accordingly , the present invention provides a process of manufacturing spark erosion electrode , which comprises plating with zinc , by galvanising , a core wire made of brass , and of diameter more than the desired diameter of the final wire ; putting coil ( s ) of the zinc plated wire in a bath pot ; heating the pot in double vacuum furnace at a temperature below the melting temperature of zinc for a prolonged period of more than 24 hours , the temperature of the furnace being increased gradually from a starting temperature of 60 °- 70 ° c ., with the final temperature , depending on the required thickness of zinc to be absorbed within the brass , and the diameter of the wire , being held for 10 to 20 hours , gradually cooling the pot upto the ambient temperature over a prolonged period of about 24 hours ; drawing the wire to reduce its diameter to an intermediate stage almost upto the desired final diameter thereof ; subjecting coil ( s ) of the wire to gradual heating in double vacuum atmosphere for prolonged period , as done earlier , and carrying out final drawing of the wire upto its desired diameter , optionally , followed by resistance annealing thereof , in the manner such as herein described . preferably , the core wire is produced from a square wire , spirally cut from a disc / plate made of the starting composition of brass , by centrifugal casting , said square wire being gradually shaped to the said core wire of desired diameter , by drawing , followed by annealing and pickling , as required . in a particular embodiment , centrifugal casting is done with a composition of 61 . 5 % copper and 38 . 5 % zinc with plus minus 0 . 2 %. to get precise composition both outer portion as well as the central portion of the disc are discarded . at high speed centrifugal process , heavier particles go to the top portion of the plate and the lighter particles come at the central portion . the middle portion is more or less of uniform composition . however , the above composition of the wire is extremely difficult to draw and frequent inter annealing is required to get a diameter of around 3 . 00 mm . the prolonged heating of the coil ( s ) of wire , below the zinc melting temperature ( i . e . 419 ° c .) results into : ( i ) absorption of zinc inside the brass to a great extent forming highly enriched zinc composition brass known as kirkendal effect , and ( ii ) to get a granular structure which provides better conductivity as well as better splashability due to lower vapor pressure . in a preferred embodiment , the square wire is drawn through round dies to obtain round wire , the latter being welded together , if necessary , to get a big coil thereof followed by mechanical polishing of the same , with the help of grooved grinding wheel . as stated earlier , the outer and central portion of the disc / plate are discarded , while making the square wire from the disc / plate , by spiral cutting , with a view to get uniform composition of brass . preferably , prior to plating with zinc , the coil ( s ) of wire is ( are ) annealed and then pickled . the coil ( s ) of wire is ( are ) subjected to double vacuum atmosphere by creating vacuum in the bath pot and also in the furnace . preferably , the vacuum is created in the bath pot and in the furnace by usual sucking followed by introduction of nitrogen , and pumping out the same , and repeating the said procedure , if necessary , with a view to make the inside of the bath pot and that of the furnace totally free from oxygen . the coil ( s ) of wire , duly cooled inside the pot by gradual cooling of the latter for a prolonged period , is ( are ) pickled e . g . by sulphuric acid , prior to further drawing thereof . the resistance annealing of this finally drawn wire may be done by resistance heating arrangement , provided in - built with the drawing machine , as known in the art , where high current of electromotive force is caused to be passed through the wire at low voltage so as to heat the wire almost immediately due to the resistance of the wire . in a particular embodiment , the centrifugal casting is done at 600 rpm to get a disc / plate of 600 mm outer diameter and thickness of 16 mm . preferably , the cast disc / plate surface is subjected to grinding / scalping for surface cleaning thereof . prior to spiral cutting , rolling of the plate / disc is done to reduce the thickness thereof upto 6 . 5 mm . thereafter , square wire of 6 . 5 mm × 6 . 5 mm is made from the disc / plate by spiral cutting . then , the square wire is drawn through round dies to obtain round wire of 5 . 60 mm diameter . in the next stage , the diameter of the wire is reduced to 3 . 0 mm by drawing , preceded by inline annealing and pickling , and said wire is plated with zinc by galvanising . preferably , the inline annealing of the wire is done in double vacuum furnace at 620 ° c . for a period of 5 hours . the pickling of wire may be done with sulphuric acid . preferably , 10 to 40 microns of zinc is provided on the surface of the wire by zinc plating . thereafter , the coil ( s ) of wire drawn upto 3 . 0 mm diameter and kept inside the bath pot , is ( are ) gradually heated in the furnace , both the said pot and the furnace being kept under vacuum and in total absence of oxygen , as aforesaid , the temperature of the furnace being gradually raised upto 370 ° c . to 395 ° c . and the duration of the heating at the said temperature is maintained for 24 - 26 hours . after creation of the vacuum in the pot and in the furnace , the temperature is gradually increased from 60 °- 70 ° c . in steps of 50 ° c . at an interval of 2 hours upto 300 ° c ., and then at 25 ° c . upto 350 ° c ., and at 10 ° c . upto 380 ° c ., and thereafter at 5 ° c . at the intervals of half an hour , and holding the final temperature , so raised , for a period of 18 to 20 hours . the coil ( s ) of wire , as obtained finally , is ( are ) spooled . in the process according to this invention highest possible overall zinc content can be achieved but at the same time it can be drawn to fine sizes with maximum reduction of upto 96 % area reduction without inter annealing . this gives huge process cost reduction and finally the wire is stress released at a temperature of about 37 ° c . and ultimately a tensile strength of more than 95 kgs / cm can be achieved . this tensile strength will be most ideal for modern auto feed machines and also for high tension cutting to set most accurate vertical cut . it would be appreciated that in the hither - to - known process / systems the wire stays inside the pipe type furnace around 8 to 10 seconds . this is equivalent to treatment of about 40 mm wire per minute . for a standard size of 0 . 