Machine shops spend ten times or more money on tools for machining than they spend on coolant. Sometimes not much thought goes into which coolant is used or how it is used. In today’s market new methods of machining are being explored with tools designed to vastly increase production. Along with the “new” tools come “new” concerns regarding coolant. Today, you need to ask more than just, “which coolant is the best for the job?” but also, “what can I do to improve my total process?”
Here, we are going to explore the steps necessary for saving big money on your coolant usage, including ideas on waste disposal and how to improve your total machining process.
1. Water
All water is not created equal. Most people agree that spring water or water from a well tastes better than distilled or treated city water. Well water tastes better because it is rich in minerals. But what tastes good may be robbing you of tool life and finish.
You might think that softened water would help, but softening merely removes the calcium and magnesium from the water and replaces those ions with sodium ions. The trouble starts when those sodium ions are mixed with a coolant that contains chlorine compounds. The result? This mixture produces sodium chloride—that’s table salt—and you end up with rust problems.
If you want to save 20-30 percent on your total coolant usage, the answer is not to soften your water but instead to treat it to improve its quality.
De-ionized (a.k.a. DI) and Reverse Osmosis (a.k.a. RO) are two methods of removing water contamination and improving your total process. Your local water treatment company is familiar with both types of systems and can discuss which water process is best for your operation.
When you improve the quality of your water supply, your coolant will not only last longer but you will also realize another money-saving benefit—you will greatly reduce your coolant disposal costs.
2. Tramp oil
Tramp oil is the uninvited dinner guest that shows up when and where it is least wanted. This being the case, we can’t ignore this party crasher’s presence.
Tramp oil sneaks in from leaking hydraulics, gear and way oils, and from parts coated with oil that are ready for machining.
Tramp oil offers no advantages, only disadvantages. For example, it shortens coolant life; aids bacterial growth; interferes with rust protection and, perhaps worst of all, it prevents adequate separation of metal fines.
A common method for removing tramp oil from your coolant is with the aid of an oil skimmer. Oil skimmers come in a variety of shapes and sizes, some of which are advertised in this magazine. They vary in price almost as much as they vary in design. Regardless of which skimmer type and price you choose, an investment in removing tramp oil will always result in an improved process.
3. Metal fines
Once you’ve treated your water supply and put skimmers on all your machines, the next step is to remove metal fines. This is not the same as removing chips from the machines. There are many different mechanical devices designed into most machining centers that carry chips into a hopper for easy removal and disposal.
When we talk about removing metal fines, we are talking about removing those particles of metal that are so tiny they exist at the micron level. This will require filtration such as paper rolls or cloth bag filters. It’s most important to minimize those particles that could interfere with exceptional machining finishes. Very fine metal particles prevent tools from working at optimum performance. Machining aluminum, for example, yields aluminum chips and fine particles of aluminum. As the coolant becomes saturated with these aluminum particles, the coolant’s ability to continue to provide rust protection is impaired. The aluminum particles oxidize into aluminum oxide—the same material used as an abrasive for grinding wheels and sharpening stones. It is easy to see how this same aluminum oxide will interfere with achieving an excellent finish by getting between the tool and the work piece.
Similar problems exist when machining all types of metal. Anything you can do to improve filtration will extend coolant life. And once again, longer-lasting coolant improves your total process.
4. Concentration control
One of the easiest and least expensive steps you can take to improve coolant life and performance is to regularly monitor the coolant concentration with the use of a refractometer. Maintaining coolant concentration at a consistent level helps avoid both rust problems that arise when coolant is too weak and skin irritation issues that flare up when the coolant is too strong.
A very good quality refractometer can be had for less than $100. You will save more than the cost of a refractometer just from the first drum of coolant you use while monitoring its concentration.
5. Using the right coolant to begin with
We’ve all heard the old saying, “You have to spend money to make money.” Well, sometimes, “You have to spend money to save money.” Let me explain how this works regarding coolants.
If you go through the process of improving your water, removing tramp oil and metal fines, and even invest in a refractometer, you might still be making a mistake if you are not using a high quality coolant.
There are many different coolants available today. They vary in color, price and quality. Just as there have been major improvements in the quality of tooling available on the market, there have been similar improvements made in coolant formulations. Yes, these new and improved coolants may cost more but your added investment will reap better tool life, improved sump life, and increased operator acceptance.
I must also add that you will see improved cost-effectiveness. Let me give you some examples.
Let’s say that you are using a coolant that costs $10 per-gallon and the recommended use concentration is 5 percent to 6percent; however, you know that you will get better tool life if you run the coolant at 10 percent to 12 percent range. A new, high performance coolant that costs $15 per gallon will actually cost less to use, if you maintain the concentration at the 5 percent to 6 percent level.
Another example that must be shared is the idea of buying coolant based on cost-per-gallon. One of my salesmen came to me with a sample of a competitor’s coolant and told me his customer was paying only $6 per gallon for this coolant. Then he asked if I could make a similar product. Upon analysis of the sample I discovered that the coolant concentrate, right out of the drum, contained 80 percent water. My response to my salesman was, “Yes, we can make a coolant that is 80 percent water, but we never will!”
Look at it this way. We could very easily take a $12 per-gallon coolant and add 50 percent water. But why would we have our customers pay so much to ship water across the country?
Please consider carefully the coolants that you are buying. If the cost-per-gallon is less than $9, I can tell you with certainty, based on current raw material costs, that your coolant contains a high percentage of water. Don’t take my word for it; send a sample out to an independent laboratory for a water analysis. The best way to compare coolants isn’t by cost-per-gallon but performance. This includes longevity in the sump.
Conclusion
Using the recommendations outlined above, you could very easily save 25 percent to 30 percent on your total coolant usage. The best way to get started is to ask your current “full service” supplier to help you out. If you can’t get the answers you are looking for, find a coolant supplier you trust and I’m sure you will improve your total process.
