Page 103 - CITS - Welder - Trade Theory

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