What is Stud Welding?
Stud welding is a fast, reliable
and accurate method of welding a metal fastener to another metal object.
The resultant weld joint is stronger than the stud or parent material.
Improved product design is achieved since reverse marking is eliminated
and the area around the stud is flat and clean.
In order to weld the stud,
access is only required from one side which means that component handling
is reduced. Welds are also leakproof and tamper proof, and since no
holes are punched in the sheet, corrosion problems are reduced and the
work piece is not weakened.
Stud welding can also be
used on single sided pre-coated polished or painted materials. The fastener
can be made from many metals or alloys.
Stud welding benefits: Fast attachment. No reverse marking. The welded
joint is stronger than the parent material or the stud. Access is
only required from one side. No holes hence no leaking or weakening
of the sheet. Tamperproof. Pre-coated or painted materials can be
welded. The equipment is portable and easily jigged. In fact Stud welding
overcomes all of the disadvantages of the following problems.
Problems with Alternative Fixing and
Fastening Methods
Drilling and Tapping: These processes are very slow. Thicker parent material and longer studs are required.
Inserts:
They can eventually work loose. They can crack paint and leave unsightly
stains. Holes need to be deburred in parent material. The reverse
side is not always clean and flat. The parent material is weakened
by holes.
Back Welding:
The process is slow. Holes need to be punched and deburred
in parent material. The excess weld needs grinding off for a clean
flat finish. The parent material is weakened by holes.
Through Bolting:
Requires two handed assembly and access from both sides.
Holes need to be punches and deburred in parent material. Bolt heads
are unsightly and stains can come from the bolt holes. The assembly
is not leakproof and the parent material is weakened by the presence
of holes.
Capacitor Discharge "CD" Welding Processes
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The capacitors
are charged to a pre-set voltage to suit the diameter to be welded.
The stud pip is placed into contact with the sheet. |
Upon triggering,
the stored energy is discharged as a high current pulse, melting
the pip and producing an arc. |
Return spring
pressure forges the stud into the molten surface area on the sheet
to give complete fusion across the flange. |
Designed
specifically for thin gauge materials where reverse marking must
be minimal. Sheet surface should be clean and flat. Stud has a weld
pip. |
Stud/Material/Power
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Advantages
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Stud Diameter 1mm - M10 |
Low
cost equipment, low cost studs, fast to load and weld, easy to jig
and automate, small light equipment, no ferrules or shrouding gas
required, good weld results with aluminium or brass in addition
to mild and stainless steel. Weld is clean and requires no finishing |
Material
Thickness 0.7mm & above |
Power
Requirements Single Phase 240/110 Volt |
Drawn Arc "DA" Welding Processes
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Current
and weld time is pre-set to suit the diameter to be welded. The
stud is then placed on the plate |
Upon
triggering, a pilot arc occurs as the stud lifts to a pre-set height.
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The
main arc then melts the weld end of the stud and creates a molten
pool in the plate |
Return
spring pressure forges the stud into the molten pool. The ferrule
contains the molten metal and shapes the fillet |
Very
strong penetrative welds are achieved with this process. Ferrules
required to contain and shape molten metal. Weld end of stud is
fluxed. |
Stud/Material/Power
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Advantages
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Stud Diameter
3mm
to 30mm
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Burns
through parent material laminations, tolerates surface curvature
and imperfections e.g. light rust, scale, grease and some coatings.
Gives neat and controlled weld fillet. The only method of stud welding
large diameters. This process also lends itself to multi-gun applications. |
Material
Thickness 2mm & above |
Power
Requirements Three Phase 415 Volt |
Short Cycle "SC" Welding Processes
This process
is the same as for Drawn Arc, but operates over a much shorter time
period - up to 100 milliseconds. Ceramic arc shields (ferrules)
are not required with this process, but shrouding with gas can improve
weld fillet formation especially when welding stainless steel studs.
Capacitor Discharge studs may be used. |
More
penetrative welds than CD and is suitable for hot rolled/coated
materials. |
Stud/Material/Power
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Advantages
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Stud Diameter
M3
to M8
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This
process is more tolerant than CD of uneven or dirty surfaces. Can
be easily automated and can utilise low cost CD studs. Ferrules
are not required, however shrouding gas improves weld spatter
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Material
Thickness 1.5mm & above |
Power
Requirements Three Phase 415 Volt |