An apparatus for hardening cylindrical bearing locations on a shaft, in particular a crankshaft, in which transition radii to the adjacent shaft parts are of undercut design, is provided with a heating unit, which is connected to a power supply, and with an inductor. Data and a checksum are written to a storage device, such as a RAID array. For each successive query, the data repository abstraction layer is replaced or redefined to provide a restricted logical view of the underlying data repository.