How one manufacturer was stopped in their tracks by not choosing the right coolant for their new automated high-pressure machining center.
High-pressure coolant systems can provide important benefits, especially when working with difficult metals like superalloys, titanium and stainless steel. High-pressure coolant, typically operating at 1,000 psi or higher, works by applying the fluid directly to the point of cut with enough force to prevent vapor formation. The benefits include superior lubrication and cooling, less tool wear, higher cutting speeds and better chip control, resulting in less downtime and increased productivity.
Over the last ten years, even with the recession, the market for high-pressure coolant has grown at an impressive rate. It has become standard in many manufacturing sectors.
Unfortunately, high-pressure systems can also have an unpleasant side effect – foaming.
Greg Antoun, President of ChipBLASTER, a leading manufacturer of high-pressure coolant delivery systems, explained, “When coolant foams it entrains air bubbles and the density of the coolant drops dramatically. Because the foam itself is so much lighter than water-based coolant, it can’t exert the force required to make high pressure work. Foam doesn’t cool the part or lubricate the tool effectively. For practical purposes, water-based coolant is not compressible, so when coolant foams the air bubbles are compressible and it can’t be effectively pumped at all. It’s like trying to hammer a nail with a sponge.”
“Foaming kills production, often reducing the effectiveness of hole drilling by 90 percent,” he added. “Both cycle time and tool life can increase 10X by eliminating foam.”
Foaming coolant causes increased downtime, longer cycle times, more part rejections and increased coolant usage. In addition, the slip-fall potential with foam on the factory floor is a safety hazard and adds to increased disposal costs.
“Everyone hates the ugly mess of foam bubbling out of a machine onto the shop floor,” said Antoun. “We have all seen operators that have to keep a mop next to their machines. The operator hates the mess and production suffers.”
The key to mitigating foam in high-pressure applications is selecting the right coolant in the first place, but too often coolant is the last thing manufacturers think about when buying and operating high-end machining systems.
“Coolant is a mystery to most people,” said Antoun. “They often buy only on cost with disastrous results.”
The Coolant Matters
Actually, coolant selection can make a big difference in how your equipment operates. Just ask Jim Legg, General Manager of LB Pipe & Coupling of Magnolia, Texas. LB Pipe had purchased and installed a state of the art automated cell from OKUMA, which was the centerpiece of a brand-new facility for automating the production of API couplings. The cell included a pair of OKUMA 2SP-V60 machines with ChipBLASTER CV-50 high-pressure coolant delivery systems and a high-speed robotic arm from Kuka. The ChipBLASTER systems are designed to spray the coolant at 1,000 psi at the point of cut to help with lubrication, cooling and chip removal.
At the initial machine startup, “shaving cream” like foam started billowing out of the machine and onto the floor, shutting down the high pressure pumps and creating a maintenance and safety nightmare. “We were not able to make one part,” said Legg. “Even when operating at 500 psi -- half the recommended pressure for the machine -- the foaming was so severe we had to keep a pallet of liquid absorbent on hand to capture the coolant that spilled onto the floor.”
It got worse. When running at 500 psi, there was not sufficient pressure to keep the cutting area free of metal chips. As metal chips accumulated in the chuck, the robotic arm could not safely engage and grab the finished part. They had to shut down production frequently to clean out chips manually and wait for the foam to dissipate.
LB Pipe’s multi-million dollar investment in new technology was beginning to look like a disaster.
“Total Shutdown of Production”
“Basically, the foaming coolant caused a total shutdown of production with this equipment,” said Legg. “We couldn’t use the machine unless we could get rid of the foam.”
The original coolant supplier recommended adding defoamer. When first added to the tank, it seemed to help, but within two hours the foaming was as bad as ever.
OKUMA called in experts that included ChipBlaster and several tooling manufacturers. Together, they spent many hours working around the clock with LB Pipe’s engineering team and operators to find the solution.
Antoun made several modifications to the ChipBLASTER unit, which included rerouting the coolant output and return lines, pump and tank modifications, piping alterations, tooling changes and nozzle configurations. None of these things helped.
After extensive trouble-shooting, they concluded the foam was forming at the at the point of cut. New tools were installed, but the foam persisted, and chips continued to accumulate in the chucks.
Finally, Antoun suggested they bring in an expert from QualiChem, a manufacturer of high-performance metalworking fluids based in Salem, Virginia. “We see lots of foaming, and I was very confident in recommending QualiChem because their products had never failed to solve any of the foaming issues we had encountered in the past.”
A call was made to Jerry Peck, Executive Sales Engineer for QualiChem, who drove 300 miles through the night to arrive on site the next morning. He assessed the situation and recommended XTREME CUT 250C, a premium heavy-duty semi-synthetic coolant formulated specifically to optimize tool life and surface finish in high-pressure applications.
They charged one of the ChipBLASTER CV-50s with the QualiChem coolant, and started up the production line. They were immediately able to begin increasing the pressure.
After seven hours of production at 1,000 psi, the machine running on QualiChem had no foam and no chip build-up. The other machine, running at 500 psi with the previous coolant, was overflowing with foam, and chips were still accumulating inside the chuck. The decision was made to immediately clean out the second machine and recharge with the QualiChem XTREME CUT 250C.
“The difference is dramatic. Coolant is no longer a problem with the ChipBLASTER equipment. Foaming and chip accumulation have been totally eliminated.” said Antoun.
“The report back from Jim Legg was almost unbelievable,” said Rick Kimmins of OKUMA. “The result of changing coolant made a night-and-day difference in terms of better chip control and decreased downtime. LB Pipe was able to immediately run production at the machine’s full design capacity which also improved tool life by 300 percent.”
“Shortly afterward, we invited QualiChem as a metalworking fluid manufacturer, to join the select group of experts in our Partners in Thinc program. This allows us to leverage their expertise and knowledge to solve coolant problems experienced by our customers,” Kimmins added.
“Jim Legg’s story dramatically illustrates the critical importance of coolant selection,” said Mike Forest, QualiChem Director of Metalworking. “Traditionally the coolant industry has formulated with defoamers to combat potential foam issues. Defoamers do not address the root cause of foam with coolants, Instead; defoamers adjust the surface tension and make the bubbles break faster. With high pressure coolant applications, defoamers cannot dissipate the bubbles quickly enough to prevent foam problems. According to Glenn Frank, President of QualiChem, QualiChem has developed new coolant technology to address the root cause of foam which results in coolants that do not rely on defoamers as a “band aid”. QualiChem’s new coolant technology results in a premium line of cutting and grinding fluids that can run at 1000 psi In deionized water without foam.
”This experience taught me an important lesson,” said Legg. “When purchasing coolant, most people look at the price and buy the least expensive product available. I’ve learned it’s worth the money to use a quality coolant in terms of long-term savings.”
Antoun echoed the same feeling. “There’s an education gap out in the metalworking marketplace. It’s important for companies to understand that the coolant really does matter, especially as more and more manufacturers are moving to high pressure applications.”