The method is based on the increase in the cutting fluid corrosiveness as they are being diluted.
1. Equipment, materials, reagents:
2. Test preparation.
Prior to each test, rub down the working surface of the plate is with a grit paper manually or mechanically to a surface roughness of 2.5 to 0.63 µm as per GOST 2789-73. Then degrease the surface with alcohol. Do not touch the working surface of the metal.
Thoroughly stir the test working solution of the cutting fluid, dilute it 1:1 with water used to prepare the cutting fluid by dispersing the cutting fluid and water into the cylinder with 2 ml pipettes, and stir again.
3. Test procedure.
Apply 10 drops of the test cutting fluid (diluted and undiluted) to the degreased plate. The distance between the drops and to the edge of the plate shall be at least 7-10 mm.
Leave the plate with samples in the ambient air until the cutting fluid water is evaporated (approximately 30-60 minutes). Then wipe the plate with cotton wool soaked in alcohol and inspect it.
Tests shall be conducted on the two parallel plates of the same metal.
4. Test evaluation.
Working cutting fluid emulsions or aqueous solutions shall be considered to be satisfactory if there are no corrosion spots on the plate. If there are corrosion spots assess the degree of corrosion as follows (see the table).
|
Point |
Degree of corrosion |
Plate appearance |
|
0 |
No |
No change or slight loss of metallic luster |
|
1 |
Traces |
No corrosion spots (10 or more drops of the original cutting fluid) and formation of a maximum of 1-2 corrosion spots (10 or more drops of the diluted cutting fluid) |
|
2 |
Mild |
No corrosion spots (10 or more drops of the original cutting fluid) and formation of a maximum of 3 corrosion spots (10 or more drops of the diluted cutting fluid) |
|
3 |
Moderate |
A maximum of 3 corrosion spots (10 or more drops of the original cutting fluid) and continuous corrosion (10 or more drops of the diluted cutting fluid) |
|
4 |
Severe |
More than 3 corrosion spots (10 or more drops of the original cutting fluid) and continuous corrosion (10 or more drops of the diluted cutting fluid) |
If the appearance of a plate is between the two degrees of corrosion, it shall be considered to have a greater degree of corrosion. The results of parallel determinations (degree of corrosion in points) should not differ by more than one degree of corrosion. A greater degree of corrosion shall be taken as the test result.
Determining the cutting fluid concentration by refractometry
