During floor material removal, some units were found to have small areas of corrosion and pitting of the extruded aluminium floor planks and a means of addressing the issue was sought. One proposal was to machine small, stepped holes in the floor and bond patches in place.
In order to test whether the patches could withstand the loading requirements, equivalent to 90kg/cm2, sections of the floor plank extrusion were required. As no leftover extrusions from manufacturing were available CV was approached to provide equivalent sample pieces. The specification required that the samples matched the train floor in its current condition as closely as possible, the rolling stock being 30 years old.
The flooring section was reverse-engineered in SolidWorks from the original manufacturer’s drawings and 200mm long sections were wire-eroded from solid 6020 grade aluminium to replicate the age-hardened condition of the train floor.
Several different hole profiles were trialled to cover all the possible patch requirements and a number of prototype patches were machined.