Cutting Fluid or Emulsion Wastewater? A Short Guide by YASA ET

Updated: Mar 15

In wastewater treatment, we often encounter various wastewaters such as from cutting fluid and emulsion. But aren't cutting fluid and emulsion the same substance? What are their main pollutants?

What Is Cutting Fluid?

Cutting fluid is an industrial liquid used to cool and lubricate tools and workpieces in the process of metal cutting, grinding and grinding. It is a type of coolant and lubricant designed specifically for metalworking processes, such as machining and stamping.

According to the composition, cutting fluid can be divided into two main categories: water-based and oil-based.

The water-based cutting fluid can be divided into emulsion, semi-synthetic cutting fluid and synthetic cutting fluid. Therefore, emulsion is a type of cutting fluid, and the composition of the emulsion generally includes:

1. Water;

2. Base oils (mineral oils, vegetable oils, synthetic esters or their mixtures);

3. Surfactants;

4. Anti-rust additives (zinc naphthenate, sodium petroleum sulfonate as emulsifier, barium petroleum sulfonate, benzotriazole, sorbitan monooleate, aluminium stearate);

5. High pressure additives (polar compounds containing sulphur, phosphorus, chlorine and other elements);

6. Friction control (friction reducer or oil additive);

7. Antioxidants.

All of these substances make cutting fluid wastewater among the most complicated wastewater to threat.

Cutting Fluid (or Emulsion) Usage

1. Lubrication

A lubricating film is formed during the cutting process by the cutting fluid, thereby it reduces the cutting force, friction and power consumption, reducing the surface temperature and tools wearing from the friction parts between the tool and the workpiece, and eventually improving the cutting performance of the machine.

2. Cooling Effect

The cooling effect of the cutting fluid is to take away the cutting heat from the tool and the workpiece through the convection and vaporization between it and the tool (or grinding wheel), the chip and the workpiece that are heated by cutting, thereby effectively reducing the cutting temperature and reducing the workpiece and workpiece. Thermal deformation of the tool, maintain tool hardness, improve machining accuracy and tool durability. Oil-based cutting fluid has better lubricating performance and poor cooling effect. Compared with oil-based cutting fluid, water-based cutting fluid has relatively poor lubricating performance and better cooling effect.

3. Cleaning Effect

In the process of metal cutting, the cutting fluid is required to have a good cleaning effect.

4. Anti-rust Effect

CNC machines, milling machines, drilling machines, sawing machines and other mechanical processing equipment must use cutting fluids for rust prevention.

The Hazards of Cutting Fluid Emulsions Wastewater

Waste emulsions and cutting fluids are hazardous wastes (Class HW09). Since the chemical composition of the emulsion mainly includes water, base oil (mineral oil, vegetable oil, synthetic ester or their mixture), surfactant, rust inhibitor (zinc naphthenate, sodium petroleum sulfonate, namely emulsifier, petroleum sulfonic acid) Barium, benzotriazole, sorbitan monooleate, aluminum stearate), extreme pressure additives (polar compounds containing sulfur, phosphorus, chlorine and other elements), friction modifiers (friction reducers or oil additives), antioxidants and other chemical components, each chemical component has different effects and hazards.

Among them, some chemical components not only bring certain pollution and impact on the environment, but also directly endanger the health of employees. In daily work, if the on-site staff often experience dry skin, cracks, redness, dermatitis, itching, dizziness, insomnia, dreaminess, shortness of breath, shortness of breath, cough, rhinitis, gastric perforation, peritonitis, kidney damage, limb weakness, memory loss, tooth erosion, chronic bronchitis, emphysema, pulmonary sclerosis and other symptoms can be actually caused by the toxic elements contained in the emulsion.

Environmental Hazardous Components of Emulsion Wastewater

Cutting fluids (emulsions) also contain a number of environmentally harmful components:

1. Anti-rust powder in anti-rust additives.

2. Zinc naphthenate in anti-rust additives.

3. Phosphorus in extreme pressure additives.

4. Chlorine in extreme pressure additives.

5. Aluminum can dehydrate the protoplasm of plant cells, and then destroy and die. Aluminum combines with pectin in the cell wall to strengthen the cross-linked structure of pectin, which hinders plants from absorbing water and nutrients.

6. Aluminum is also closely related to mineral nutrients such as calcium and phosphorus in plants. It can inhibit the absorption and accumulation of calcium and phosphorus by general plants, and also affects their absorption and accumulation of potassium, magnesium, iron, manganese, copper, zinc and other elements.

8. Zinc naphthenate is harmful to the environment. Hazardous characteristics, flammable in case of open flame and high heat, decomposed by high heat and emit toxic fumes; combustion (decomposition) products: carbon monoxide, carbon dioxide, zinc oxide.

9. Harmful combustion products of barium petroleum sulfonate: carbon monoxide and carbon dioxide, which will cause environmental pollution.

All of these chemicals make cutting fluid and similar kind of emulsions an hazard for humans, the environment and are among the most difficult wastewaters to treat, but are a necessary element of the metalworking industry.


If you have any doubts about cutting fluid and emulsion wastewater treatment, YASA ET experts have designed wastewater treatment system for many factories.

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Cutting Fluids Wastewater Treatment - YASA ET Customers' Cases

Study on the treatment of waste metal cutting fluids using electrocoagulation (

Cutting fluid - Wikipedia