Skimming coolant costs

Author Cutting Tool Engineering
October 01, 2010 - 11:00am


END USER: Tank Component Industries, (417) 831-5100, CHALLENGE: Remove tramp oil that's contaminating coolant. SOLUTION: Portable oil skimmer that extends coolant life and minimizes the need to clean machines. SOLUTION PROVIDER: Abanaki Corp., (800) 358-SKIM,


Tank Components Industries, Springfield, Mo., produces cylinders, heads, fittings and other parts for manufacturers of tanks and vessels. TCI machines the parts from stainless steel and nickel-based alloys in a variety of sizes; tank head diameters range from 9 " to 118 ", and workpiece material thicknesses vary from 12-gauge to ½ "-thick plate.

TCI’s machine tools include a large You Ji vertical lathe, a Mazak horizontal lathe, three Mazak turning centers and two HE&M automatic saws. Until recently, all the shop’s machines shared the same problem: accumulated tramp oil from the machine ways caused coolant to smell like rotten eggs. 

According to Bryan Perry, maintenance supervisor, the tramp oil floated on the surface of the coolant and formed an air barrier “like moss on a pond.” That enabled anaerobic bacteria to multiply in the coolant, often causing it to spoil within a week. 

Perry minimized the smell by regularly draining the coolant from the machines and cycling cleaner through them. “To clean a small machine takes about 5 hours,” he said. “We have one machine that holds 130 gallons of coolant. That machine takes 2 days to clean. I have to stand there with a hose while the cleaner cycles to keep the sludge from collecting at the bottom.” Cleaning all the shop’s machines, he estimated, consumed more than 40 hours. Added to the time and labor cost of cleaning was the expense of replacing the coolant. 


Courtesy of Bryan Perry/TCI

TCI fabricated a custom universal mounting stand for the company’s Abanaki oil skimmer to facilitate moving it among the different kinds of machine tools in the shop. 

To solve the problem, TCI purchased a Mighty Mini SST oil skimmer from Abanaki Corp., Chagrin Falls, Ohio. The compact, belt-style oil skimmer works in coolant sumps and other tight locations. Oil sticks to its rotating belt, and wipers scrape the oil into a collection container. TCI chose the Model SMMS-1-12 Mighty Mini, which has a 1 "-wide × 12 "-long belt. 

The skimmer belt is made of Abanaki’s standard polymer material, which is textured to retain a small amount of oil and thereby draw more oil on subsequent passes. Abanaki President Tom Hobson said the tramp oils in machine tool coolant reservoirs usually are “gray oils. They are slightly emulsified, but they’ve also got some of the cutting dust in them.” A drop of gray oil will generally have slightly more oil than coolant. “It will float, but on the outside it is still water. Typical oil skimmers won’t pick that up. We make a belt that will get that gray oil,” he said.

According to Perry, the skimmer’s effectiveness at TCI is obvious. “I can see the oil skimmer working, oil clinging to the belt and getting scraped off,” he said. “On one lathe, I collect three-quarters of a gallon to a full gallon of oil every week.” 

The coolant color itself is an indicator. “My coolant is light blue, but it turns black in a week if I don’t skim. If I put the oil skimmer on that machine, in 2 days the coolant will be blue again,” he said.

To facilitate use of the 7-lb. skimmer on the shop’s different machines, Perry fabricated a custom mounting stand. It fits all the machines without adjustment. “I tried to make it as universal as possible. I measured all the machines and cut the pipe to fit what I needed, so I just had to have one size,” he said.

Perry said the skimmer’s integrated, 24-hour timer enables it to run through the night. The shop operates two shifts daily. “I rotate the skimmer from machine to machine about every 2 days,” he said. “I’ll let it run during the day, and at night, when nobody is here, 15 minutes on and 15 minutes off.” The skimmer can do its work while the machines are making parts because it removes oil from the coolant reservoir and therefore doesn’t interfere with production. 

Perry estimates that skimming once a week makes the coolant last 50 to 100 percent longer. And, in addition to spending less money on coolant and cleaner, TCI is saving a lot on labor, he said. “I won’t have to clean the machines for a while. I figure that the oil skimmer paid for itself within 6 months.”

Related Glossary Terms

  • alloys


    Substances having metallic properties and being composed of two or more chemical elements of which at least one is a metal.

  • centers


    Cone-shaped pins that support a workpiece by one or two ends during machining. The centers fit into holes drilled in the workpiece ends. Centers that turn with the workpiece are called “live” centers; those that do not are called “dead” centers.

  • coolant


    Fluid that reduces temperature buildup at the tool/workpiece interface during machining. Normally takes the form of a liquid such as soluble or chemical mixtures (semisynthetic, synthetic) but can be pressurized air or other gas. Because of water’s ability to absorb great quantities of heat, it is widely used as a coolant and vehicle for various cutting compounds, with the water-to-compound ratio varying with the machining task. See cutting fluid; semisynthetic cutting fluid; soluble-oil cutting fluid; synthetic cutting fluid.

  • lathe


    Turning machine capable of sawing, milling, grinding, gear-cutting, drilling, reaming, boring, threading, facing, chamfering, grooving, knurling, spinning, parting, necking, taper-cutting, and cam- and eccentric-cutting, as well as step- and straight-turning. Comes in a variety of forms, ranging from manual to semiautomatic to fully automatic, with major types being engine lathes, turning and contouring lathes, turret lathes and numerical-control lathes. The engine lathe consists of a headstock and spindle, tailstock, bed, carriage (complete with apron) and cross slides. Features include gear- (speed) and feed-selector levers, toolpost, compound rest, lead screw and reversing lead screw, threading dial and rapid-traverse lever. Special lathe types include through-the-spindle, camshaft and crankshaft, brake drum and rotor, spinning and gun-barrel machines. Toolroom and bench lathes are used for precision work; the former for tool-and-die work and similar tasks, the latter for small workpieces (instruments, watches), normally without a power feed. Models are typically designated according to their “swing,” or the largest-diameter workpiece that can be rotated; bed length, or the distance between centers; and horsepower generated. See turning machine.

  • tramp oil

    tramp oil

    Oil that is present in a metalworking fluid mix that is not from the product concentrate. The usual sources are machine tool lubrication system leaks.

  • turning


    Workpiece is held in a chuck, mounted on a face plate or secured between centers and rotated while a cutting tool, normally a single-point tool, is fed into it along its periphery or across its end or face. Takes the form of straight turning (cutting along the periphery of the workpiece); taper turning (creating a taper); step turning (turning different-size diameters on the same work); chamfering (beveling an edge or shoulder); facing (cutting on an end); turning threads (usually external but can be internal); roughing (high-volume metal removal); and finishing (final light cuts). Performed on lathes, turning centers, chucking machines, automatic screw machines and similar machines.