Page 114 - SSAB Welding Handbook Edition 2

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19.0 Stud arc welding Welding handbook

The principal steps in all mentioned types of stud 19.7 Precautions prior to welding
arc welding involve:
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The studs and ferrules should be kept in a clean, dry
1. Positioning of the stud and the gun.
location and in accordance with their manufacturer
2. Activation of the welding process. Upon contact, in order to prevent discontinuities such as hydrogen
the stud is raised, ignites the arc and a liquid weld cracks in the joint.
metal is formed. The stud serves as an electrode
and is molten during welding.
As in other welding techniques, the surface should
3. The arc ceases after a preset period and the stud be free from contaminants like oil, water, rust and
is punched down into the liquid weld metal. mill scale prior to welding in order to prevent
4. The weld metal cools and solidifies. The welding discontinuities in the joint.
process is finalized.
A sufficient electrical contact between the stud
Fig. 19.5 illustrates these sequences for the different and the work piece is needed in order for ignition
stud arc welding methods. The short cycle method of the arc. The welding equipment normally has
in this example is performed without a ferrule or a an indicator that signals if a satisfactory electrical
shielding gas. contact is attained. Welding on a shop primed steel
surface is sometimes feasible and at other times, it is
not. If there is a lack of electrical contact, the primer
The arc voltage is based on the welding conditions can be easily removed from the location of the stud
and is automatically set by the welding equipment. weld and the work piece connection with, for
Increased voltage values correspond to an increased instance, a brush. Modern equipment may be
lift height of the stud.

Stud welding with ceramic ferrule
Stud holder

Ceramic Stud holder
ferrule
Workpiece

Stud welding with shielding gas
Stud holder
Protective
gas shroud
Shielding
gas Stud
Workpiece

Short-cycle stud welding
Stud holder
Adjust
screw

Stud Workpiece

Stud is positioned Stud lifted off, electric Stud immersed in Stud is welded
arc is ingnited liquid weld pool

Fig. 19.5: The different welding sequences for each stud arc welding method. The short cycle method in this example is performed without
shielding gas.
114 This handbook contains general suggestions and information without any expressed or implied warranty of any kind. SSAB hereby expressly disclaims
all liability of any kind, including any damages, in connection with the use of the information and for their suitability for individual applications.
It is the responsibility of the user of this brochure to adapt the recommendations contained therein to the requirements of individual applications.