Coolant Skimmer Triples Coolant Life

Removing Oil Cuts Machine Downtime, Extends Tap Life

Any problem in the Ingersoll Master center in the Bobst Group’s Roseland, NJ, machine shop affects the productivity of the entire plant. The center, which has a 50 hp spindle and handles workpieces up to 3 m x 2 m x 1m, machines a variety of components for the Bobst Group’s line of paper packaging equipment.

According to Kit Payne, maintenance section manager, the machining center is a real workhorse. It runs two shifts a day, often operating for more than 20 hours at a time. Machining large plates and castings that require a lot of chip removal are all in a day’s work. The machine can take a 1/2″ deep x 8″ wide cut at a rate of 40 inches per minute. In one operation, a six-ton casting is reduced to just five tons.

The Problem

Just as the parts it machines are huge, so too are the center’s coolant requirements. According to Payne, the center relies on an 800-gallon coolant sump. The steel tank, located within the machine’s foundation beneath the shop floor, measures about 5 feet square and 5 feet deep. When it was installed in 1994, the initial charge of coolant lasted several months, but soon after, a charge would last no more than eight weeks.

“After we replaced the first charge, there was a drastic change,” Payne said. “The coolant really started to deteriorate quickly.” In addition to acquiring a rancid odor, it often became gummy. The machine also began snapping taps at a very high rate. “We wouldn’t get three holes out of them and they would break,” Payne said. The taps were especially vulnerable because the tapping operation requires the coolant to lubricate the tool in addition to dissipating heat.

Why Coolant Goes Bad

The cause of the deterioration was a thin layer of oil which formed on top of the coolant while it was in the sump. Sources of the oil included way lube, minute leaks in the hydraulic system, and the natural deterioration of the coolant itself, in which the vegetable and mineral oils that make up the coolant separated from the water. This oil prevented oxygen from mixing with the coolant, allowing anaerobic bacteria to thrive and causing the coolant to break down even more. Losing the machine for even a day was a big blow. “If you’re doing that every two months, that’s a lot of production time that goes down the tubes,” Payne said.

Another Solution

Bobst then tried using a shop vac to suction the layer of oil off the coolant. “We noticed that the coolant was improving a little bit,” Payne said. “But our oil consumption problem wasn’t going away. We were still using a lot of coolant because you wind up taking out a lot of coolant along with the oil. It’s self-defeating.”

Coolant Skimmer Solution and Measurable Results

At this point, Payne decided to install a Tote-It Portable Oil Skimmer and an Oil Concentrator from Abanaki Corporation. The skimmer’s 4” belt operates on a motor and pulley system attached to a stabilizer bar immersed in the coolant.

The Tote-It makes use of the differences in specific gravity and surface tension between the coolant and the oil, which allows the belt to attract oil from the surface of the coolant. After traveling over the head pulley, the belt passes through tandem wiper blades that scrape oil off both sides of the belt. The oil is then discharged through a 1-1/4″ ID hose into the concentrator.

The concentrator utilizes gravity to separate the oil from the small amount of coolant picked up during the skimming process. It ensures virtually complete oil/water separation so that the coolant can be returned to the system.

Since installing the skimmer, Payne reports that a coolant charge now lasts at least six months. As a result, coolant replacement costs and machine downtime have been reduced, as has the cost of replacing taps. Based on the skimmer’s performance, Payne recently installed two Abanaki Mighty-Mini Portable Oil Skimmers on the shop’s horizontal boring machine and vertical machining center.

Abanaki Corporation