19 Hacks to Avert Metalworking Fluid Foul-ups and Freakouts

When machine shops and manufacturing facilities don’t pay attention to metalworking fluids, the consequences range from poor tool life to reduced metal removal and higher operating costs, Castrol application engineer Brent Morgan says.

In extreme cases, adds John Treese, director of global training for Master Fluid Solutions, machine damage can occur.

“Metalworking fluids are often the last thing shops think about,” Morgan explains. “But those who choose a good coolant and take care of it properly will enjoy much greater machining performance.”

Following are tips from the two experts on getting maximum results from cutting fluids and avoiding problems that can hurt performance and lower your bottom line.

John Treese, Master Fluid Solutions

Consider using a bucket top vacuum: “Some companies sell a ‘bucket top vac,’ a device that snaps onto an empty 5-gallon pail, transforming it into a mini shop vacuum. By holding it about half an inch above the coolant, it can effectively suck up the tramp oil, which is lighter, leaving behind the coolant and water. The collected oil is then easily transported to the disposal area. For shops that don’t have skimmers, the bucket top vac is a practical solution for managing tramp oil.”

Avoid softened water: “We generally advise against using what’s known as ‘softened water’ like that from your home water-softener system. This process exchanges sodium and chloride for magnesium, calcium and other minerals. If the system doesn’t flush properly, you could introduce salt water into your machines. This can cause steel parts to rust and is also harsh on coolant, leading to multiple issues.”

Watch out for mineral residue: “Have your local water supply checked. It might be necessary to install a reverse osmosis or deionization system, which provides water low in minerals such as calcium, magnesium, copper and the like. This type of water tends to produce fewer residues, extends the life span of your coolant, and reduces the amount of coolant used. Depending on the coolant you use, you’ll need about a quarter to 1% less chemical concentrate for every grain of hardness you eliminate, saving money.”

Pay attention to coolant concentration: “Every coolant has a recommended concentration range. Keeping it as close to the target as possible ensures optimal cutting results, the longest life span, and less staining and rusting. In fact, properly maintaining the coolant’s concentration and pH levels can help alleviate most issues people encounter with tool life.”

Use specialized pH adjustment chemicals: “We strongly recommend using pH adjustment chemicals specifically designed for the metalworking industry. Other substances, like baking soda, may contain additional components that could create other problems, such as residue in the machine sump. We also advise against using pool chemicals. These can be quite harmful, and when used in larger quantities, substances like potassium hydroxide (KOH) and sodium hydroxide (NaOH) can cause severe burns and even blindness if they get into your eyes.”

Monitor pH: “Low pH can increase fluid usage, so it’s important to keep it where it’s supposed to be. The simplest way to achieve this is by maintaining the proper coolant concentration—don’t let it get too high or too low. Most coolant manufacturers ensure that their products stay at the target pH when fluids are properly maintained, but check it periodically with a pH test strip just to be sure.”

Be careful with biocides: “Biocide use is generally unnecessary and indicates a pH or concentration issue due to poor maintenance. But if you do need one, be sure it’s formaldehyde-free, and be careful handling it. Biocides are nasty stuff and can burn your skin or cause other health problems.”

Top off machines regularly: “Top off the machine with fluid daily or whenever the coolant level drops by 10%. This makeup concentration is probably much lower than what you aim to maintain in the sump. When machining materials that generate significant heat, like stainless steel and Inconel, you’re likely to have a lot of water evaporating, thus needing to add a 2% concentration of coolant to maintain it at the desired level. However, when machining materials like aluminum, which typically produces a higher volume of chips, more coolant gets carried off. In this case, you might need to add a 3% concentration of coolant to compensate for the greater loss.”

Keep sumps clean: “It’s essential to keep sumps clean. We often joke about it, but it’s surprisingly common for workers to spit sunflower seeds and chewing tobacco into their machine, or even dump their soda or coffee into it at the end of the day. Doing so introduces sugar and other substances that feed bacteria, leading to many problems, including Monday morning stink.”

Replenish daily: “A daily replenishment strategy ensures the effective components of the coolant—the bio package, pH adjuster, buffer and corrosion inhibitors—are regularly refreshed, maintaining a strong defense against bacterial growth in your coolant system. This practice is perhaps the most significant hack for maintaining your machining operations.”

General Recommendations

There’s more. Don’t blow off parts with shop air (a thin film of coolant will help protect against corrosion). Install a tramp oil skimmer. Clean the sump regularly. Always use a proportioner when mixing coolant, especially on the makeup fluid.

Following each of these recommendations can mean huge cost savings and significant performance improvements.

If you’d like to learn more, reach out to one of these cutting fluid specialists or your MSC representative.

Which tricks have you found most helpful in getting the most out of your metalworking fluids?