Special Stainless Beams for Trash Rack Cleaner Arms
A trash rack cleaner works at the water intake of a hydraulic structure, clearing debris from the screens that protect the turbines and gates behind them. The mechanical arm that carries the rake has to be long, rigid and dimensionally reliable, because every attachment along it bolts to a hole that was positioned during production. For a specialist in hydraulic steel construction, Montanstahl produced special beams in stainless steel 1.4301 or 304 by laser welding, with bars up to 11.57 metres carrying more than 200 holes each, positioned within a tolerance of 1 mm.
Hydraulic Steel Construction and Components That Cannot Fail
The customer specialises in hydraulic steel construction and is well aware of how much rests on the reliability of the components they build, so they demand excellent quality and consistent performance across their entire portfolio to ensure durability and long term effectiveness. That portfolio covers stop logs, gates, trash rack cleaners and custom made products developed for specific applications and requirements. For this project they were looking for a special profile to form part of the mechanical arm of a highly efficient trash rack cleaner, improving both the functionality and the performance of the machine. Equipment of this type is installed at water intakes and along dams, where it operates continuously in wet conditions and is awkward to service, which is why structural elements in hydropower and water management installations are increasingly specified in stainless steel rather than coated carbon steel.
Two Hundred Holes That All Have to Line Up
The most significant difficulty in the project was the precision and alignment of the holes along the full length of the beams. Some bars measure 11.57 metres and carry over 200 holes, and their alignment was mandatory rather than desirable, because a single hole out of position would have prevented the beam from being assembled into the finished product. Over that distance the problem compounds, since welding a long section introduces thermal movement, and a reference taken at one end drifts by the time the far end is reached. The second difficulty was organisational. The beams come in similar lengths but with different hole combinations, so bars that look alike on the shop floor are not interchangeable, and a mix-up during production or packing is as damaging as a dimensional error. Both challenges point to the same requirement, which is a process that keeps the bar stable while every feature is placed against one common reference.
Application Context
The technical team planned the production sequence so that each beam met its own specific combination of holes and length, treating the hole pattern as part of the product definition rather than as a later operation. The laser welding machine minimised material distortion during assembly of the section, and that stability is what made it possible to position the holes within a tolerance of 1 mm across the full length of the bar, improving both the quality of the part and its behaviour in service. Six different lengths of special beams were produced, each with its own set of mechanical operations, to match the requirements of the project. Sections of this type extend the Montanstahl range of stainless steel beams towards fully custom geometries delivered ready to assemble, and questions on lengths, hole patterns and tolerances are answered in the technical Q&A.