The Most Common Problem of Cutting Fluid:FOAM

The Most Common Problem of Cutting Fluid:FOAM

The most common cutting fluid problems encountered by manufacturers (users) typically fall into the following five areas: foam, corrosion, residues, odor and dermal irritation. Most metal cutting fluids, in addition to cooling and lubricating which also have good cleaning properties to help keep machines clean. However, they also foam when agitated.

As a result, foam in oil is an issue which is typically considered to be an undesirable property in a metalworking fluid. The basic cause is entrained air within the fluid caused by mechanical or chemical processes; include the quality of the water used for mixing, and the degree of agitation in the system. You can get rid of foam in a coolant tank temporarily by adding defoamers, but some defoamers helps to emulsify leak oil, which is food for bacteria. Therefore, you should always try to find what causes the foam.

Check Coolant Tank for Machine

If the tank level gets too low the pump will thrash the coolant and essentially "spray foam", and many times the cause for excessive foam. Obviously, if the chip tray gets too full and coolant is foamy it will overflow the basket.

Another, high pressure and agitation, sharp bends in the return lines, "waterfalls", high flows and high discharge pressure may cause unnecessary movement of the liquid. This can usually be improved with relatively simple redesigning of the system.

Foam is especially common in smaller sumps, where all changes happen faster. Therefore, the particles and swarf (such as turnings, filings, chips or shavings) cannot be allowed to accumulate at the coolant tank because it may hamper the access to the machine, and cause foam easily. Therefore, cleaning machine regularly will be necessary.

Check Temperature for Machine

A high temperature may lead to foam in some synthetic fluids Temperature, primarily because of its effect on viscosity which may promote foaming. It is also an important factor in foam stability.

Water Quality

If the water that you use for production is too soft for the metalworking fluid, there will be a lot of foam when a system is newly filled. Over time, the hardness of the water increases as water evaporates and foam problems are reduced.

Check Cutting Fluid

To find out, place some fluid from the sump in a clear container. Shake it well for 10 seconds to create foam in the container, and then observe the behavior of the foam. If there is little or no foam and/or it dissipates quickly, the problem is mechanical. If there is a lot of foam that just sits there and not reduces, the problem is a likely chemical.


Check above of all points with your cutting fluid supplier and metal working staff so that we can prevent and solve foam in cutting fluids (coolant).

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