Registrieren | Einloggen Derzeit keine Preisbindung

The World of precious Metals

Basic Information on Hard Soldering

The technique of hard soldering with silver hard solders of a low melting point and coordinated fluxes has seen a significant upturn in industry and craft all across Europe in the past 25 years.

Hard soldering has its place alongside the numerous welding processes in all areas of metalworking industry and installation work for years. Hard soldered connections are applied in because of their good strenght properties to an increasing extent.

Hard soldering means soldering with solders of a liquidus temperature that lies above 450 ° C. In practice, the operating temperature is higher than 600 ° C. Hard soldering differs from welding in that:

  • The melting temperature of the solder is lower than that of the base material.
  • At soldering temperature the liquid solder wets the base material and fills the solder gap by "capillary force".  

In the following table further important differences between soldering and welding are opposed to each other.

FeaturesGas Welding

Hard Soldering
(gap soldering, flame soldering)

base materialmetals of the same type or of simmilar typesmetal combinations
formation of the gaprelatively rough formationprecise formation
basic technique of the joining processfusing of base materialswetting of base materials
temperaturehigh melting temperature (base material)low operating temperature (solder)
filling the jointwith the aid of gravitywith the aid of capillar filling pressure
appearence of the jointshape of a caterpillarsmooth
handeling of auxillaries in  the form of rodswelding rod is moved along the jointsoldering rod is positionated at the soldering gap
kind of heatingdot like, welding bathevenly over the area of the soldering joint
type of flamessharp flamemostly soft, wide flame
moving the burnerprogressing straightly or shaped like a pendulumover a wide area