Metalworking Fluids (MWF): Overcoming Stability Issues

Metalworking fluids (MWFs) are a family of industrial liquids used to reduce the temperature of and/or lubricate metal workpieces while they are being machined. Cutting and grinding processes can generate significant amounts of heat and friction, which can cause undesirable thermomechanical side-effects: burning, deformation, smoking, surface roughness, thermal warping, etc. If a workpiece burns it may be unfit for downstream application, while off-gases and smoke represent a respiratory health risk for personnel. The thermomechanical drawbacks of conventional metalworking can represent logistical health and safety issues if not addressed.

Issues with Metalworking Fluid Stability

Conventionally, emulsified MWFs are prepared by mixing different compositions and individually assessing the effects of various additives. While this method is useful in determining the impact of individual ingredients on functionality and stability, it is time-consuming and costly. It also fails to offer true quantitative insights into multiple-factor interactions between distinct ingredients or phases in the MWF under storage or use conditions.

Chemical and physical instability issues in MWFs can reduce performance and detrimentally affect product quality, and a myriad of destabilizing phenomena may affect them: blooming, coalescence of oil droplets, emulsion breaking, foaming, phase separation, etc. Although emulsion composition and component affinity are the underlying factors of destabilization, the external force also plays a crucial role in the colloidal breakdown. The force of pumping can accelerate instability mechanics, which means products will destabilize quickly in real-world use conditions. This property directly correlates to MWF efficiency.

Typically, metalworking fluids would be tested for chemical or physical instability by leaving a sample on a test bench for an extended period (days, weeks, months) and examining it for physicochemical changes. Testing for instability in actual use conditions is more challenging. Centrifugation and general agitation have been used in the past to predict mechanically driven instability, such as destabilization pumping conditions. Alternative methods of instability testing have been developed to test for at-rest stability and meet the demands of MWF development and quality control.

Turbiscan Analyzers for MWF Testing

Microtrac supplies a comprehensive range of TURBISCAN analyzers for stability analysis of concentrated dispersions, including oil-water emulsions for MWFs. These analyzers help in optimizing new product formulations and assessing the effects of additives on the emulsion’s physical stability thus providing formulators with a cost-effective R&D tool for productive and sensitive metalworking fluids performance enhancement. The result: safer and more efficient products that improve metalworking efficiency, worker safety, and sustainability.

If you need any more information about performing MWF stability tests with Turbiscan products, simply contact a member of the team today.

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