Do you struggle with foaming? Do you get annoyed when it covers your workpiece and overflows in the tank?
“Of course!” you might be saying, “Doesn’t everyone?”
Foaming is a problem characteristic of softer waters, which like to lather with the slightest bit of movement.
And in a country where most of the water is labelled as soft or very soft (excluding SA and some part of WA), foaming can become a major issue.
This is why water hardness is often discussed in the industrial fluids industry in Australia - it has such a big impact on the performance of cutting fluids, which means it’s crucial that you’re able to keep it in check.
Water Hardness
One of the most common causes of foaming in coolant is soft water. The lower the water hardness, the more likely the coolant is to foam.
Put simply, water hardness is determined by the amount of dissolved minerals (such as calcium and magnesium). The higher the mineral content, the harder the water. This is represented in parts per million (ppm) - Soft water is typically classified as a mineral content of below 60ppm, while hard water is classified as between 120-200ppm (anything over 180ppm is extremely hard).
This is important, because from a chemical standpoint, the lower the lower the calcium and magnesium ions, the higher the sodium ions are. And because of this, sodium formulations are often used as agents to increase the foaming characteristics of products like shampoo and hand soaps.
What does that mean for you? The softer your water is, the more likely your cutting fluid is to foam as it circulates through the machine.
Of course, this all depends on where you’re located. On the whole, Australia has soft water across the board, except for select areas in the regions and the outback, where water is typically harder.
However, if you’ve got a manufacturing plant or workshop in Melbourne, Sydney or Brisbane, your water hardness is likely going to range from 10-100ppm. Perth and Adelaide have higher averages, with water hardness ranging anywhere from 30-230ppm.
Here is a list of the water hardness of the major capital cities throughout Australia:
Adelaide: 98-138ppm
Brisbane: 100ppm
Canberra: 20-40ppm
Darwin: 31ppm
Hobart: 6-35ppm
Melbourne: 10-26ppm
Perth: 29-226ppm
Sydney: 39-60ppm
As you can see, South-Eastern states tend to have softer water, along with the Northern Territory.
One thing to note is that fully synthetic coolants (or neo-synthetic coolants) generally tend to have less foam due to their advanced polymer formulations. This means that it is much less susceptible to foam even with softer waters, making it the perfect choice for Australia.
Why should I care about foaming?
Foaming is irritating. That’s mainly because it blocks your view from the workpiece. For example, if you’re machining a part that has a hollow section, you need to get both metal working fluid and the tool into that section. If there’s foam, it’s likely going to mean that you can’t see what you’re doing properly. Not only does that mean that it could take you longer, it also has the ability to reduce accuracy, which we don’t want. On top of this, foaming and frothing causes an expansion of the coolant, meaning you can’t fill the tank as high as you would otherwise because it would overflow.
High Pressure Coolant
Another common factor that might be causing foaming, is if you’re using high pressure coolant for machining. As part of an effort to improve tool life and innovate, many machining companies are moving towards a cooling and lubricating method called ‘through-spindle-cooling’.
This is a process in which coolant comes through the spindle and directly on to the workpiece. While this can be very effective for CNC machines, it’s not suited to every type of coolant – especially those that are older.
That’s because the coolant is placed under extreme pressure by being forced out of the tip of the tool. Add to this the speed the coolant is flowing, and the fact that the tip is spinning at the same time, and you’ve got a very high-pressure environment that fosters foaming.
Some older coolants simply aren’t designed for this intensive process, causing unwanted frothing.
What can I do about it?
If you’re saying to yourself, “What can I do about foaming?” I’m glad you asked.
If you have foaming issues, the first thing you can do is check your water hardness. You can do this through a simple water hardness test kit, you can get a professional assessment on your water quality, or you can ask your water provider for the latest water quality report.
Once you’ve done that, you need to check that your coolant is compatible with that particular water hardness. If you can’t find this on the label, you’ll need to ask your supplier for the TDS (Technical Data Sheet). It will give you the recommended water hardness range. You want to make sure that you’re comfortably within that range.
Note: If you’re seeing mg/l (miligrams per litre), instead of ppm (parts per million), don’t stress, as they are roughly the same. For example, 10ppm is equal to 9.99 mg/l.
Now, if you’re well within that water hardness range, and your coolant is still foaming, you might need additional anti-foam additives. Most coolants (especially premium ones) will have anti-foam additives already, which aids in reducing the foam by causing it to dissipate quicker once the coolant has been mixed.
If your water is extremely soft, a shock treatment might not be enough to finish it. In this case, you may need to use a longer-term solution of actually adjusting the water (through filtering) in order to completely eliminate foam.
If you're still unsure what to do, you can reach out to our friendly team of specialists on 5551 4555.
