Method for Making Metal Wire for Wire Electrical Discharge Machining and the Metal Wire Product Thereof

Abstract

A method for making a metal wire adapted for wire electrical discharge machining, comprises the steps of: A. Preparing a brass core wire having a diameter of at least 1.2 mm and having a zinc content of less than 40% by weight; B. Plating at least a coating material of zinc alloy having a zinc content of more than 75% by weight on the brass core wire to form a coating layer on the core wire so as to form a coarse wire by a spray plating process by atomizing and depositing a plurality of zinc alloy particles of the coating material on at least a surface portion of the brass core wire to form a plurality of cleavages or cavities on or in an outer surface of the coating layer of the coarse wire; and C. Drawing or stretching the coarse wire to obtain a metal wire product having a diameter ranging from 0.15 mm through 0.35 mm.

I claim: 
     
         1 . A method for making a metal wire adapted for wire electrical discharge machining, comprising the steps of:
 A. Preparing a brass core wire having a diameter of at least 1.2 mm and having a zinc content of less than 40% by weight;   B. Plating at least a coating material of zinc alloy having a zinc content of more than 75% by weight on the brass core wire to form a coating layer on the core wire so as to form a coarse wire by a spray plating process by atomizing and depositing a plurality of zinc alloy particles of the coating material on at least a surface portion of the brass core wire to form a plurality of cleavages or cavities on or in an outer surface of the coating layer about the core wire; and   C. Drawing or stretching the coarse wire to obtain a metal wire product having a diameter ranging from 0.15 mm through 0.35 mm.   
     
     
         2 . A method according to  claim 1 , wherein said spray plating process comprises plating a coating layer comprised of at least two zinc alloys having different zinc contents in the coating layer on the brass core wire, whereby upon atomizing or depositing the coating layer on the brass core wire, different zinc alloy particles will be presented on the outer surface of the coating layer of the coarse wire. 
     
     
         3 . A method according to  claim 1 , wherein said the brass core wire is preheated to 350° C.˜420° C. before being spray plated. 
     
     
         4 . A method according to  claim 1 , wherein said coarse wire is stretched to have a diameter of 0.8 mm in a temperature range of 100˜150° C., then stretched, at normal temperature or in a temperature range of 200˜300° C., to have a diameter of 0.15˜0.35 mm, and further annealed in a temperature range of 250° C.˜350° C. for 1˜5 hours to obtain the metal wire product. 
     
     
         5 . A method according to  claim 4 , wherein said metal wire, when being annealed, is moved to approach a magnetic field of an induction coil. 
     
     
         6 . A method according to  claim 1 , wherein said brass core wire is guided by a plurality of rollers to be spray plated within a spray plating zone for one time or plural times of the spray plating process. 
     
     
         7 . A method according to  claim 1 , wherein said coating layer on said core wire has a thickness of 10 μm˜100 μm. 
     
     
         8 . A metal wire adapted for wire electrical discharge machining comprising:
 a brass core wire having a zinc content less than 40% by weight; and   a coating layer coated, by a spray plating process, on said core wire to form a coarse wire, said coating layer having a zinc content more than 75% by weight and including a plurality of zinc alloy particles stacked and deposited on said core wire;   said coating layer having cleavages or cavities formed on an outer surface of the coating layer upon stretching or drawing of said coarse wire.   
     
     
         9 . A metal wire according to  claim 8 , wherein said coating layer further comprises an outer crystal layer of pyroelectricity upon approating an induction coil. 
     
     
         10 . A metal wire according to  claim 8 , wherein said coating layer comprises a zinc alloy containing at least two different zinc contents therein, whereby upon atomizing during the spray plating process, a plurality of zinc alloy particles of at least two different zinc contents will be stacked and deposited on the core wire.