Metal cutting fluid is used in metalworking and machining for different purposes, predominantly lubrication and cooling. It comes in various different forms including synthetic fluids, semisynthetic fluids, oils and soluble oils.

Synthetic fluids are made of alkaline compounds and compounds that prevent corrosion. They are used in diluted water and are the premier product in cooling. Semisynthetic fluids are a combination of soluble oils and synthetic fluids and its characteristics appear in both constituents.

Oils are used undiluted. They offer the best lubrication but poorest cooling. Soluble oils are emulsified with water and give good lubrication and cooling compared to the other products. They are the most cost effective and are therefore most widely used.

Characteristics and Functions of a Good Metal Cutting Fluid:

• The main characteristic is its ability to keep the metal and tool temperature stable to avoid destroying the metal due to high temperatures or even a fire on adjacent materials.
• It should provide proper lubrication to lengthen the life of the cutting tip and reduce the amount of heat produced by reducing friction.
• It should be able to prevent rust on the metal cutters and relevant parts.
• The cutting fluid should be safe to use and environmentally friendly to dispose of.
• It should flush pieces of metal away from the cutting area.
  The different metal cutting fluids require different application methods; these include flooding, misting, spraying, dripping and brushing. The most common and preferred method is a jet of liquid being applied to the surface being worked on.

Metal Cutting Fluid Advantages:

• Reduced chances of deformation by heat
• Longer tool life
• Ease of chip handling
• Better surface finish.