From the time people first began to machine metals they have used some form of coolant to reduce cutting temperature and reduce tool wear. Animal fats, kerosene and even plain water were used in the earliest times. Then, as spindle speeds increased and CNC machines emerged in the 1940s and 1950s, metalworking required more sophisticated coolants.
Today, virtually all CNC machines are or can be equipped with coolant delivery systems. The conventional approach is to spray the coolant – either at moderate or high pressure – directly onto the workpiece where the cutting takes place. For a number of applications, however, this method falls short.
This was true for Burr Oak Tool in Sturgis, MI. The company was founded as a general machine shop in 1944 but when in 1952 a customer asked them to design and build a special machine to make condenser coils for air conditioning units, the company found a new direction. Today, with 300+ employees and 420,000 ft2 in 3 production facilities, Burr Oak Tool supplies special machines and tooling to virtually every user of air conditioner evaporator condenser coils in over 70 countries around the world.
Over the years the company sought to continuously refine their processes to reduce cost and increase productivity. In the mid 1980s they began experimenting with through tool high pressure coolant delivery on their high speed steel drills.
“We knew that the primary benefits of applying machine coolant were to control the temperature of the workpiece to allow faster speeds and feeds, as well as getting longer life out of the cutting tools.” Explains CEO Newell Franks II.
“Using the traditional method of flooding the cutting zone wasn’t getting the job done for us. I knew that gun drills used through-hole coolant so I decided to see what it would take to adopt that method to what we were doing. To get started I reached out to our hydraulic component supplier and used some of their products to test my theory.”
Newell’s theory centered on the fact that twist drills pull material out of the hole as they work, which means that simply spraying coolant at the work area allows only small amounts of fluid to drizzle into the hole as it works against the pumping action of the drill. Forcing the coolant through the center of the tool to the cutting tool point more efficiently cools the workpiece and lubricates the drill. As a bonus, this action also flushes chips out of the hole, thus avoiding re-cutting that causes premature tool wear.
“Initially we ran pressures from 200-700 PSI as we experimented. We also used multi-stage centrifugal pumps to get pressures up to about 250 PSI. The initial results were very promising. When we started to see positive results on the drilling machines, we turned our attention to the milling machines. We modified our milling cutters so we could pump the coolant into the pocket to more uniformly cool the cutting tools, eliminate thermal shock and more effectively evacuate chips.
“When our experiments proved successful we began looking for available high-pressure delivery machines. We tried a few brands that didn’t perform to our expectations and then we purchased our first LNS ChipBLASTER in 1994. We found that these units performed significantly better, lasted longer and required less maintenance. The LNS ChipBLASTERs allow us to run 1,000 PSI coolant on all of our machines with coolant filtration levels of one micron. This combination has allowed us to turn hours into minutes and minutes into seconds when machining steel and aluminum parts. We currently have 60 LNS ChipBLASTER high pressure systems in use.”
When Burr Oak Tool first began working with LNS ChipBLASTER machines, they experimented with pressure and flow on various applications. By consulting LNS ChipBLASTER charts that listed the number of gallons of coolant that flows through various size orifices at 1,000 PSI, Burr Tool realized that some of the larger drills and milling cutters they used would require greater volumes of coolant. They then built special flow gauges that mounted on the spindle or mill tool holder to measure precisely how many gallons per minute they needed to deliver.
They determined that their CAT 40 machines required 13 GPM and the CAT 50 machines needed 21 GPM to achieve more consistent pressure and cooling, so LNS ChipBLASTER changed the pumps accordingly. By delivering the precise amount of flow and pressure, Burr Oak Tool saw improved tool life and faster throughput.
One example of the benefits of through-tool high pressure coolant at Burr Oak Tool is a stripper plate for a die that requires 3,200 holes drilled into 34 RC 4140 steel The holes are 1mm in diameter and 6mm deep. These are starter holes through which EDM wire is threaded. Originally, this process involved a solid drill – and typically produced a number of broken drills – and lots of pecking. Using the LNS ChipBLASTER to deliver high pressure coolant through a single drill enables the machine to create all 3,200 holes with no pecking. This coolant method combined with using a speed head cuts production time from 6 – 8 hours down to 40 minutes.
Because applications like this one require drilling very small holes, The LNS ChipBLASTER units are equipped with 1 micron filters that eliminate tiny particles that could clog the small tools.
“When people ask me about how through-tool high pressure coolant delivery helps our production, I tell them it’s as simple as this: With the right equipment, like the LNS ChipBLASTER systems, we can cut steel like it’s aluminum and aluminum like it’s wood.”