Method of making a hole in a thick-walled metal material

Claim 1

A process of making a hole in a metal material by forming an arc and by projection of pressurized fluid, the method comprising the steps of: bringing the tip of an arc electrode wire into contact with said metal material while receiprocating said arc electrode wire in a direction lateral to a length of said electrode wire; applying between said metal material and said electrode wire an electrical potential sufficient to form an arc therebetween, whereby said electrode wire is consumed and a hole is formed in said metal material; projecting a pressurized fluid towards the hole along one side of the exterior of said arc electrode wire; and laterally reciprocating the arc electrode wire to thereby form an entry path and an exit path for said pressurized fluid within the hole, whereby the pressurized fluid is introduced into the hole through said entry path, passes to the bottom of the hole to entrain molten metal lumps and exits to the outside together with said lumps through said exit path.