Generally speaking, the more sensitive the cooling characteristic is to the liquid temperature, the narrower the application range of the medium is. On the contrary, the less sensitive the cooling characteristic is to the liquid temperature, the wider the application range of the medium will be. This is because, when multiple workpieces are working at the same time, they are located in different parts of the work piece, as well as different parts of the same work piece, the contact liquid temperature is not the same. Therefore, the greater the influence of liquid temperature on the cooling characteristics of the medium, the worse the performance uniformity of the heat treatment furnace workpiece will be. According to this rule, salt (or alkali) aqueous solution is applicable to a wider range than tap water. The applicable range of heat treatment oil is wider than that of water-soluble medium with the same cooling rate.
The greater the influence of the relative velocity on the cooling characteristics, the narrower the application range of the medium is. On the contrary, the less the influence of the relative velocity on the cooling characteristics, the wider the application range of the medium. This is because, during simultaneous heat treatment, the relative flow rates of the medium in contact with different parts of the workpiece and with different parts of the same workpiece are different. Therefore, the greater the influence of the relative velocity of flow on the cooling characteristics of the medium, the worse the performance uniformity of the workpiece after heat treatment. Generally speaking, the cooling characteristic of heat treatment furnace is less sensitive to the relative flow rate, while the sensitivity of tap water is greater. The heat treatment furnace mainly controls the cooling rate of the workpiece by the polymer film indicated by its adhesion to the workpiece. As long as the relative flow rate is controlled to the extent that the polymer film will not be washed away, the influence of the flow rate on the cooling characteristics is less than that of tap water.
The wide temperature range of the medium is what we want. A wide range of media can be used in a wider range to meet the heat treatment requirements of different workpieces. Tap water is used in a narrow range. Heat treatment oil is used in a relatively wide range. For PAG heat treatment medium, varieties with low turbidity point use a narrow temperature range, while varieties with relatively high turbidity point use a wide temperature range.
When an external force causes a liquid to flow, resistance between its internal molecules impedes this flow. The magnitude of this resistance is the viscosity of the liquid. Viscosity is the main indicator of the fluidity of lubricating oil. Other conditions being equal, the flow of the liquid varies with the viscosity. Different flow conditions of heat treatment furnace will further affect the cooling effect of the workpiece.
On 2018-08-08 11:45:46
