What You Need to Know about Coolants and Swarf

The machining industry is no stranger to the words “coolant” and “swarf.” The advanced machines used in metal cutting processes usually produce waste materials in the form of mists and chips; these materials can cause serious health and safety risks for humans, fire hazards for properties and even damage to the surrounding environment.

With dangers such as these, there needs to be a clear understanding of what coolants and swarf really are.

What are coolants?

Machine Cutting

In the world of metal machining, cutting fluids can be used for a number of reasons; to extend tool life, to protect workpieces, for reducing the thermal distortion of a workpiece and for an enhanced surface finish – cutting fluids can also act as lubrication at low cutting speeds and cooling agents at high cutting speeds.

Straight oils

Not water-miscible and composed of 70-85% mineral oil, these provide the best lubrication and rust control but they have the poorest cooling characteristics compared with the other fluids.

Soluble oils

These emulsify into water and contain 60-85% mineral oil. As the least expensive fluid alternative, they are widely used as they offer good lubrication and have a great cooling capacity.

Semisynthetic fluids

These emulsify into water and comprise 5-50% mineral oil. The heat transfer performance and cost of these fluids lie between synthetic and soluble fluids.

Synthetic fluids

With no mineral oil, they provide the best cooling performance and microbial control – they also have great corrosion control.

What is swarf?

Swarf extraction

Swarf (or filings, shavings, metal chips or turnings) are waste materials removed by grinding, drilling, turning, milling or cutting tools in the machining of metals, wood, stone and other elements.

The form of the machine shavings will depend completely on the type of metals being machined. Hard and brittle metals with low strength are often discarded as small and uneven bits, while softer metals or those of higher strength may peel off as coils or ribbons.

Often very sharp and able to cause minor to serious injuries to all those who handle them, it is absolutely essential to remove them immediately before they become airborne.

Hazards of Coolants and Swarf

Health and Safety Risks

Contact with metalworking fluids in machining operations may cause irritation to the skin, eyes, nose, lungs and throat; respiratory diseases, skin diseases and even cancer have also been associated with metalworking fluid exposure. This is all because of the mist they produce, which can easily penetrate the human body through various routes of exposure. The severity of the disease will depend on the kind of fluid used, the type of infection and the duration of the exposure.

On the other hand, swarf – with most chips being razor sharp – may cause shrapnel wounds, as they often ricochet and fly more than a few metres during the machining procedure. Needle-like swarf can cause puncture wounds that may either be insignificant or severe, depending on their size. What’s more, swarf not only causes injuries to employees, it also severely damages the machinery.

Fire Hazards

The most combustible among the four metalworking fluids are straight oils, as they can easily build up heat and therefore create a mist that can cause dangerous and contaminated work conditions – the mists produced by this fluid also have the potential to be fire and explosion hazards.

Swarf can be highly flammable because of its high surface area; this is especially true of metal chips containing iron, titanium, calcium and magnesium. Furthermore, swarf stored in bins or piles may have the tendency to spontaneously combust, particularly if it is coated with metalworking fluids.

Environmental Threats

Metalworking coolants come with a high risk of environmental pollution due to their high concentrations of chemicals that are harmful to the Earth. Extensive use of these liquids can produce a sizeable waste stream which can contaminate groundwater, lakes, rivers and other water bodies. Improper disposal of these fluids can also negatively impact the environment due to dangerous metal carry-off, harmful chemical components, oil content, oxygen depletion and nutrient loading.

Metal chips have the ability to remain in the environment for a long period of time before biodegrading. This causes irreversible harm to wildlife and renders arable soil unfit for farming and agriculture.

Safety Measures for Coolants and Swarf

Be Informed

The best way to avoid any injuries and other major or minor mishaps is to always be informed. Know the machine you are working with and what it can or cannot do. Familiarise yourself with all its functions and identify the correct handling and maintenance procedures. It pays to know every little detail regarding the device you are operating.

Responsible Managers will remind employees of the necessary safety measures and it is the job of the workers to listen well and follow instruction.

Personal Protective Equipment (PPE)

Employers in the machining industry are advised to train employees on the appropriate PPE – when to wear it and how to accurately wear, remove and maintain it.

PPE for the machining industry can be used to protect employees from flying metal particles or swarf, chemicals found in metalworking fluids, high temperatures and sharp edges. For example, protective sleeves, protection goggles, chemical-resistant clothing and aprons are needed for some machining operations. On the other hand, the right gloves and safety shoes are especially important for the safe handling of swarf.

Air Cleaning Systems

For an assured cleaner and healthier workplace, nothing can compare to the work of a good cleaning system – and nothing beats Airbench in this area!

Airbench offers a range of coolant mist filters ranging in capacity from 500 to 2500 m3/hr; offering solutions to most metalworking fluid issues. Our OMF range is best for coolant mist within machine tools, while our BD blow-down bench is designed as a self-containing cleaning station; perfect for removing swarf and coolant from machined parts – place the workpiece in the cleaning area and then manually blow it down using a blowgun.

The final processing of machined parts often includes sanding and polishing. This is where our AirBench downdraught bench – with appropriate filters – can be used to efficiently capture dust from finishing operations.

Coolants and swarf have no rightful place in your working environment; it pays to consider the health and safety of each and every person involved in the machining process! Airbench knows exactly what you need – we have the necessary industry experience to effectively deliver the best cleaning solution for you and your company. For further enquiries, contact us on 01206 791191 or email us at sales@airbench.com.

More Latest

Image of 2 men working on a machine.

The Future of CNC Machining

Find out more
Image of composite waste travelling down a conveyor belt.

Composite Waste: Regulations & Solutions

Find out more
Dust hazard in the workplace

Local Exhaust Ventilation: Information for Employers

Find out more
Man breathing dust

Industry Dust & Fumes: How Dangerous are they?

Find out more

Why choose AirBench?

AirBench Ltd are the UK’s leading manufacturer of downdraught benches and cross draught extraction systems. We have more than 10,000 extraction systems in service in the UK and overseas. Along with our range of coolant mist filters and air cleaning systems, we are actively helping businesses across many industries solve their workplace dust and fume issues.


If you'd like to try an AirBench product for FREE simply book a demo and we'll bring one to you.