Welding on silver alloys
The challenge
Silver is difficult to weld due to its physical properties, regardless of the type of welding equipment used.
The very high thermal conductivity is particularly problematic.
The welding energy that is supposed to melt the metal is dissipated very quickly.
This results in rather small welding spots with little depth effect.
Tips
In any case, silver is easier to weld when it is warm, as the high thermal conductivity has less of an effect as the temperature rises.
Therefore, if possible, make several or many welding spots in succession to heat the area to be welded.
As welding wire, we generally recommend alloys of the same type or, even better, Lampert welding wires with optimum flow properties.
Welding of thin silver parts
This effect is less noticeable with small or thin silver parts, as there is no metal volume to allow the heat to dissipate too quickly.
Eyelets or thin silver parts can therefore be welded very well with a PUK device.
Set power
If you now work with higher power on silver to avoid this effect, the metal is locally overheated due to the low melting temperature and holes are created.
Although the metal is liquefied, it splashes away and craters form. With a PUK 3 Pro Plus you can use up to approx. 45% power for welding silver, higher power has a negative effect.
(With the PUK 3 professional this corresponds to approx. 60%)
Set program
With the specially modulated silver pulses of PUK 3 and PUK 3s, the energy is the energy is introduced into the metal in a controlled manner, largely compensating for the disruptive physical properties of the silver alloys!
These modes also allow clean and stable welds on silver.
Welding
However, please note that the penetration depth is still less than with gold or steel.
You should already take this into account when planning the workpiece and, where possible, butt weld from both sides or work with a V-joint.
Tack welds also hold in the event of severe distortion. It can be advantageous to spot weld larger silver parts with a slightly longer pulse time (12 – 18 ms), as this has a positive effect on the microstructure.
Use lead wire
With silver, a slightly shorter pulse time should be selected when adding wire!
(5 ms)
Working with filler material or welding wires is useful on many occasions.
Not only when pores need to be filled.
When welding larger parts, a better depth effect and stability can also be achieved and tack welds hold even with strong heat distortion.
Drawing and modeling
Select a thin wire, 0.2 – 0.4 mm, as an addition. The thicker the wire, the more power you need to use.
Drawing and modeling the deposited material, as we know it from gold alloys, is not possible with silver, as it cools down too quickly.
Due to its physical properties, silver tends to be pushed away by the welding energy.
We therefore work with silver in the opposite way to gold alloys – we drive the molten metal in front of the electrode tip.
Metal that is melted too high can also be pressed flat using this technique.
To do this, use a little more power and place the electrode almost vertically on the metal mound from above.
Smoothing material
To smooth the metal, proceed in the same way.
Again, use slightly less power and place the electrode vertically next to the applied silver.
This melts both the applied silver and the substrate, creating a firm and smooth bond.
