RESISTANCE WELDING AS CORE COMPETENCE

Resistance butt welding

With resistance butt welding, the abutting faces of workpiece 1 and workpiece 2 are connected at the joint by the introduction of sufficient energy and heating (resistance heating).

Resistance butt welding is typically used to produce closed rings. Variant diversity extends from round wires to flat strip material.

Mash seam welding

With mash seam welding, also referred to as lap welding, the parts that are pressed onto each other (overlapping surfaces of workpiece 1 and workpiece 2) are connected after adequate heating (resistance heating) of the joint.

Requirements and practical tips: Electrode material generally W or WCu, good electrode cooling, closing movement of electrodes parallel to welding seam

Projection welding

In projection welding the parts are pressed onto each other and connected through sufficient heating of the joint. The seam is heated (resistance heating) by concentrating the current in the welding projections. Geometric forming reduces the contact surface while increasing the transition resistance.

The current concentration is influenced by the shape and volume of the projection. Optimal adaptation of these two factors can critically influence the melting behavior of the material so an optimal weld quality with the longest possible electrode service life can be achieved.

Contact welding

Contact welding is a process for local application of precious metals that is derived from projection welding. In the area of industrial switching technology, precious metals, also referred to as contacts, ensure a lower contact transition resistance,  high welding resistance, good arc path and arc-extinguishing behavior, good burn-off resistance, high corrosion resistance and high thermal and electrical conductivity.

Contacts that are ready to be welded can either be purchased directly as platelets, or produced by cutting more attractively-priced semi-finished products (round wire, profile strip) to size. For optimal and flexible machining of any kind of semi-finished product, Bihler recommends the use of its contact welding devices that have been developed for this purpose.

Compacting strands

Compacting strands is the process of pressing single wires of a strand together and compacting them under pressure after application of heat (resistance heating). The joint(s) is (are) the contact surfaces (surface area) of the individual conductors.

Setting/compacting in a vertical direction is executed via the electrodes. This creates a weld on the stranded wire resulting in a bundle. It gives the stranded wire the optimum shape for subsequent welding tasks.

Nut welding

In nut welding the parts are pressed on top of each other (nut and carrier material) and connected through heating of the joint. The joint is heated (resistance heating) through the current concentration of the welding aids. This geometric forming reduces the contact area and simultaneously increases the transition resistance. In this regard the welding projection can be located on the nut and/or on the carrier strip.

Requirements and practical tips: Massive, stable welding gripper and tool design (high welding forces), exact, reproducible positioning of nuts, minimization of weld spatter through good feed behavior thanks to the gripper system as well as through precise adjustment of welding force and welding parameters

Resistance soldering

Solder additive required (normally L-Ag15P)

Large-area connections are possible (> 90%)

Mainly used for Cu materials e.g. switching contacts with fusion surface