Cutting fluids

Cutting fluids, also known as machining fluids, play a very important role in modern machining processes. The main functions of a cutting fluid are: 

1. First, it must act as a lubricant and reduce friction, thereby decreasing the heat generated during the cutting process.
2. Since heat caused by friction cannot be completely eliminated and often cannot even be significantly reduced, the cutting fluid must also work as an effective coolant.
3. Finally, it should act as an anti-weld agent to neutralize the tendency of the material being cut to weld to the tool under conditions of heat and pressure.

Cutting Fluid as a Lubricant

For a cutting fluid to perform effectively as a lubricant, it needs to create and maintain a strong protective film between the surface of the tool and the metal being cut. The presence of such a film ensures smooth movement of the tool on the chip. In addition to reducing heat, proper lubrication decreases tool wear rates, especially during the machining of hard and ductile metals. 

Cutting Fluid as a Coolant

If a cutting fluid effectively carries out its lubrication function, the issue of removing heat from the cutting tool and chip during operation becomes minimal. However, cooling remains an important task. For this task to be performed effectively, a cutting fluid must have high thermal conductivity so that the maximum amount of heat can be absorbed and removed per unit volume of fluid. 

Why Water Cannot Be Used as a Cutting Fluid

Water, with its high thermal conductivity and specific heat capacity, is an excellent coolant, but its lubricating property is almost zero. Furthermore, water quickly causes corrosion of machine parts and components. It cannot facilitate smooth motion of machine components or reduce friction in the cutting zone. Additionally, water is ineffective in evenly spreading over metal surfaces, limiting its ability to absorb heat effectively. 

Soluble Cutting Fluids

Soluble cutting fluids, or water-soluble fluids, are special lubricants and coolants mixed with water for use in machining operations. These fluids play a vital role in metalworking processes such as cutting, turning, grinding, drilling, and milling because they enhance productivity, extend tool life, and provide effective cooling and lubrication. 

In these fluids, water acts as the primary carrier, helping to dissipate heat, while added chemicals improve lubrication and prevent issues such as corrosion or bacterial growth. Water-soluble cutting fluids are typically used in the following operations: 

1. Heat Management: These fluids dissipate the heat generated during metalworking processes, preventing thermal deformation or loss of dimensional accuracy.
2. Lubrication: They reduce friction between the tool and workpiece and minimize wear on cutting surfaces.
3. Chip Removal: They clean and clear chips and residues during operation, keeping the tool and workpiece clean.
4. Corrosion Protection: They contain inhibitors to prevent corrosion of metal surfaces from moisture contact.

Types of Soluble Cutting Fluids 

Water-soluble cutting fluids are primarily classified into mineral-based fluids and synthetic fluids. Each type serves similar purposes but differs in composition, performance characteristics, and applications. 

1-Mineral-Based Water-Soluble Cutting Fluids

Mineral-based cutting fluids are composed of mineral oils as one of their main components, along with emulsifiers. When mixed with water, these fluids form an emulsion (often referred to as “milky emulsion”). Due to their excellent lubricating properties, these fluids have traditionally been used in machining processes. 

Key Features: 

– Contains refined mineral oils as the main ingredient. 

– Forms a milky white emulsion after mixing with water. 

– Strong lubrication reduces tool wear significantly. 

– Suitable for applications requiring high-pressure machining or heavy cutting. 

– Commonly used in industries such as automotive and aerospace, where demanding conditions require exceptional lubrication. 

Advantages: 

– Excellent lubrication properties for smoother cutting operations. 

– Lower initial cost compared to synthetic fluids. 

– Effective in processes subjected to high mechanical pressure. 

Disadvantages: 

– Residues from mineral oils may lead to bacterial growth, unpleasant odors, or skin irritation. 

– Often less environmentally friendly. 

– More prone to oxidation and early degradation. 

2-Synthetic Water-Soluble Cutting Fluids

Synthetic fluids lack mineral oils or petroleum derivatives. Instead, they use chemical compounds like glycol, esters, or other synthetic lubricants. When mixed with water, these fluids form transparent or semi-transparent solutions, which make operation monitoring easier. 

Key Features: 

– Composed of synthesized chemical compounds, without mineral oils. 

– Forms clear or semi-clear fluids when mixed with water. 

– Optimized for high-performance applications requiring effective cooling and minimal residue. 

– Widely used in industries such as electronics and precision machining, where cleanliness is crucial. 

Advantages: 

– Highly effective heat dissipation due to the absence of oily components. 

– Minimal residue ensures clean workpieces and reduces cleaning time for tools and equipment. 

– Eco-friendly and biodegradable (depending on formulation). 

– Resistant to bacterial growth, enhancing fluid lifespan and reducing unpleasant odors. 

Disadvantages: 

– Typically, more expensive than mineral-based fluids. 

– May provide less lubrication in some applications compared to mineral-based types. 

Applications of Mineral vs. Synthetic Cutting Fluids

Both mineral-based and synthetic fluids are used in various industries depending on their specific needs. Mineral-based fluids perform better in heavy-duty operations requiring high lubrication, while synthetic fluids excel in providing superior cooling performance and cleaner operations in precision machining. 

The choice of cutting fluid depends on machining conditions, lubrication and cooling requirements, costs, and environmental concerns. 

Conclusion

Selecting the right cutting fluid is as crucial as choosing the right tool. Choosing the appropriate cutting fluid for metalworking operations can significantly impact machine performance and product quality. By using the right cutting fluid, you can reduce unexpected downtime, increase tool and fluid life, enhance productivity, and lower production costs per unit. 

At Eriss Kimia Pars, we offer soluble cutting fluids in two grades: synthetic and mineral, and we can help you select the right fluid for your specific application. Additionally, we can customize the product according to your industry needs with the support of our experienced and strong research team.