Rail grinding for the 21st century – taking a lead from the aerospace industry

Abstract

Rail grinding is a key maintenance activity for Network Rail. It is performed at night through possession of the track, so process speed is critical. Increasing the metal removal rate (MRR) of the rail grinding operations would be a way to improve the time taken for this operation. The aerospace industry has recently seen advances in grinding technologies that have increased MRR. This work was aimed at assessing their best practice and its application to rail grinding operations. Current Network Rail grinding operations include preventative and corrective re-profiling of the rail head. The majority of work performed in the UK is preventative re-profiling with current train speeds ranging from 1 to 10 mile/h. Opportunities exist to increase train speed and improve the productivity of this operation through the use of more advanced grinding technologies. The most relevant aerospace technology is high efficiency deep grinding (HEDG). This approach uses: a high surface speed of the grinding wheel, superabrasive tooling, and high workpiece feed rates to remove material quickly from the cut-zone. Productivity improvements were identified by applying theory on power requirements (by assessing the specific grinding energy) and chip thickness of the grinding process. Computer CAD/CAM modelling was also performed to assess the effect of changing grinding techniques on potential gouging of the track infrastructure and/or interference with example trackside obstructions. The work concluded that opportunities do exist to improve the current productivity of grinding operations. Utilizing HEDG technology theoretically provides a 100% train speed increase (utilizing the same power available with the current setup) for preventative re-profiling. This requires the application of high surface speeds of the grinding wheel and superabrasive technology. Further increases in train speed require increased spindle power. The chip thickness experienced by grinding grains is reduced for a peripheral grinding setup and high wheel surface speeds that is beneficial for wheel wear. The application of HEDG technology cutting on the periphery of the wheel provided optimum conditions during CAD/CAM simulation to avoid rail gouging, and any potential collision of the grinding stone with modelled trackside obstructions.