25 mm wire at a speed of 40 mm per minute , a production of 24 kg / 24 hours may be expected . for a standard furnace of 31 pipe at 75 % efficiency approximately 540 kgs of production is expected against the production of 1000 kgs per 24 hours according to the process of this invention . so , the production rate is about double in the type of production according to this invention . again , in the case of pipe type furnace production , the cost is higher because of continuous supply of reducing atmosphere i . e . combination of nitrogen and hydrogen , whereas in the process of this invention , this is not required . the invention will be illustrated hereinafter with reference to the following example : a disc was made , by centrifugal casting , from molten brass having composition of 61 . 5 . copper and 38 . 5 % zinc ± 0 . 2 %. the centrifugal casting was done at a speed of 600 rpm with cast disc of outer diameter 600 mm and thickness of 16 mm . the disc was properly scalped and rolled to reduce the thickness thereof upto 6 . 5 mm , and to increase the diameter of the same . spiral cutting of the disc was done to get rod coil , and a square wire of 6 . 5 mm × 6 . 5 mm was cut . prior to spiral cutting , the outer and the central portions of the disc were discarded to get uniform composition , remaining at the middle portion thereof . the square wire was then passed through round die and ultimately at 5 . 60 mm diameter round shaped wires in coil form , of 100 kgs weight each were obtained . then these coils were annealed in double vacuum furnace at 620 ° c . for a period of 5 hours , and then pickled with sulphuric acid . the wires were welded to make the coils . thereafter the wires , in coil form , were drawn to 3 . 00 m dia , followed by annealing and pickling thereof . the wires , so treated , were then plated with zinc by age - old galvanic process and then put under the furnace of double vacuum . for such purpose , the coils of brass wire , coated with zinc were kept inside a bath pot , and the pot was inserted in a furnace . the bath pot as well as the furnace were processed to create double vacuum . the vacuum was created in the bath pot and in the furnace by usual sucking followed by introduction of nitrogen , and pumping out the same , and repeating the said procedure , if necessary , with a view to make the inside of the bath pot and that of the furnace totally free from oxygen . after the vacuum was created the temperature was gradually increased in steps of 50 ° c . at an interval of two hours upto 300 ° c . then 25 ° c . upto 35 ° c ., and 10 ° c . upto 380 ° c . and thereafter 5 ° c . at the interval of half an hour . the time of holding the final temperature was 18 to 20 hours , and the total time of keeping the coils inside the furnace was between 24 to 26 hours . the pot was then taken to cooling vat and cooled very gradually upto room temperature for about 24 hours . then the coils of wire were taken out from the annealing pot and were subjected to both inline mechanical polishing of the wire surface by means of grooved grinder wheel as well as for chemical surface cleaning as preparatory steps for the lubricant carrier facility of the wire to help maximum possible drawing of the coils of wire in a single shape at a reduction of more than 94 . 3 % in area to get the diameter of the wire upto an intermediate shape between 1 to 1 . 25 mm . then the wires were again charged inside the double vacuum furnace and same procedure of prolonged heating was done . with this second prolonged heating of the wires , top layer zinc further penetrated towards the core and there was a gradually higher zinc content towards the surface of the wire . the purpose of the gradual change of zinc content was to provide better splashibility of the edm wire so that it would perform far better than the conventional edm wire . thereafter , final drawing of the wire upto 0 . 15 to 0 . 30 mm was done in a wet type drawing machine and in the same mechanical composition these were put to resistance annealing . this was done by resistance heating arrangement , provided in - built with the drawing machine , as known in the art , where high current of electromotive force was caused to be passed through the wire at low voltage so as to heat the wire almost immediately due to the resistance of the wire . the said resistance annealing was done to release the in built stress and to get the desired straightness of the finished wire , and the wire was heated when the wire was in tension . finally the wire was spooled and said spools were put in a chamber , wherein water was sprayed to form steam with a view to protect the wire surface . it is to be understood that various modifications of the process according to this invention are possible within the scope of what has been described hereinbefore and will be claimed hereinafter . various changes which occur in the composition and metallurgical structures of the electrode wire , during its production , following the process according to this invention , are illustrated by way of photomicrographs of the sections of the wire , at different stages , as shown in the accompanying drawings , wherein , fig1 : shows , in section , one embodiment of a core wire made of brass ( indicated by 1 ) in annealed condition , but prior to plating with zinc by galvanizing . fig2 : shows , in section , the same core wire , as shown in fig1 which has been plated with zinc , where the α - brass core is indicated by 1 , and the zinc - coating therearound is indicated by 2 . fig3 : shows , in section , the same wire , as shown in fig2 which has been heated in vacuum at temperature below the melting temperature of zinc for 24 to 26 hours , with the result , due to kirkendal effect , that the core remains α - brass , as indicated by 1 , while the zinc coating ( indicated by 2 in fig2 )-- transforms to β - and α - brass , ( as indicated by 3 . fig4 : shows , in section , the finally drawn wire from the treated wire , shown in fig3 after reduction in cross sectional area of about 95 %, where the core remains α - brass , as indicated by 1 , and the surrounding layer is β - and γ - brass , as indicated by 3 . fig5 : shows , in , section the same embodiment of the finally drawn wire , as shown in fig4 which has been stress - released after final resistance annealing , as described hereinbefore . as seen , the composition and structure of the core 1 and the outer layer 3 remains unchanged .