Amada 300 Series, Operation Manual

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CHAPTER 3: OPERATING INSTRUCTIONS
SERIES 300 FAST RESPONSE WELD HEAD SYSTEM
3-20 990-115
The Importance of Follow-Up Force
The programmable follow-up force is the key to high performance and consistent weld quality achievable
with the Weld Head System. Depending on the type of weld, the weld material melts or becomes plastic as
the weld progresses, causing the force between the electrodes to diminish. Unless the weld head can
quickly accelerate the electrode into the weld material during this crucial time period, material will be
expelled from the weldment, producing a poor weld. The small movement of the electrodes during the
course of the weld is called ‘follow-up.’ The ability to rapidly accelerate the electrodes during follow-up,
thus maintaining force on the weld material and preventing expulsion, is a key performance measure of a
weld head.
Conventional weld heads – whether pneumatic, pedal, hand, or cam operated – typically use a mechanical
spring or pneumatic cylinder to develop the weld force. The maximum follow-up acceleration is limited by
the moving weld head mass (including electrode, electrode holder, and output shaft) and the weld force.
The relationship between follow-up acceleration, weld force, and moving mass follows Newton’s first law
of motion: Acceleration = force/mass. Since the moving mass is constant for a given weld head, the
maximum follow-up acceleration is proportional to the weld head force. This means that for low force
welds, or for welds that require a lot of follow-up acceleration (such as wire-to-foil or cross-wire welds),
conventional weld heads have a fundamental limit to their follow-up performance.
The Series 300 Weld Head System, however, uses an electromagnetic linear actuator to develop the weld
force. A user-programmed force impulse (FWUP) accelerates the electrode into the material during the
follow-up period. The resulting precise head movement outperforms any other weld head technology.
Use the following procedure as a starting point to set up the FWUP force:
1 Start with default WELD, FWUP force, DLY and FWUP time settings.
2 Use the graphical setdown RUN screen and PROGRAM screen to assist in fine-tuning the programming
of the timing and magnitude of the follow-up force.
3 Make a few welds. Notice where the setdown displacement starts to change rapidly. This is the point
where the weld materials start to melt. Adjust the DLY to position the FWUP impulse at this point.
4 If sparking or splashing occurs, increase both the WELD and FWUP forces. To calculate the new
FWUP force, multiply 2.5 lbs./0.001 inch (44.6 kg/0.0254 mm) by the measured electrode displacement.
Add this new constant to the weld force value. Use the combined total as the new FWUP force.
5 For large WELD and FWUP force operations, increase the FWUP time to match the actual melting or
setdown period as indicated by the ‘S’ shaped portion of the actual setdown graph.
6 Experiment with the FWUP force, time duration, and delay time to optimize the weld.