For rings occur when the cooling problem, the following measures have been taken.
1. Without changing the cooling mode, improve ferrule quenching temperature (optional upper limit temperature), to increase the steel undercooled austenite stability, thereby reducing the critical cooling rate GCr15 steel. But with the improvement of the heating temperature of the steel secondary carbides dissolve too much, causing the austenite grains grow larger, but grew up martensite hinder weakened, a large difference in hardness less the same plastic plain bearings the maximum difference HRC2, quenching, tempering occurs when tissue is still a small amount of local small block troostite exist; but also began to appear with tiny needle-like martensite at 500 times optical microscope can see the obvious needle like martensite (overheating tissue). A sharp rise in the amount of deformation hardening, diameter variation over slip from an average of less than 10% to more than 20%, the mechanical properties of the parts is relatively deteriorated.
2. Use CY-15A ball transfer uni has a faster cooling rate. Since the objective conditions in production, inevitably into the small amount of water in the tank, so that oil will gradually emulsification properties change in the course,bearings types lose a good cooling effect, leaving the quenching quality reach the desired results.