Time for an oil change

END USER: Dura-Mill Inc., (800) 444-6455, www.duramill.com.
CHALLENGE: Eliminate component degradation on tool grinding machines.
SOLUTION: Switching to a low-viscosity, cobalt-inhibited, hydrocracked synthetic grinding oil.
SOLUTION PROVIDER: Blaser Swisslube Inc., (845) 294-3200, www.blaser.com.

Grinding oil is essential when grinding high-performance carbide cutting tools. It’s needed to keep grinding burn at bay and provide lubricity at the wheel/workpiece interface to impart the required surface finishes. However, an oil with an improper formulation can have unintended consequences.

Dura-Mill Inc., Malta, N.Y., produces solid-carbide endmills, such as its WhisperKut and WhisperKut Plus with an asymmetrical variable-helix design to reduce harmful harmonic resonance. The toolmaker was experiencing machine tool issues but having trouble pinpointing the exact cause, noted Charles Ward, Dura-Mill’s plant engineer.

“The electrical cabling was failing at an astounding rate in several different brands of machines,” Ward said, adding that the plastic wire ways that prevent wires from becoming tangled were also cracking and falling apart.

After switching to Blaser Swisslube’s Blasogrind HC5 synthetic grinding oil, Dura-Mill eliminated degradation to plastic components in its grinding machines (above) for producing solid-carbide endmills (below).

He explained that once the outer jacket of a wire hardened and broke, the same thing would happen to the inner jacket. “In a lot of cases, when the inner jacket breaks, it’ll take the copper wire with it and the machine will fail,” Ward said. “On average, every couple of years we had to replace several thousand dollars worth of cables and be down a couple of days doing it.”

In addition, oil mist caused external plastic components to deteriorate.

On-site for an unrelated reason, an engineer from a grinding machine builder noticed the deterioration inside a machine, felt the nonsynthetic, hydro-treated grinding oil and asked about the type of oil being applied, Ward noted.

After the engineer informed the toolmaker that he had seen similar problems with that type of oil, Dura-Mill knew it needed to make a change. “We asked for a recommendation,” Ward said, “and that’s when we were directed to the people at Blaser Swisslube.”

Metalworking fluids manufacturer Blaser Swisslube Inc., Goshen, N.Y., sent Joe Giza, area manager, and Uli Kuster, grinding applications manager, to investigate the problems Dura-Mill was experiencing and present a solution. After investigating and analyzing the issues, they determined Blaser’s Blasogrind HC5 was needed and commenced testing. The low-viscosity, cobalt-inhibited, hydrocracked synthetic grinding oil is approved for use in all major oil filtration systems and is recommended by various tool grinding machine builders, according to the company.

During testing, Dura-Mill’s engineers, in conjunction with Blaser’s grinding applications team, set out to determine if any additional productivity benefits could be realized by increasing wheel speeds and feed rates on the grinders.

The toolmaker initially reduced cycle time from a previous best of 10.5 minutes to 9.25 minutes and achieved fluting rates for a ¾ " tool of 7 to 9 ipm with a 0.170 " DOC, according to Ward. “This is a substantial productivity gain, especially when you take into account that our surface finish has not decreased and no stress cracks are being introduced into the tool surface,” he said. “It is also incredible that the power draw on the machines’ spindles has not increased. We can only attribute this to the higher lubricity properties of the oil.”

Dura-Mill then sought to tweak the process to a higher level of productivity without negatively impacting tool quality. “We were amazed that we were able to achieve a 20 to 30 percent increase in our metal-removal rates pretty much across the board, with a 20 percent decrease in cycle time, on average, just by switching out the oil,” said Chris Clairmont, chief CNC programmer for Dura-Mill. He added that the Blaser oil feels slicker and cleaner than the previous product.

According to Brett Reynolds, senior applications engineer – west for Blaser Swisslube, the Blasogrind HC grinding oil series has a unique EP additive package that, when combined with the base oil, solved and stopped the attack of the sealing materials and plastic components. “It is my belief that the competitor’s oil had an additive in it that was causing the attack of the plastic and sealing materials,” he said. “As to which additive, I don’t know.”

In addition to eliminating the machine damage, which included the cables, the new oil squashed a biofilm issue that the previous oil was causing in one machine. Although biological growth is uncommon in pure oil, it’s not unheard of, Ward pointed out. “It looked like something from a frog pond floating around in there,” he said, “and it had a distinct, nasty odor. It’s been quite some time now and the problem has not returned.”