Many see the fluids as an unnecessary evil to the grinding process, failing to realize that selecting the right grinding fluid can lead to significant improvements in cycle time, surface quality, finishes, secondary operations, such as tool coatings. Oelheld has put together a short article on grinding oil considerations.
The oil-off (also known as loss-of-lubrication or oil-out) performance evaluation of gears is of significant interest to the Department of Defense and various rotorcraft manufacturers, so that the aircraft can safely land in an accidental loss-of-lubricant situation. However, unlike typical gear failure modes such as pitting or bending fatigue where early detection is possible, gear failure in an oil-off situation is very rapid and likely catastrophic. Failures rapidly result in the loss of torque transmission and the inability to control the aircraft.
Base oils play an important role in determining the performance of an industrial gear oil. They influence characteristics such as low temperature performance,
biodegradability, energy efficiency and high temperature thermal and oxidative stability.
Oil-out conditions, or conditions
in which an aircraft is
operating without any oil in its
gearbox or transmission, are
devastating for an aircraft's
hardware. Even the sturdiest gears
usually can't last 30 minutes under such
conditions before they catastrophically
fail, and the whole system usually follows shortly after. That doesn't leave pilots with a whole lot of time to find a suitable location to land in the case of an oil-out emergency.