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Many think that if coolant comes shooting out when you turn on the switch that everything is operating correctly. This may be true much of the time. However, there is more to this system than meets the eye. Coolant is liquid, mist or air that keeps parts and tools cool. If the system is not functioning properly, it could eat up a large chunk of your profits. In addition, tooling will wear prematurely, part dimensions may vary, and even operators’ health could be affected. Let’s take a close look at these systems. Air Systems Air systems are the easiest to maintain. They usually consist of a separator (it separates condensation from the air system), a regulator, tubing, and a solenoid (that turns air on and off). In this system, the focus is on the separator: replace the element and clean the bowl; then, make certain the air is flowing out at the required pressure; and you are finished. Mist Systems A mist system is a mixture of air and liquid. It usually consists of an air separator, regulator, reservoir, solenoid, and tubing. This is another system that is easy to maintain. Change the separator element; clean the reservoir; and check the amount of liquid mixing with the air. Do this by counting drops of liquid mixing in the air during a specific time period. Some units are digitized and the flow is actually displayed. Check the outgoing mist for liquid content by putting a piece of cardboard in front of the mist line. Look for liquid to appear once the system is energized. Oil-Based Coolant Systems Oil-based systems tend to be easier to maintain. Drain the oil, clean the sump, change the filters, fill the sump with new oil, and run the pumps. Then, listen to the pumps for noise and output pressure. If the pump intake is engulfed in chips, it is likely that the pump will have some premature wear, and that chips were transferred down the line. This will affect the coolant pressure and require that the lines and solenoids be cleaned. Most sumps have baffles built into the sump that keep the chips away from the pumps. However, if the sump is not cleaned periodically, the chips will spill over the baffles. Too many chips also can make a coolant system seem like it has a leak and can even act like a siphon, drawing coolant from the sump to the floor. Water-Based Systems Have you ever come back from a long holiday weekend or company shutdown, turned on your coolant, and just about gagged from the smell? Have you noticed that your coolant is slowly changing colors? Do you get rashes or dryness on your hands and arms? Or, possibly, do your lungs feel heavy when you breathe? Is your tool life changing? These are all symptoms of bad coolant. The longer this system is ignored, the worse it is going to get. Water-based systems are a little more work and require daily checks. It is very important to change your coolant periodically. Most machines use “waylube,” which drips into the coolant and contaminates it. Paint from castings and hydraulic leaks will do the same. As you can see, your coolant can have all types of contaminants that will affect its performance. You will need to invest in a tool called a refractometer. You can find these in most industrial supply houses, and they cost around $250. Low coolant concentration will cause bad tool life, bacteria growth, rusting of machine areas, and many other problems. High concentration will cause the coolant to insulate the tooling and part, causing high heat that also will affect your part and tool life. It also can cause dermatology and respiratory problems. As far as maintaining this system, follow the same procedure as oil-based systems. If you find bacteria, the entire machine will have to be cleaned out. Since we ended this article on cleaning, that is where we will pick up next time. Talk to you next month. Mike Breen started his career as an aircraft electrician in the U.S. Army’s 101st Airborne. A Certified Electronic Engineer with 14 years experience in machine tool repair, he presently is a Field Service Engineer with Ellison Machinery Company of Wisconsin. Mike has held this position for more than six years, during which he has designed and implemented complete preventive maintenance programs for many successful companies resulting in significant increases in their machines’ performance. For comments and inquiries about these articles, his e-mail address is mbreen@ellisonwi.com - August 2000 |
The coolant system is probably the most overlooked system in machine tools today.