In machine design, the cutting fluid mainly used for machining low strength steel is?

The selection of soluble oil as the correct choice for cutting fluid in machining low strength steel is grounded in its unique properties that enhance the machining process. Soluble oil is a mixture of mineral oil and water, which makes it versatile and provides both lubrication and cooling during cutting operations.

This type of fluid is particularly effective for machining applications because it facilitates heat dissipation, reducing the temperature of the cutting edge and workpiece while also minimizing tool wear. The emulsification of oil in water helps in creating a stable film that reduces friction and prevents galling or welding of the tool to the workpiece.

Moreover, soluble oils can provide good corrosion protection, which is beneficial for maintaining the integrity of both the tooling and the machined surfaces, especially when dealing with low strength steels that can be prone to rusting.

In contrast, other fluids like mineral oil may not provide the same cooling properties due to their low heat conductance when used alone. Alcohol-based fluids are generally not as effective for machining operations because of their evaporation characteristics and may not provide sufficient lubrication compared to oils. Water-based lubricants can offer good cooling but might lack the necessary lubrication properties that soluble oils provide, making soluble oil the optimal choice for this scenario.