Flux
Flux turns up in 2 fields: welding, mechanical. Here is what it means to the people in each one.
Flux in welding
Material that shields molten metal from air and cleans oxides, as rod coating, wire core, granules or paste.
Chemical mix that protects the molten pool, removes oxides and forms slag. It appears as the coating on stick electrodes, the core of flux-cored wire, the granular blanket in submerged arc, and the paste or powder used in brazing and soldering, where it dissolves oxide films so the filler can wet the metal. Most fluxes absorb moisture, which brings porosity and hydrogen cracking, so storage matters.
"Sub arc flux sat out in the rain overnight, scrap it, we're not rebaking that."
Flux in mechanical
The rate at which a fluid, particle, or energy crosses a specific surface area.
A measure of flow per unit area per unit time. In fluid mechanics and heat transfer, it quantifies how much of a continuous medium passes through a defined boundary. Calculating it allows engineers to size heat exchangers, determine cooling requirements, and evaluate mass transfer rates in piping networks.
"The heat flux across that copper plate is too high, so we need to add thermal paste or increase the surface area."