Page 103 - CITS - Welder - Trade Theory
P. 103

WELDER - CITS


           Copper Types- Properties and welding method

           Objectives : At the end of this lesson you shall be able to
           •   describe the various types of copper
           •   state the physical properties of copper
           •   explain the welding procedure.


           Electrolyte copper:
           This type contains 99.9% pure copper with 0.01 to 0.08% oxygen in the form of cuprous oxide.(Cu2O).

           This     type of copper is not weld able.
           De-oxidized copper:
           In this type a small quantity of phosphorous, a de-oxidizing element is added to the electrolyte copper.
           This type of copper is weld able.
           Characteristics of copper

           1  Reddish in colour.
           2  High thermal and electrical conductivity. Excellent resistance to corrosion.
           3  Excellent work ability in either hot or cold condition or informing wires, sheets, rods, tubes and castings.
           4  Melting point: 1083°C.  Density: 8.98g/cm3

           5  Coefficient of linear expansion (ic):0.000017mm/mm/°C
















           Edges preparation:
           a  Upto1.2mm - edge or flange point.
           b  Over 1.5mm up to 2.5mm - square butt with 50% of sheet thickness as root gap.
           c  2.5mm to 16mm - angle ‘V’ of 80°-90°.
           d  Over 16mm - Double ‘V’ preparation of 90°.
           Types of cleaning:

           Mechanical cleaning is done to removed it and any other foreign material. Chemical cleaning is done by applying
           solutions to remove oil, grease, paint etc.
           Filler rod and flux:
           A completely de-oxidized copper rod (copper-silver alloy filler rod) having a lower melting point than the base
           metal is used.
           Flux: Copper-silver alloy flux is applied on the edges to be joined in paste form.
           Nozzle size: Use a nozzle which is one size larger than that used for mild steel.
           Flame: Adjust a strictly neutral flame.
           Effects of setting ‘carburizing’ or ‘oxidizing ‘flame
           a  Too much oxygen will cause the formation of copper oxide and the weld will be brittle.



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                                            CITS : C G & M - Welder - Lesson 14-26                                                                              CITS : C G & M - Welder - Lesson 14-26
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