FRANK 540 is used at a temperature of 500-600°C for quenching parts previously heated in the FRANK HSX bath. It gives minimum distortion and less risk of cracking than when oil quenched. The parts are soaked in the bath just long enough to reach its temperature and are afterwards cooled in air. They are subsequently tempered in FRANK 540. High-speed steels are tempered preferable twice for a minimum of 1 hour each with an air cool between. The tempering temperature will be in the range of 520-570°C.