Check out these 3 simple tests to help you match your cutting fluid choice to your water supply.
Cutting fluids are an absolute essential in engineering workshops and although there are choices such as direct-application lubes or undiluted misting oils, the vast majority of operators still use a water-soluble flood coolant. Whether you go for a mineral, semi- or fully synthetic formulation, by far the largest component of your flood coolant is going to be water, so it pays to have an understanding of what to check for in your supply.
Does it really matter?
Well, whatever your supply, it might be clean but it will definitely not be pure. 100% pure water is so good a solvent that it picks up all sorts of chemicals from anything it comes into contact with, so much so that if you were to drink absolutely pure water it would probably kill you as it would quickly leach essential minerals from your body tissue! Your water supply will have its own unique combination of absorbed chemistry that it’s acquired on the way to your tap. Clearly then (no pun intended) not all water supplies will have the same properties, and this should be a factor when choosing the best cutting fluid so you really should check it, or have it checked for you.
What to Look For
There are certain properties of the water that may influence which cutting fluids would work best for you. Select the headings below to see more about each of these 3 easy tests.
Bacterial Load: As you probably know, flood coolants can get infected with all sorts of organisms, often resulting in bad odours, loss of cutting fluid performance and potential staff health problems. Unfortunately, this is somewhat inevitable with fluids circulating around people and machinery, but you can at least be aware of how much your water supply may encourage infections by checking its bacterial load. A dip-slide test will show if your water has a natural tendency to encourage infection, in which case you should consider coolant choices with higher infection resistance or more active biocide content, and maybe consider implementing a regime of biocide treatments and other maintenance to mitigate the risks.
Water Hardness: You should also check out the hardness of your supply. We are generally quite fortunate in New Zealand in that the range of water hardness is fairly narrow when compared to that of other countries, but there is still enough variance to make it worthwhile checking as some cutting oils are better suited to certain hardness ranges.
Test strips are used to check out the hardness of your supply. Knowing the hardness of your water supply allows you to ensure your cutting fluid choice is optimised in this respect. If you have higher water hardness, it’s more likely to encourage corrosion and that’s not ideal for your expensive machines, so ensuring you get a cutting fluid that can mitigate this effect, in other words one that is formulated to include corrosion-protection additives that are suitable for harder waters, is a very good idea.
Acidity (pH value): The other essential consideration for cutting fluid selection is acidity, or pH reading. New Zealand's water supply generally falls between pH 6.8 and 6.0, making it slightly acidic (anything below 7.0 is acidic, above is alkaline). Although generally falling in quite a narrow range, some NZ supplies have been recorded as low as 4.5pH. Quite acidic water is a very good solvent, naturally absorbing minerals and metals on contact, making for a more appealing environment for bacteria than neutral water as the dissolved chemicals provide a source of nutrients.
Simple test strips give a reasonable indication of the pH of your water, a digital pH meter provides greater definition and accuracy. Cutting fluids are typically slightly alkaline when diluted for use and ensuring a cutting fluid concentrate will achieve this with your water supply will help maximise stability and sump life.
Summary: Your water supply is fundamental to how your diluted cutting fluid performs and plays an important part in providing the cooling and lubrication you need. Ensuring that the product is best suited to the water will give you the greatest chance of maximising your return from the coolant costs. If you are unsure of the properties of your water supply, or if your current cutting fluid supplier is unable to provide test readings, get in touch with our experts today and we can help you make the best choice for your workshop.
