Rail Surface Quality Improvements from Utilising a Novel High Speed Superabrasive Grinding Approach

Throughout the content of this PhD project the current technology utilised for rail grinding is reviewed and a novel, more efficient grinding technique for the railway industry is proposed. The current conventional method comprises resin bonded grinding stones along with low speeds and low material removal rates. Testing under laboratory conditions was performed on rail specimens to aid in the research of the technique. Several aspects of the ground specimens were analysed such as roughness, microstructure, and post-grinding performance. This verified the undesirable effect of conventional grinding on the rail material, as it was revealed that White Etching Layer (WEL) can be formed out of the grinding process which can eventually lead to the initiation of cracks and negatively affect the rail performance. Additional analysis of field ground specimens was done on a Full-Scale Testing Facility that simulates the rolling/sliding mechanisms between wheel and rail to validate the scaled post-grinding results. This further aided in identifying the problems and weaknesses of the conventional technique. Hence, upon a broader literature research, a high speed grinding technique which utilizes superabrasive material was defined as the most appropriate for the railway industry. By utilising the superabrasive material, elevated rotational speeds can be used on the grinding wheel along with higher feed rates. This will reduce maintenance times, improve the surface properties, and the overall efficiency of the process will drastically increase. Upon assessment, the most appropriate design was selected for a test rig that is able to simulate operating conditions of the grinding process as well as perform experiments at higher grinding speeds. Experiments were performed on full scale rail specimens to assess the technique and establish the methodology. Testing on full scale rails allowed the validation of the method under near real-life conditions. The ultimate goal is the implementation of the technique in the railway industry resulting in the reduction of rail damage as a consequence of the grinding process, the elimination of undesirable grinding by-products such as WEL, the decrease of the downtime for rail networks and maximising the overall efficiency and performance of the industry.