Scale shafts are used as the reference element in linear measuring devices and as guiding shafts in glass and woodworking machinery. Because the shaft works as both a measuring datum and a sliding surface, diameter consistency, straightness and surface finish decide the service life of the whole assembly.
Production starts from hot rolled or drawn bar stock. After sawing to length with machining allowance, the shaft is rough turned on a CNC lathe, leaving 0.4 mm stock on the diameter. Quenching and tempering follow, then straightening on a press with dial indicator feedback. Cylindrical grinding removes the stock in two passes, and the final pass runs at low feed to reach Ra 0.4 without burn marks.
Hard chrome plating is applied when the shaft works in a wet or dusty environment, such as glass washing lines. Nitriding is preferred where dimensional stability matters more than corrosion resistance. After finishing, each shaft is cleaned, oiled, wrapped in anti-rust paper and packed in wooden cases for batch orders.