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Choosing the appropriate physical and chemical properties is not the only factor to consider. The final product may have unique and intricate formulations that are not applicable to all situations. Yet, it is still necessary for additive manufacturers to benchmark the performance of a selected fatty acid source through application testing. While not a perfect parallel, application testing is intended to challenge a product under conditions such as those experienced in a machining environment.
acid offering demonstrate similar fluid efficiency and lubricity as illustrated in Figures 3 and 4. Likewise, both TOFA products and the low rosin fatty acid demonstrate similar fluid efficiency and lubricity as illustrated in Figures 5 and 6.
Figure 3: Fluid Efficiency of high rosin mixed acid.
Figure 1: Physiochemical properties of high rosin mixed acid. Figure 4: Tapping torque lubricity curves of high rosin mixed acid.
Figure 2: Physiochemical properties low rosin fatty acid. Figure 5: Fluid efficiency of low rosin fatty acids.
In this example of evaluating such products for the metalworking fluid market, emphasis was placed on showing similar performance in lubricity and corrosion resistance in a medium oil, semi-synthetic formulation. To test lubricity, the tapping torque method was selected following ASTM D8288: Standard Method Comparison of Metalworking Fluids Using a Tapping Torque Test Machine. This method is designed to evaluate the relative tapping torque performance of a metal removal fluid. Lower torque or higher fluid efficiency indicate improved lubricity or better machining characteristics. Each metalworking fluid was diluted to 5% in synthetic hardwater and tested on a 6061-aluminum bar. The fluid efficiency was calculated with a control fluid containing no fatty acid. Both DTO products and the high rosin mixed
38 LUBE MAGAZINE NO.176 AUGUST 2023
Figure 6: Tapping torque lubricity curves of low rosin fatty acid.
Corrosion resistance was established by testing the same medium oil, semi-synthetic formula diluted to 5%, 2.5%, 1.0%, and 0.5% in synthetic hardwater following ASTM D4627: Standard Test Method for Iron Chip Corrosion for Water Soluble Metalworking Fluids. The test is designed to act as a guideline in determining the ability of a water-diluted metalworking fluid to prevent or minimise rust under specified conditions. From Figure 8 it is apparent
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