Glossary of solubles

Soluble or soluble oil

New product in concentrate form, which, when diluted in water to the recommended concentration, forms a solution or emulsion that can be used for metalworking. The technology differs from whole oil, which is intended to be used as is.

The world of metalworking …

Machining or metalworking

Metalworking is a generic term used to describe the shaping and dimensioning of a metal component through specific operations.

Machining is a set of operations designed to manufacture metal parts by removing material and cutting the metal. Metalworking is also possible by deformation (no material removal, but modification of the metal’s shape), or grinding (material removal by abrasion). The use of soluble oil is very common in machining and grinding, but much rarer in forming.

Machining costs

Machining costs cover all the costs associated with carrying out machining operations: materials, tools, machines, lubrication, maintenance, etc. Although lubricants are often associated with low expenditure, they can have an impact on many other cost items if they are not used to optimum effect.

For example: excessive tool consumption, a high scrap rate or increased destruction costs due to frequent oil changes. Regular analysis of “soluble” lubricants can therefore have a positive impact on reducing machining costs.


The hydrocyclone is a device designed to remove solid particles from the machining fluid (chips and micro-chips). It is based on the principle of separation by centrifugal force. This is not filtration in the true sense of the word, which uses a particle trapping principle.

The world of the laboratory…


Refractometric analysis is a quick and easy way to check the concentration of a soluble product. It is based on the principle that light is deflected to a greater or lesser extent as it passes through the liquid, and this is directly related to concentration.

It requires the use of a refractometer and knowledge of a specific refractometric coefficient for each product.


The term micro-organisms refers to a group of living organisms not visible to the naked eye.

Bacteria, yeasts and microscopic fungi naturally present in the environment can find conditions favorable to their development in soluble oils. Controlling the presence of these micro-organisms in soluble oils helps limit their undesirable effects.

Solubles and risks…

Health risk

A health hazard is an immediate or long-term risk that poses a direct threat to people’s health, requiring an appropriate response.

With regard to the use of soluble machining oils, there are health risks for operators. In fact, when these fluids come into contact with the skin, they can cause skin irritation, eye irritation, allergies, respiratory tract irritation and long-term adverse effects. They can also cause toxicity to aquatic organisms and the environment. It is therefore necessary to take precautions to monitor the evolution of these fluids in service.