Unisign Machine Tools » Dry machining versus wet machining

Advantages and disadvantages
Dry machining versus wet machining

In the world of metalworking, a distinction is made between dry machining and wet machining.
What do these terms precisely entail, and what are the advantages and disadvantages of these two methods?
Dry machining

Dry machining

Dry machining

Dry machining is a machining process in which no coolant or lubricants are used during the cutting, milling, turning, or drilling of metal. Instead of liquid coolants such as oils or emulsions, dry machining often employs air cooling or minimal quantity lubrication (MQL). This means that a small amount of lubricant or air spray is applied to lubricate and cool the cutting tool and workpiece.

Advantages

  • Lower operational costs: Dry machining eliminates the need for coolant, resulting in reduced expenses for purchasing, storing, and disposing of these fluids.
  • Environmentally friendly: Dry machining reduces the use of chemicals, potentially lowering its environmental impact.
  • Dry machining does not produce wastewater or harmful fumes that can harm the environment.
  • Reduced maintenance: The absence of coolant means less machine maintenance, as there is no buildup of dirt and sludge that can disrupt equipment operation.
  • Improved visibility: Dry machining enhances workpiece visibility, allowing operators to more easily detect issues and monitor work quality.
  • No cleaning or degreasing: Because no coolants or lubricants come into contact with the workpiece, there is little to no need for post-machining cleaning or degreasing.

Disadvantages

  • Higher temperatures: Dry machining can lead to elevated temperatures in both the workpiece and the tool, potentially shortening tool life and affecting dimensional and geometric stability.
  • Increased tool wear: Dry machining may result in increased wear on cutting tools and workpieces, negatively impacting tool lifespan.
  • Limited heat dissipation: Coolants also serve as heat dissipation agents. Dry machining can generate more heat, potentially reducing tool life and diminishing precision.
  • Risk of burr formation: Dry machining can increase the risk of burr formation, necessitating additional post-processing and higher costs.
  • Limitations for certain materials: Dry machining is not suitable for all materials, such as heat-resistant alloys.
Wet machining

Wet machining

Wet machining

In wet machining, liquid coolants or lubricants are used during the cutting, milling, turning, or drilling of metal. These coolants are typically applied to the cutting tool and workpiece.

Advantages

  • Improved tool lifespan: The use of coolants helps dissipate heat, extending the life of cutting tools.
  • Enhanced surface finish: Coolants aid in reducing vibrations and improving the surface finish of the workpiece.
  • Better chip and waste material removal: Coolants also play a role in chip and waste material evacuation, contributing to a more efficient machining process.
  • Higher process reliability: Coolants maintain temperature control of the cutting zone, leading to greater process reliability.

Disadvantages

  • Costs: The use of coolants results in additional costs for their purchase, storage, and disposal.
  • Environmental risks: Wastewater generated during wet machining may contain potentially harmful chemicals. Proper treatment and disposal of the coolant can mitigate environmental risks.
  • Health risks: The vapors and aerosols produced by coolants can pose health risks to workers if not managed properly.

Choice for dry or wet

The choice between dry machining and wet machining depends on various factors, including:

  • The material being machined
  • The type of machining operation
  • Desired surface finish
  • Desired product quality

It’s essential to make an informed decision based on the specific needs of the machining process. Importantly, dry machining may not be suitable for all metalworking applications, and in some cases, the use of coolants may be necessary to control heat generation and extend tool life.