Amada 1-288-01, Operation Manual, Page: 60 / 144

CHAPTER 4: INTRODUCTION TO FEEDBACK MODES AND MONITORING
HF28 DC RESISTANCE WELDING SYSTEM
4-6 990-372
Active Part Conditioning Waveform
The use of a current limit monitor for the first pulse enables the pulse to be terminated when a
predetermined amount of current flow is achieved. The rise of the current waveform is proof positive
that the oxide is breaking down and the parts are fitting up together, ready to weld. The first pulse,
therefore, should be programmed to be much longer than generally required. The power supply will
terminate the pulse based on the reading of current in the power supply’s monitor.
2. Resistance Set
Application

Reduce variations in Resistance prior to the weld

Reduce contact resistances before delivering the main weld energy.
Description
Resistance Set is used when parts vary in initial resistance due to:

Shape and part fit up

Very small parts
Resistance Set
is very similar to
APC
except that there are applications where you do not want a high
voltage at the beginning of the pulse. Instead, you want to start both voltage and current low and build
on an upslope. This would be used primarily where resistance would vary from weld to weld, coping
with material contamination, and variation due to part fit up problems. It can be programmed to apply
the exact power to the parts required to reduce the resistance to a consistent level for every weld.
Resistance Set
uses a dual-pulse output. The first pulse is programmed for
upslope power
, and the
second for either
constant current, constant voltage
, or
constant power
. (
Constant voltage
is used if
there is still a chance of weld splash). The purpose of a dual-pulse operation is to enable the first pulse
to target variations in resistance; the second pulse achieves the weld.
Resistance Set Waveform
The use of a current limit monitor for the first pulse enables the pulse to be terminated when a
predetermined amount of current flow is achieved. The rise of the current to a consistent level ensures a