The Basics of Metal Cutting Lubricants

In the production of a great number of industrial metal goods, the use of a specialised lubricant is necessary to aid the process, this is especially true of machining and stamping processes. Here’s our guide to the basics of metal cutting coolants and lubricants.

Why are Lubricants Used?

There is a number of reasons that manufacturers employ lubricants in the production of their goods. Firstly, there’s the role of coolants. As the name suggests, these are utilised in manufacturing for ensuring stability of temperature during cutting. Not only is it desirable to avoid the metals becoming too hot, but a consistent variation between temperatures can lead to fluctuations in the cutting of the metal, which in high precision machining causes a particular problem.
The type of cutting fluids used in these processes will vary, though most are not of the ‘straight oils’ variation, as these provide the poorest cooling effect. Instead, it is more likely for synthetic fluids to be used for cooling purposes.

The use of lubricants naturally reduces the friction of machining parts, and this in turn can reduce the steady erosion of the essential parts of machinery which are in contact with cutting surfaces. The ‘working edge’ of machinery is better conditioned and longer lasting with the use of cutting lubricants. For these purposes, the ‘straight oil’ lubricants, or ‘soluble oils’ are better suited, as they provide the best lubrication between surfaces. To reduce the wear on cutting tools further, it is often the case that further additives are used to reduce the effects of pressure on tools.

What are lubricants made from?

There are a few different categories of coolants and lubricants, which have different origins depending on their purpose within the process. As discussed above, some fluids are better suited to cooling and some to lubricating to protect tools and cutting equipment from friction and high pressure. Most producers of metal cutting lubricants will manufacture a number of different solutions in this regard.

The Straight Oil type of cutting fluid, as indicated by its name, is created using non-emulsifying oils, those that do not mix with water. Whilst these provide the best lubricating qualities, they don’t cool materials as effectively. Soluble Oils, the industry’s most common solution, are oil based but will mix with water to form a solution, these are a good compromise between the lubricating qualities of the Straight Oil variety, and the Synthetic water-based fluids. Synthetic Fluids, as outlined in this useful reference, do not contain petroleum or an oil base, but have an alkaline base and are usually applied in a diluted form. With the purer Straight Oil fluids this isn’t a possibility due to the inability of the fluid to mix with water for dilution. The Synthetic Fluids transfer heat away from cutting processes the most effectively and are most commonly employed for this purpose.

We hope that helps as an introduction to metal cutting lubricants and fluids, watch this space for more information.