Difference Between Water-dilutable Cutting Fluid and Neat Cutting Oil

Difference Between Water-dilutable Cutting Fluid and Neat Cutting Oil

The most important requirements to be met by coolants in metal cutting are reduction of tool wear, a high-quality surface finish and economy of use. Most of factories replaced neat cutting oils with water-dilutable cutting coolants.

Water-dilutable cutting fluids are also referred to as cutting oil, coolant, soluble oil and cutting fluid. As we know, water-dilutable coolants have good cooling performance to maintain the cutting temperature within limit, and easy to clean during machining. However, there are many uncertain factors that cause pH scale and concentration spoilage. Therefore, coolant maintenance will be an important thing for operators. Water-dilutable cutting fluids are generally grouped into three major categories: soluble cutting oils, semi-synthetic cutting oils, and synthetic cutting fluids (grinding fluids)

Generally three types of water-dilutable cutting fluid

■ Emulsion Cutting Fluids

Emulsion cutting fluids are coarse insoluble phase mixtures forming oil-in-water emulsions. The emulsions are mixtures of base oil, emulsifiers, anti-wear, extreme pressure, anti-foaming additives, corrosion inhibitors, bactericides, etc. Medium viscosity petroleum-based or mixed-type mineral oils are usually used as mineral bases; their content in the emulsion can be up to 85%.

■ Semi-synthetic Cutting Fluids

Semi-synthetic coolants are metalworking fluid concentrates that contain a small amount of oil as well as synthetic lubricants and other additives. When mixed with water, they form a translucent fluid. Semi-synthetics combine the physical lubricity of soluble oils with the chemical lubricity, cooling, and cleanliness of synthetic coolants. They have higher content of emulsifiers (up to 40%) and always contain low-viscosity (3-10 mm2/s at 50°C) mineral or synthetic oils, as well as extreme pressure, anti-wear and other additives.

■ Synthetic Cutting Fluids

Synthetic cutting fluids are mixtures of water-soluble organic products with molecular dispersion. They do not contain mineral oil base or petroleum which is form a clear fluid when mixed with water. Instead, they’re formulated from alkaline organic and inorganic compounds alongside additives to prevent corrosion. They function well in their diluted form.  All of the varieties of cutting fluids, synthetic fluids offer the best cooling performance.

On the other side, neat cutting oils have excellent lubricating for light to heavy machining (such as broaching, turning, honing and drilling, etc.) which based on mineral oils and used for cutting without further dilution. They are generally blends of mineral oils and other additives. But neat cutting oils will produce oil mist and oil smoke while metalworking that causes misting and slippery conditions throughout the workplace. Speaking of which, how do we know which metalworking oils are suitable for us?  As we know, we should consider machining types and processing materials. But we can separate and defined which sort of metalworking oil we want to use.

Comparison of different cutting oils

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