Welding or soldering: which joint is right for which job?

In principle yes, because the weld seam is made of the base material itself and can reach its strength, while a soldered joint has the strength of the solder, and that normally sits below. In practice it depends on the execution: a large-area brazed joint with a properly designed gap can carry more than a badly welded seam. The advantage of welding is that the joint matches the parent metal, with no foreign alloy sitting in it as a weak point.

The line sits at 450 degrees Celsius, measured at the liquidus temperature of the filler. Under DIN ISO 857-2 it is soldering when the filler becomes liquid below 450 degrees and brazing above that. Solders are mostly tin-based and give comparatively soft joints, brazing alloys based on silver, brass or gold give much stronger ones. The third level once in common use, high-temperature brazing above 900 degrees, comes from the withdrawn DIN 8505. The current terminology standard knows only the two categories, even though the term lives on in practice.

Yes, and that is one of the main reasons the process is used in jewelry. The pulse lasts only fractions of a millisecond up to a few milliseconds, the heat stays local and the component barely warms up overall. Resizing rings, adding prongs or welding on clasps is possible without unsetting the stone. Soldering would mean bringing the piece up to soldering temperature over a large area, which many stones do not survive.

In most repair and assembly jobs, yes. The gain is twofold: no foreign metal in the joint, so no visible solder seam and no different tarnishing, and no heat across the whole piece, so no stones to unset and less firescale. For capillary joints, gap bridging and large areas, soldering stays the right route.

No. Micro-TIG welding uses no flux, the argon does that job and keeps oxygen away from the melt. For the workflow that means a piece can be finished, set and polished and only then welded. With soldering the surface has to be rebuilt afterwards.

No, that almost always produces pores and inclusions. Soft solders contain tin and sometimes lead, brazing alloys contain zinc, older silver brazing alloys also cadmium. These elements boil far below welding temperature, vaporize suddenly and contaminate the weld pool. The solder residues have to be removed mechanically first, down to bare base material.

No. Under Annex XVII entry 23 of the REACH regulation, extended by Regulation (EU) 494/2011, brazing alloys and metal parts of jewelry with a cadmium content of 0.01 percent by weight or more may no longer be used or placed on the market. Jewelry already on the market before 10 December 2011, or more than 50 years old at that date, is among the exemptions, and it is exactly this older stock that arrives in the repair workshop. Where the origin of an old solder joint is unclear, the solder should be removed mechanically and the workplace extracted properly, because vaporizing it produces toxic cadmium oxide fumes.

Tack welding holds two parts in exactly the right position with short, high-energy pulses before they are soldered conventionally or worked on further. It replaces binding wire, clamps and holding compound and is therefore the most common combination of the two processes. Parameters and further cases are in the section combining both above.

In part. Related materials such as different stainless steels or gold alloys of different fineness normally join well. With very different metals brittle intermetallic phases form, and there soldering is often the better route because the solder wets both materials without melting them. For a specific pairing a sample weld is worth doing before going into series.

Not on the unit price per joint, but on the rework saved, the scrap avoided and the jobs that then stay in house. The individual items are in the section on cost above. Working complete setups start at around 4,400 EUR net ex works for the PUK, and leasing is available.