Test method for main physicochemical indexes of water-based metal cutting fluids
The performance indicators of water-based metal cutting fluid can only be used after reaching certain standards. And then according to their own characteristics, applied to different processing occasions. Therefore, the determination of the various performance indicators of the water cutting fluid has become an indispensable step.
1 Method for determination of pH value and emulsification stability of emulsion
According to the test method in the standard SH/T0365-92, the cutting fluid is diluted with water according to the use condition, the pH value is determined, and the emulsification stability is observed. Weigh the test solution 5g into a stopper measuring cylinder, add tap water to 100mL for marking, cover tightly and shake well. A wide range of pH4~10 test paper is immersed in the diluent for 0.5s and taken out, and compared with the standard color plate, the pH value is obtained. The 50mL burette filled with 5% cutting fluid is placed at 15 ~ 35 ° C for 24h to observe the precipitation volume of soap or oil layer. The volume fraction of soap is not more than 2%, and no oil formation is qualified.
2. Test method for rust resistance
The rust resistance was determined by the iron filter paper test method (IP287). This method has the advantages of good repeatability, short test time, simple and fast, and filter paper retention. Figure 3.1 shows the state during the test.
Iron filings filter paper test
Experimental materials: cast iron scrap (Grade 1 gray cast iron, Φ2~4 mm), filter paper (neutral, slow, Φ70 mm), petri dish (90mm), standard template (Grade 1~5).
First of all, 2g iron filings are weighed on the filter paper, evenly spread, put into the petri dish, and the water-based metal cutting liquid of the specified concentration is poured in sufficient amount to cover the iron filings. The petri dish was covered and placed at room temperature for 2h. After removing the filter paper, the iron filings on the filter paper were removed. The rust area left by the iron filings on the filter paper was observed. Compare with the standard sample to determine the anti-rust grade of the sample.
3. Defoaming experiment method
According to the GB6144-85 standard, the 5% water-based metal cutting fluid diluent is poured into a 100mL measuring cylinder, so that the liquid level is 70mL, cover the plug, shake up and down for 1min, and the shaking frequency is about 100 to 200 times /min. Then, stand at room temperature for 10min to observe the residual foam volume at the liquid level, which is not more than 2mL.
4. Corrosion test method
According to the test method in GB6144-85 standard, the corrosion test of copper and aluminum test pieces is carried out. Main instruments and materials: constant temperature water bath, glass surface dish Φ80±2mm, absorbent cotton or medical gauze, H62 brass (50mm×25mm×3 ~ 5mm), LY12 duralumin (50mm×25mm×3 ~ 5mm). The brass and aluminum alloy test pieces (preparation of the test pieces according to SY2755-76S "Preparation method of Anti-rust Grease and anti-rust test pieces") were immersed in 5% water-based metal cutting fluid, covered with a glass cover, and moved to a thermostat with a constant temperature of 55±2℃. The copper test pieces were removed after 8h, and the aluminum test pieces were removed after 4h, and the corrosion level was determined respectively. Judging criteria: Aluminum test pieces according to one, two, three, four four levels of assessment, one bright, two lost light, three light rust, four heavy rust, one, two qualified. Copper test pieces are also rated according to one, two, three and four levels, one bright, two slightly uniform discoloration, three medium discoloration, four heavy discoloration, one and two are qualified.
5 Storage stability test method
According to the method in GB6144-85 standard, 50mL concentrated liquid was placed in a 100mL stopper, then placed in a constant temperature drying oven at 70±3℃ for 5h, removed and cooled to room temperature at 15-35 ℃ for 3h, then placed in a low temperature refrigerator at -12 ±3℃ for 24h, removed and left to room temperature. The evaluation was carried out 1h later. If there is no delamination, phase change and colloidal phenomenon, that is, return to the original state, it is qualified.
