Application of THI®F-502 PAG Quenchant

1. Concentration Control of Quenching Fluid

（1） Determination of Service Concentration

The optimal service concentration is determined based on the workpiece's material, size, shape, heat treatment equipment, and process requirements, as shown in the following table:

（2） Concentration Detection

The concentration of the quenching fluid can be detected using a refractometer. Drop the working quenching fluid onto the lens, cover the lid, and read the value. There should be a clear dividing line visible to the eye. Multiply the reading by 2.5 to get the concentration. It is recommended to test the concentration once a week to avoid unstable product quality caused by cooling rate changes due to concentration fluctuations. (For initial use, calibrate the reading: drop a small amount of tap water onto the lens; the reading should be 0. If not, use the screwdriver provided with the small box to adjust the screw under the rubber cover. Generally, it is calibrated before leaving the factory.)

As the quenching fluid may be contaminated to varying degrees during use, the method for measuring PAG quenching fluid concentration should be adjusted accordingly to maintain consistent quenching and cooling effects. For newly prepared quenching fluid, use a refractometer to test the concentration. For quenching fluid that has been used for a long time and is heavily contaminated, use a cooling characteristic tester to measure the cooling rate, then convert it to the true concentration value to calibrate the daily refractive index coefficient. It is recommended that users regularly test the concentration and keep records during use, grasp the consumption law of the quenching fluid, and add the quenching fluid regularly and quantitatively.

Our company maintains records for all clients using our quenchant, providing regular complimentary testing of your working fluid. This service assists your company in implementing fine management of the quenching medium, ensuring controllable and stable heat treatment production quality.

2. Temperature Control of Quenching Fluid         

Due to the inverse solubility of PAG quenching fluid, the fluid temperature has a significant impact on its cooling characteristics. In principle, it can be used below the inverse solubility temperature (74℃) of the quenching fluid.

To ensure the quenching and cooling effect, the temperature of the quenching fluid should generally be controlled within the range of 10-50℃, with the optimal service temperature being 20-40℃. It is advisable to install a temperature controller at the quenching site to monitor the fluid temperature at any time.

To maintain the optimal service temperature of the PAG quenching fluid, the tank fluid temperature should be controlled within a narrow range as much as possible, and the temperature change before and after quenching should not exceed 10℃. Determine the temperature rise of the quenching fluid based on the heat treatment material, process, and workload, and decide whether a cooling system is needed and how to design it.

In winter, the fluid temperature is low. It is necessary to appropriately add stock solution to increase the concentration and reduce the cooling rate, and take measures to heat the quenching fluid to meet the normal service temperature. This can be achieved by placing a heater in the quenching fluid or adding red-hot waste parts, etc.

3. Process Quality Control in Production

Strictly control the entire production process of the workpiece. The performance of the workpiece after quenching fluid cooling is the final reflection of all links. Ensure that the workpiece's raw materials, pre-processing of the workpiece; heating temperature, heating time, heating method, workpiece installation method; quenching fluid concentration, fluid temperature, temperature change of the quenching fluid before and after quenching, stirring uniformity, foam volume of the working fluid; and the way, speed, and position of entering the tank, as well as the surface temperature when lifting out of the tank, meet the requirements of the workpiece heat treatment process. Establish strict control procedures for key processes in the heat treatment process to facilitate the discovery and solution of problems later.

（1） Notes on Fixture Installation

For small workpieces, use fixtures to hold them when immersing in the quenching fluid. Avoid overlapping placement in iron baskets. When entering the quenching fluid, the overlapping parts of the workpieces cannot fully contact the PAG quenching fluid, which will lead to uneven hardness and soft spots on the quenched workpieces. Try to ensure sufficient space between workpieces to contact the quenching fluid. At the same time, increase stirring during operation to enhance the fluidity of the quenching fluid to ensure sufficient hardness.

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