ENTRY BOARD FOR SMALL-BORE DIAMETER DRILLING AND SMALL-BORE DIAMETER DRILLING METHOD

摘要

PROBLEM TO BE SOLVED: To provide a means for reducing breakage of a drill by continuously exhibiting satisfactory lubricating operation of a lubricating layer disposed on an entry board, improving the positional accuracy of a bore, and avoiding stains of a workpiece due to dripping of lubricating ingredients in small-bore diameter drilling.;SOLUTION: The lubricating layer 4 formed on at least one surface of an aluminum-made board 2 is composed of a mixed composition containing polyethylene glycol having a number average molecular weight equal to or higher than 100 and under 1000, polyethylene glycol having a number average molecular weight equal to or higher than 10000, saponification material of polyvinyl alcohol and trimethylol propane.;COPYRIGHT: (C)2006,JPO&NCIPI