NOTE: If a suitably powerful welding machine is not available and multi-layer panel joints
with a total thickness of over 3 mm need to be made, puddle welding must be used.
Although in principle, high and super high-strength panels are adequately or well suited to
resistance spot welding, considerable problems may arise because of low welding power,
especially where thicker panels or three layers of panel must be welded together in the
workshop. In particular, older welding equipment does not have the latest welding
technology nor welding power and therefore cannot reliably join panel thicknesses greater
than 3 mm.
Equipment with inverter technology allows better spot weld quality because of a constant
high welding current. In addition the high welding current makes shorter welding times
possible and the electrodes therefore have a longer working life. Inverter welding is a
further development of electrode welding.
Further advantages of the new inverter welding equipment are:
good welding performance with constant quality, even with high switch-on times
recognition of and compensation for disruptive factors: e.g. primer, adhesive, rust-
prevention paint
own and pre-set welding programs which can be saved and called up
quality confirmation through logging of all important welding data
fast changing of spot welding clamps or spot welding guns as required
The following functions can be controlled and monitored by programming the welding
equipment:
Control of the start conditions by resistance measurement (dirt, paint, bodywork
adhesive, shunt circuit through the next spot weld).
Ensuring the optimum welded connection.
Checking the energy balance, resistance and quality.
In the case of resistance spot welded connections, faults in the weld are difficult to see
from the outside. It is therefore absolutely vital to know the particular properties of the
welding machine being used. A test weld with subsequent peeling test will provide
information on the quality of the weld. The spot weld itself must not separate, it must tear
away leaving a hole.
In the production of vehicle bodies, MIG welding plays a minor role as a joining technique.
It is used for components subject to high demands, such as threaded plates for axle
mountings, or at locations which cannot be spot welded for access reasons.
Description
Description
1
MIG welding machine
2
Resistance spot welding machine