Instruction Manual
TE470/TE480
S.p.A.
25/52
2.7 – CURRENT STEPPER FUNCTION
The stepper function enables to compensate the wear of the electrodes that affects the quality of the welding
spots. When the electrode diameter is enlarged, the contact section area between the electrode and the work
piece to be welded increases and, as a consequence, the welding current density (Ampere/mm2) decreases. If
the current adjustment is maintained at a fixed value throughout the whole electrodes life, it will be noticed that
the quality of the last spots is poorer than the first ones. The stepper function is used for overcoming this
problem. It gradually increases the current adjustment during the welding process when the diameter of the
electrodes increases: this enables to maintain a constant current density.
An increment curve is programmed to describe the pattern of the current during the electrodes' life. This curve is
described by one or more segments for each of which the number of welding spots and the associated current
increment in percentage are programmed.
After it has been set, the current increment is applied to all the welding programs used.
If the current or conduction angle limits are used, they will be increased by the same percentage, as are the
settings for the pre-welding current and post-welding current, and the energy level to attain.
During the welding process, it is possible to correct the stepper curve trend by changing the parameters
determining its trend.
In order to start a new stepper curve, it is necessary to clear the counter and restore the starting
diameter of the electrodes.
SIMPLIFIED USE OF THE STEPPER FUNCTION (LINEAR STEPPER)
It is possible to use this function in a simplified way i.e. by programming a simple percent increase to be applied
to a predetermined number of welding spots, which must be carried out with the same electrodes.
To adjust these parameters, it is necessary to know first the electrodes life. Welding tests are carried out with
new electrodes and before their replacement. In both cases, the currents which are necessary to carry out the
welding process at the required quality are determined. Calculate the percent variation and set it up in the
control unit.
The parameters enabling the stepper function are included in the set-up menu. The relevant paragraph shows
how to program these parameters.
In order to use the "simplified" stepper function, always set the parameter INCREM. N. to 1 (because only one
segment is programmed).
In the SPOTS 1 parameter, enter the number of welds to be carried out, i.e. the foreseen lifespan of the
electrodes.
In the INCREMENT 1 parameter, enter the intended percentage increase.