Hot Extruded Guide Rail Profiles for Pile Drivers
Some improvements come from adding a step, others from proving one is unnecessary. The guide rails that control the vertical travel of a drill head on a leader pile driver had already moved from a fabricated assembly to a hot extruded and cold drawn section. Asked in 2020 to cut processing further, Montanstahl optimised the extruded pre-shape and demonstrated through testing that the profile already met the required tolerances and radii straight from extrusion. The drawing pass was removed, and the section is now supplied in lengths from 2,000 to 12,000 mm at a rate of 30 tons per year.
Three Generations of the Same Guide Rail
In the construction machinery sector, guide rail profiles are what keep the vertical movement of a drill head precise on a leader pile driver, so the accuracy of the rail translates directly into the accuracy of the pile. These profiles used to be made by welding two angle sections together, a route that is labour intensive and expensive and that carries additional quality checks and structural inspections, since every weld along a load bearing guide has to be verified. In 2014 the customer adopted a different solution, a hot extruded profile finished by cold drawing, which improved performance and consolidated the rail into a single piece. By 2020 the objective had shifted again, this time towards reducing the machining still required downstream, which prompted the search for a more efficient way to produce the same shape. Equipment of this kind sits in the building and construction sector, where machine availability on site is what the whole schedule depends on.
Fewer Steps Without Losing Tolerance
The brief listed five points. Processing on the profile had to decrease and the production cycle had to speed up, two objectives that usually pull against the third, which was that the section still had to hold very tight tolerances on a special geometry. The rail combines a flat mounting base, a raised running head and a large longitudinal bore through the body, so material has to be placed accurately in three separate zones of the same cross-section. Supply lengths had to run from 2,000 mm up to a maximum of 12,000 mm, which puts straightness under pressure at the top of the range, and the volume had to cover 30 tons per year of manufacturing and delivery. The question underneath all of this was whether the cold drawing pass added at the previous stage was genuinely doing something the application needed, or whether it had become part of the specification simply because it was there.
Application Context
Montanstahl optimised the hot extruded pre-shape so that it satisfies the requirements of the application using the extrusion process alone. Testing confirmed that cold drawing was unnecessary, because the profile already met the tolerances and the radii specified, and the result was verified rather than assumed, in line with the dimensional checks built into Montanstahl quality management. Removing that step cut cost and lead time without touching performance, and the customer now receives the rail in lengths ranging from 2,000 mm to 12,000 mm, covering an annual demand of 30 tons. Carbon steel S355J2 provides the strength the guide requires while remaining straightforward to weld and machine in the customer’s own assembly. Sections of this kind are developed as special profiles in carbon and stainless steel, and questions on which production route fits a given geometry are answered in the technical Q&A.