Oil has a lower cooling capacity than water (especially in the low temperature stage), with a maximum difference of 28 times. In most cases, wheel forgings require rapid cooling at high temperatures to ensure hardening, and slow cooling at low temperatures to reduce tissue stress. The method of using water-quenched oil cooling in production is to take advantage of the strong cooling capacity of water at high temperatures and the weak cooling capacity of oil at low temperatures to achieve this goal.
The change in temperature has a small effect on the cooling capacity of the oil, so it can still be used as the oil temperature rises. The oil temperature in general production is between 20 ℃ ~ 80 ℃. When the oil temperature is low, the viscosity is large, and the disadvantage of uneven cooling is easy to occur. The circulation of oil has little effect on its cooling capacity. The main purpose of circulating oil or moving the workpiece up and down in production is to uniformly cool the workpiece and prevent the local oil temperature from rising too high.
The cooling capacity of air is very low (especially in the low temperature stage). The cooling capacity of flowing air and stationary air differ greatly. The cooling capacity of water, oil, and air has a certain range of limitations, which cannot fully meet the requirements of wheel forgings on different cooling speeds, so spray cooling is being widely developed and adopted.