ASTM D4627 Test Method for Iron Chip Corrosion for Water-Miscible Metalworking Fluids
8. Procedure
8.1 Make the test in a room free from corrosive fumes, away from direct sunlight, and a room temperature of 20 °C to 25 °C.
8.2 Sieve the cast iron chips (6.1) on the 18 mesh screen (5.11), rejecting the fines and any chips showing signs of rust.
NOTE 2 - Do not allow the chips to come in contact with the skin.
NOTE 3 - Store the chips in an airtight glass bottle.
8.3 Using forceps (5.10), place the filter paper (5.2) in the bottom half of a clean, dry petri dish (5.1). Place the smooth side of the paper down and the rough side up to contact the chips.
8.4 Measure 5.0 mL of diluted metalworking fluid into the dish.
8.5 Using the spatula (5.4) to handle the chips, weigh 4.0 g +/- 0.1 g of cast iron chips and sprinkle into the petri dish. Use the stirring rod (5.3) to be certain all chips are submerged, all air bubbles released, and the chips are evenly distributed.
8.6 Cover the dish with its lid and allow to stand for 20 h to 24 h.
8.7 Drain the fluid from the dish. Invert the dish on its lid and tap to remove the chips.
8.8 Rinse the filter paper with running tap water for about 5 s to remove any discoloration due to the fluid.
8.9 After rinsing, estimate the percent of the filter paper area which was stained by rusting chips. This is done by visual examination (without magnification) of the side of the paper that was in contact with the chips.
8.10 The "breakpoint" is defined as the weakest concentration tested that left no rust stain on the filter paper. This value may be used to compare the rust inhibiting properties of various fluids.
