Letter 15043 Annealing of copper wire [Bangladesh] ++ Dear Sir, We are manufacturing copper uninsulated wire used for electric cable and also super enamel insulated wire. The size of the wire varies from SWG 1 to 32. We are facing a problem of having the wire oxidized/blackened soon after bringing it out from annealing Chamber. The annealing Chamber is of vacuum type having Induction coil to heat the copper wire. The Vacuum that can be applied to the Chamber is 500mmHg while the temperature approx.800+ centigrade. Please note the Chamber does not have any temp.meter. This is the process we are following to anneal the Copper wire. So, may I request to let me know how we can get rid of the problem of getting the wire oxidized/blackened in course of annealing. Hope to hear soon. Thanking you, M.SADEK - Dhaka, Bangladesh. ++ Try letting the copper cool in an inert atmosphere before exposing it to air. Trevor Crichton R&D practical scientist - UK ++ Alternatively let it cool in the vacuum environment used for the annealing. Bill Reynolds    metallurgical services Melbourne, Victoria, Australia +++++ We are facing the same exact problem and I thought it has something to do with annealing current / voltage ...we uses stainless steel cylinders for annealing. (not nickel coated as usual ..) any idea ? Amir Sharon - Israel June 14, 2006 You have not mentioned the quantity of your batch for annealing and also the kilowatt rating of induction heating. You have to also mention the cycle time of heating, soaking and quenching. What is the sealing mechanism used during annealing to prevent outside air entering. Without temperature indicator, how did you measure the temperature of your batch during annealing continuously? Balasubramanian Venkatraman - Navi-Mumbai, Maharashtra, India November 28, 2007 WE ARE MANUFACTURING COPPER TUBE, TO BE USED FOR ELECTRICAL TERMINATIONS WE CONTINOUSLY CAST THE TUBE , THEN DRAW THEM DOWN ON LONG HYDRUALIC BENCHES, AFTER SEVERAL DRAWS, THE TUBES BECOME TO HARD AND SNAP. WE LOAD THE TUBES (ON AVERAGE 2 TO 3 MTR LENGTHS) ON TO A RACK. ROLL THE RACK INTO A ELECTRIC ELEMENT FURNACE (3.4 MTRS LONG) WHEN THE TEMPRETURE REACHES 550DEG C THEN THE RACK IS REMOVED, THE TUBES ARE LIFTED OUT OF THE RACK USEING CHAINS AND A HOIST AND THEN LOWERED INTO A WATER BATH TO QUENCH WE ARE LOOKING FOR A MORE ACCURATE WAY OF ANNEALING TO IMPROVE OUR QUALITY AND PREVENT CRYSTAL REGROWTH. ARNE HERZ ENGINEERING - JOHANNESBURG SOUTH AFRICA

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