A Study of the Effect of n-Butyl Acetate on a Motor and Gear Reducer System For A Deep Ice Coring Drill

During the summer of 1989, PICO tested a prototype of a new deep ice core drilling system. The drilling system was designed for using diesel oil as drilling fluid. In the summer of 1990, the fluid was replaced with n-Butyl Acetate. Since n-Butyl Acetate is an extremely bad lubricant, the wear-rate on mechanical components was expected to be high.

The purpose of this study was to determine the wear on the motor and gear reducer in the drilling system and to evaluate potential situations for mechanical failures due to wear.

The motor and gear reducer were operated in an n-Butyl Acetate bath with a temperature between 0 degrees and -10 degrees Celsius. Two failures occurred during the test, the first failure after 79 working hours and the second after 94 hours. Both failures were due to the same ball bearing breaking down. The lack of lubrication caused major problems. The endurance of the ball bearings was shortened noticeably. The wear-rate on other components in the gear reducer was high.

The lubrication mode in the motor and gear reducer could be improved by preventing the n-Butyl Acetate from surrounding the components. The motor and gear reducer could be placed inside a sealed container. The passage in the container for the output shaft could be sealed with Teflon seals, since n-Butyl Acetate does not dissolve Teflon.