COMPARISON DATA BETWEEN TEST METHODS A group of foundries, as part of the AFS 4M Green Sand Committee, ran the pneumatic compactability tester alongside the 3-ram test. The results of the study were presented at the 2022 AFS Sand Casting Conference. The summary in figure 3 shows that the tests results consistently trended together and demonstrated a strong correlation. The pneumatic showed slightly higher values than the 3-ram on the same samples. It was generally agreed that the foundries could adjust their lab specifications accordingly and replace the 3-ram test with the pneumatic squeezer. BASIC TESTING BEST PRACTICES: For foundries that run a 3-ram test: - Gently rotate the cam arm to lift the weight, allow the weight to “drop” three times. Be sure not to ram the sample too quickly. Allow the weight to rise above the cam and fall from a higher than designed position as it prevents an additional force being applied to the sample. A recommendation is to pause at the “4:00” position in between rams. - Proving or Impact rings are suggested to confirm rammer energy. For the pneumatic test: - It is important to periodically check the oil/lubricant setting and addition rate as well as the pressure setting at the pressure regulator. If this is not properly maintained, the results may be incorrect, and could damage the cylinder in the machine. The oil addition rate is one drop of oil for every 3-4 cycles. - A voltage stabilizer/filter (line conditioner) is recommended to stabilize the performance of the testing equipment. For both laboratory compactability testing methods: - Sand should be struck off from the center of the tube to the right and then to the left. A specimen tube should be clean and lightly lubricated every time a sample is made. - It is recommended that a small amount of parting liquid be periodically applied to the tube swab. If not, the result will be a higher compactability reading, lower Green Compression Strength, and higher permeability than if the test was properly performed. - Specimen tubes should be checked regularly for rust, pits, or excessive wear. Accurate measurement of compactability empowers foundries to make informed adjustments, enhancing green sand quality and ultimately producing superior castings. Adhering to best practices ensures the reliability of test results and contributes to the continuous improvement of foundry processes. FOR MORE INFORMATION: Krysiak, M. B., Keener, T., & Schlotta, B. (2002, February). Optimum sand testing requires reliable rammers. Modern Casting, 30–32 Dietert, H. W. (1967). The Era of Sand Testing. AFS Granlund, M. J. (1999). Understanding the Basics of Green Sand Testing Volkmar, A. P. (1970). System Sand Control by Compression vs Compactability Testing. AFS Modern Casting Staff. (1976). Determining the Compactability of Molding Sand Mixtures Rammer Method — Tentative Standard; Determining the Compactability of Molding Sand Mixtures Laboratory Squeezer Method — Tentative Standard Alagarsamy, A., & AFS Molding Methods & Materials Div. Basic Concepts Committee (4-E). (2002). Controlling Green Sand Compactability Gerth, C; Nelson, A; Snow, B; Bryant, N. “Pneumatic vs 3-Ram Compactability Testing.” AFS 2022 Sand Casting Conference, Sept 2022 Contact: MICHELLE RING michelle.ring@noricangroup.com TECHNICAL TOOLBOX ISSUE 17
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