Do we need to test cutting fluid?
What are they?
Cutting fluids or metalworking fluids (MWF) are liquids used as a coolant and lubricant during metalworking and machining processes. There are many methods of delivering the MWF to the work piece; flooding, spraying, dripping, brushing, etc. Fluids are often contained in a sump from where it is pumped to the tool, caught and recycled.
Safety concerns
Exposure to MWF is associated with cardiovascular disease, dermatitis, acne, allergy, bronchitis and asthma. The danger arises when workers are splattered or splashed by the fluid or when the mist is inhaled or settles on the skin.
The risks are particularly associated with degradation of the substance over time, fungal growth and the development of a biofilm. Fortunately, there are basic steps which can be taken in-house to keep the fluid in good condition.
Tip. By maintaining the quality of the MWF according to the manufacturer’s recommendations, you minimise the risk to health. The first stage in managing this risk is therefore to familiarise yourself with these instructions.
What about testing?
You should have a routine for daily and weekly inspection and testing of your MWF systems. It’s not complicated, and it’s something that anyone with common sense can do (see The next step ).
Tip. Your daily checks should cover odour and appearance. Check the reservoir for changes in colour or clarity, foaming, contamination by oil/ swarf, or separation of the liquid. Look for obvious signs of biofilms on the surfaces of the sump or filters.
Tip. Review tramp oil weekly. This is a contamination oil which can come from coatings on the material being machined or hydraulic oil from the machine itself. It can be identified by discoloured patches on the sump surface or discolouration of the MWF. You’re looking for this being less than 2% of total volume.
Tip. If a machine is not in regular use, carry out a weekly test run in order to keep the liquid moving to prevent stagnation.
Tip. Check filters are clean and carry out visual checks for build up of metal fines or swarf in the sump and supply lines.
Tip. Check that your system is operating within the supplier’s recommended temperature range (as a guide, 30o C is a usual maximum temperature).
Tip. Test using dipslides which can detect live bacteria, fungi and yeast as “colony-forming units” (CFU). Dipslide results above 10,000 CFU/ml indicate a level of bacteria requiring action. This should be completed weekly.
Tip. Use pH test strips or a calibrated pH meter to check the pH. Also use a refractometer (a small hand-held device which measures light refraction) to check you have the correct concentration of product. The manufacturer’s instructions for your MWF will tell you what results to expect and what to do if they’re out of range.
For an MWF checklist, visit http://tipsandadvice-healthandsafety.co.uk/download (HS 18.21.02).
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