Instruction manual
ITEM TE550
S.p.A.
2.8
- 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 INCREMENT)
The stepper function can be used in a simplified manner by programming a simple percent
increment for a specific number of welding spots that are to be carried out with the same
electrodes.
STEPPER MENU
>TOTAL STEPS 1
SPOTS 1 02000
INCREMENT 1 26
%
The user must know the service life of the electrodes in order to adjust these parameters. To
do this run some welding tests with new electrodes before they are replaced. Under these two
conditions the currents, required for carrying out the welding spots of the required quality, are
assessed. The change in percent is calculated and then it is set in the control unit.
The parameters that allow the carrying out of the stepper function are entered in the
“
STEPPER MENU
”. The instructions for programming these parameters are outlined in the
relevant paragraph.
For the “simplified” use of the stepper function, always set parameter TOTAL STEPS to 1
(since the segment to be programmed is only one). Enter the number of welding spots to be
carried out in parameter SPOTS 1, i.e. the foreseen life span of the electrodes. Enter the
percent increment to be achieved in parameter INCREMENT 1.
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