Composite Steel Profiles for Vibrating Waste Separation Grids
Vibration finds every weak joint eventually. A company operating in waste treatment kept losing MIG welded joints on the profiles supporting the vibrating grids inside its sorting machinery, where the load never settles and the cycles never stop. Montanstahl developed a composite profile instead, laser welding a custom hot rolled anchoring guide to a laser welded tube, a geometry that standard methods cannot produce. The hot rolled section was made directly to the installed length of 6,300 mm, and the first order covered 277 bars, or 26.5 tons, in S355 carbon steel.
Cascading Separation and the Structure That Carries It
Structural profiles in large waste separation plants take heavy mechanical stress, because the operations they support are highly dynamic by design. The customer works in waste treatment and needed a composite profile for the filtration systems inside their sorting machinery, where the role of the section is anything but secondary. It carries the large vibrating grids that separate waste by size, letting smaller fragments drop through the first screens while larger pieces travel onward, which produces the cascading separation the plant depends on. The whole assembly runs under continuous vibration, and that is exactly where the previous solution had been failing, since the MIG welded joints holding the customer’s own fabricated profiles were cracking in service. Equipment in the machinery and plant engineering sector often reaches this point, where the limit is not the material or the design but the joint between the parts.
A Joint That Survives Vibration and Two Technologies in One Bar
Three difficulties defined the project. The first was weld strength, since the joint had to be sound enough to rule out cracking under vibration, which meant addressing the root cause of the previous failures rather than reinforcing around them. A MIG weld deposits filler in a wide bead with a broad heat affected zone, leaving residual stress and a geometric notch precisely where a fatigue crack prefers to start. The second was combining hot rolling and laser welding into one functional component, two processes with different tolerance classes and different surface conditions that nonetheless have to meet along a single interface. The third was dimensional, because the installation required an exact length of 6,300 mm and the accuracy could not be sacrificed to get it. The drawing also mixes grades, with the rolled guide in one steel and the body in another, so the joint has to work across that boundary as well.
Application Context
The answer was a composite profile, built by laser welding a custom hot rolled anchoring guide onto a laser welded tube, which produces a cross-section that no single standard method could deliver. Rolling shapes the guide with the undercuts and seats the grid fixings need, while the tube contributes torsional stiffness at low weight, and laser welding joins them with a narrow, deeply penetrating seam and very little residual stress, giving the structural integrity required to withstand continuous vibration and resolving the cracking the customer had seen with the earlier MIG welds. The hot rolled section was produced directly to the 6,300 mm installed length, so the bars arrive ready to fit with no cutting or adjustment on site, and the first order covered 277 bars totalling 26.5 tons in S355 carbon steel. Composite and hybrid sections of this kind are developed as special profiles, with the options set out in the technical Q&A.