Home / Standards / GB/T 20330-2006 GB/T 20330-2006 Active Drill diameter for use prior to tapping screw threads 攻丝前钻孔用麻花钻直径 Standard Type GBT ICS 25.100.30 CCS J41 Status 现行 Issue Date 2006-07-20 Implementation 2007-01-01 Responsible Dept 中国机械工业联合会 Drafting Unit 中国机械工业联合会