 200 m/min, depending on the material strength and thickness, the line makes no more than 22 cuts for 21cuts.

The slitting shears feature a push-off plate to guarantee rapid retooling with the four-arm tool change system outside the line. “Retooling is often complicated, but the Burghardt + Schmidt tool changer makes it much faster and simpler,” explains Niemann. “Having it in our new line gives us semi-automated and therefore faster retooling.” This speeds up workflow, thus significantly improving not only availability but also safety, because workers no longer have to position the tools in the line by manually.

User-friendly operation for high productivity and quality

For a perfect cut, you need parallel blade shafts, which is made possible through  active repositioning during the cutting process. A specially developed transfer table transports the cut strips. A deflector with roller bearings separates the strips. The recoiler is fitted with a quick-change fastener for easy mandrel changes. What’s more, a circumferential setting mechanism on the recoiler boosts line efficiency and improves operator ergonomics. “Our employees really appreciate the occupational safety improvements in terms of handling,” adds Niemann.

The central main control panel and the latest software, which is tailored to customer requirements, guarantees intuitive handling with straightforward data entry. It also has a clear, well-structured display that shows faults, line speed and other information. The decoiler and coiler feature auxiliary control panels to ensure that operators can keep an eye on the whole line. This means they can adjust and monitor all the key quality and safety parameters from different positions, ensuring smooth production despite the challenges of the material. To allow in-process quality monitoring, cameras continuously check the upper and lower surface. This means that faults are easier to identify without stopping the line and taking random samples for assessment. In this way NF metal experts guarantee fast, flawless coil throughput with precision-made strips. Baral sums up: “We’re delighted to have helped such a long-standing business partner meet its demanding quality requirements. We value NIE•MET’s confidence in our lines and look forward to working with them on future projects.”(For more information, visit www.niemet.de, www.b-s-germany.de)