Abstract: Based on the machining principle analysis of the nature ruled surfaces‚the technologies of NC program-ming for intricate nature ruled surfaces by wire-EDM were studied‚including the profile marking standard‚the algo-rithm of seeking corresponding points‚equa- l error synchro-linear approximation of profiles and the method to calculate the maximum inclining angle of ruling．It is found that less approximated curves and shorter NC codes can be obtained when the equa- l error synchro-linear approximation is employed to approximate the profile curves‚and that the maxi -mum inclining angle of ruling can be efficiently obtained via the proposed calculation method during programming pro-cess．All the technologies mentioned above are verified and applied in the proposed NC programming system for low-speed wire-EDM．

Key words: wire-EDM, intricate ruled surface, equa- l error linear approximation, NC programming, maximum in-clining angle, inclining angle verification