July 2008 Edition

LUBRICANTS

Little Lubricant, Big Clean

By adopting a near-dry coolant process for its band saw, a job shop improved production and job safety

Even though they began as a robotic welding shop, production sawing has become an important revenue center for Bear Metal Works, Buffalo, NY, which adds value to steel by providing secondary operations. While some businesses in the area have been closing their doors due to a slowing automotive industry and high taxation, Bear Metal Works owner Barrett Price, in his 10th year of business, has purchased a building, an acre of property, added equipment, and added employees. Now a seven-person operation, he anticipates adding at least two more employees. Price said he still believes in steel and sees opportunity to grow and niches to fill.

Manual Cleaning Required

One of the key service centers in the company is an 81APC Vertical Band Saw from Marvel Mfg. Co., Oshkosh, WI. The increase in sawing activity was a business driver for the expansion, requiring additional space to manipulate larger volumes of customer materials. The automatic saw is used for heavy duty cuts on steels ranging from mild carbon to stainless. The standard lube system on the 81APC is a flood system which pours coolant onto the blade and cutting area at a continuous rate.

Among the highest volume jobs on the automatic saw are finish cuts made to 3"×3" square tubing. The tubing is stacked, loaded on the saw in bundles, and cut to ensure uniform dimensions and readiness to ship to the customer. A five-ton overhead crane reduces labor for moving and stacking larger bundles and longer lengths. While the cutting process is productive, it is hard on saw blades, since the blade passes in and out of the material on its way through the bundle. Good lubrication was always a factor to make the best use of blades.

On the 3"×3" job, a major issue surfaced, also tied to the lubrication process. The flood lubricant was getting inside the tubes and between the stacks, causing rust and sometimes debris on the finished material. The company and its customer shared concerns regarding excess flood coolant on the finished surfaces, but they had little recourse since flood cooling is the standard in the band sawing world.

Instead, Bear Metal dealt with the problem in the way many companies might – by tapping its profits with the additional labor. Before shipping to the customer, the material had to be destacked for cleaning to remove the rust from all surfaces. Sometimes, the parts had to be sent for sandblasting before they could be used. When a local industrial solution provider visited the Bear Metal facility, he suggested near-dry sawing might be a good way to eliminate the excess lubricants and the rust problem. The company was open to the idea; Price had heard of this process but never considered it for his own operations.

Wet Saw Blade – Dry Parts

Near-dry sawing is a concept that focuses on saw blade lubrication using very small amounts of lubricant. By using greater precision to apply higher lubricity oils, friction is reduced and heat is removed, eliminating the need for a constant coolant flow. Integration of near-dry sawing means the purchase and retrofit of a small aftermarket lubrication system, or the selection of an optional OEM system on a new saw. The systems consist of one or more small positive displacement injector pumps which dispense lubricant as the blade turns and advances into the cut. The lube is applied through a variety of nozzle types, directed to the tooth face and sides of the blade.

Bear Metal Works purchased a 200-3S Saw Coolubing System from Unist, Inc., Grand Rapids, MI, a manufacturer of lubrication systems designed to reduce lubricant consumption by focusing on precise application methods. The company promotes the concept of near-dry, not only in band and circular sawing, but in other operations such as machining and forming.

The lube system manufacturer also recommended changing the lubricant to vegetable-based oil, because it offered higher lubricity than petroleum- or water-based products. The same lubrication, or better, can be accomplished even though much less material is applied.

"Because of polar properties in the vegetable-based oil, it stays on the surface longer, before it is consumed; requiring less lubricant." Larry Tilma, Unist general manager, said. Coolube 2210EP, a vegetable lubricant with a high-pressure additive for ferrous metal, was selected for the automatic sawing project.

“We know we are buying fewer blades and they are lasting longer”

Bear Metal applied the lube using a single spray nozzle directed to the cutting face of the blade. Price and his operators put the Marvel through its paces using the new lubrication process. During the cuts on the 3"×3" tube stock, the blade conditions were observed, and temperature measured with a laser thermometer. The cutting edge of the blade was an acceptable 70°F. The back half of the blade however was about 130° – almost twice the temperature. This extra heat caused the saw’s guide arm to heat as the blade passed, and the cuts were off square. The back side of the blade experienced friction as it passed through the bundles, either because of slight binding, or chips still lodged in the cut.

A modification was made in the lube system, by adding an additional line, plumbed into the blade guide on the 81APC. The additional line let the lube coat the entire surface of the blade, reducing friction on the back in the same way as on the front of the blade. This counterbalanced the temperature on the blade and let the cuts continue at the previous rate.

Cleanliness Cuts Costs

The lubrication process gave Bear Metal increased blade life.

"It’s hard to assign numbers to the improvement because we’re a job shop and we use the saw differently every week," Price said. "But, we know we are buying fewer blades and they’re lasting longer."

The major result was the elimination of parts handling and cleaning. The company no longer has to separate and restack the finished bundles. There are no more rust problems, and the finished cuts show better quality with the lubrication change. Bear Metal can reassign the labor and the time once spent on clean-up to other revenue producing operations. The finished bundles are shipment-ready when they are off-loaded from the saw.

While the shop achieved productivity changes with the new lubrication process, what made this project a success were some of the less-anticipated results. The operator no longer deals with excess coolant spilling off the material as the saw is loaded and unloaded. This keeps him cleaner as he takes the material on and off the crane, and also helps with the cleanliness of the entire work area. The cleaner environment also improves shop safety.

"Our people are safer in the work area because there’s no excess coolant on the floor and around the machine," Price said.

He also said how most of the variables related to flood cooling were eliminated. One operation, cutting 4" square solid steel billets stacked two high and two wide, produced an enormous amount of chips. With the previous lubrication method, the chips were wet and messy, and relied on the coolant flow to remove them. Now the chips are dry, fall off, and are easy to clean up.

Since the coolant is no longer flowing in the system there are no issues such as coolant rancidity, operator dermatitis, sumps to clean, and fluid disposal. The company uses only about a gallon per month of the vegetable-based Coolube 2210EP, which is consumed in the process and does not spoil. Price said he plans to outfit his other two sawing stations with the Unist systems. Unist, Inc.

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