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How Can I Keep Machine Coolant Cleaner for Longer?
There are many factors that can affect the lifespan of CNC machine coolant, including tramp oil, bacteria, metal fines and incorrect coolant concentration. Removing contaminants is the best place to start.
Best practices for cleaning coolant
Tramp oil, such as hydraulic oil, can be removed by using disc or belt skimmers and coalescing separators. Left in the coolant, tramp oil can cause tool damage and product imperfections.
Use a refractometer to check the coolant concentration on a weekly basis. If the coolant is too weak this can lead to corrosion and microbial growth, however if it is too strong it can cause the operator’s skin to become irritated and is also a waste of coolant.
Only top up with properly mixed coolant, don’t simply top up with tap water as this lowers the concentration of the coolant and encourages bacterial growth. You can also mix with Reverse Osmosis/Deionised water to avoid the build-up of minerals.
Regular cleaning helps prolong the life of the coolant by removing metal swarf and chips that can degrade the cutting fluid. Make sure to clean the sump thoroughly when changing the coolant to remove any sludge or bacteria. You should also use a system cleaner to flush out any remaining impurities.
Machine sumps should be cleaned regularly as bacteria thrives in dirty sumps which leads to clogged pumps.
How to stop coolant from smelling bad:
- Remove tramp oil
- Don’t leave machines idle
- Filter the coolant efficiently
- Maintain good concentration levels
If tramp oil is not removed from the coolant, it can create the perfect environment for bacterial growth with leads to foul smells and a shorter fluid lifespan.
Leaving machines idle also supports the growth of bacteria, therefore it is recommended to maintain circulation and aeration.
There are different types of cutting fluid filters, so it is recommended that you choose the best one based on the metal you are cutting. Magnetic filters are great for ferrous materials, but they won’t catch non-ferrous debris. Barrier filters will collect both types, but they may also strip the coolant of its anti-bacterial additives. You can use a combination of both filter types to remove metal fines, making sure to put the magnetic filter first to prolong the life of the media filter.
If the coolant concentration drops, it won’t be as effective at lubricating and cooling the tool or preventing rust. As mentioned previously, diluted coolant can lead to foul smells caused by microbial growth. It is important not to mix different coolants as this can cause chemical reactions that create contamination.
How often should you change machine coolant?
By following best practices your coolant should last many months, but failing to do so can result in frequent changes – as little as a few weeks. It also depends on the type of machine, material and operational frequency.
By monitoring the coolant and looking for odours, foaming, tramp oil and sludge, you will know when it is time to change the coolant.
To store and handle cutting coolant safely, keep concentrates sealed and protected from sunlight, frost, and extreme temperatures. Label containers clearly, use clean dedicated mixing equipment, and always add coolant to water for a stable mix. Keep storage areas clean and prevent contact with incompatible fluids or chemicals to avoid contamination or coolant instability.
Why do I need to filter my coolant?
Filtering your coolant extends its life and decreases costs linked to fluid disposal, machine downtime and product rejects due to damaged machine parts.
Dirty coolant can also increase the likelihood of skin irritations and damage to cutting tools. Tramp oils and dirt can cause foaming which reduces the coolant’s ability to cool and lubricate, leading to overheating and increased wear on tools and machine parts.
Conclusion
Keeping machine coolant cleaner for longer comes down to consistent maintenance, correct concentration control and effective filtration. By removing tramp oil, filtering out metal fines, cleaning sumps regularly and storing coolant correctly, you can reduce bacterial growth, prevent bad odours and extend the working life of the fluid. This helps protect cutting tools, improve machining performance and reduce unnecessary downtime, disposal costs and product defects.
