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electrode faces are smooth. If this is not done, the rough surface of the electrode face will have a
tendency to stick to the work piece.
Weld Schedule Development
Developing a weld schedule is a methodical procedure which consists of making sample welds
and evaluating the results. The first weld should be made at low energy settings. Adjustments
are then made to each of the welding parameters one at a time until a successful weld is made.
1.
Install the correct electrodes in the electrode holders on the Weld Head. See the
preceding table for electrode material recommendations.
2.
Use a flat electrode face for most applications. Use a "domed" face if surface oxides are
a problem. If either of the parts is a wire, the diameter of the electrode face should be
equal to or greater than the diameter of the wire. If both parts are flat, the face should be
at least one-half the diameter of the electrodes. Pencil point electrodes cause severe
electrode sticking to the parts, unexplained explosions, and increase the weld heat
substantially because of the reduced electrode-to-part contact area.
3.
Use the Force Adjustment Knob on the Weld Head to set the Firing Force and adjust an
Air Actuated Weld Head per the manufacturer's instructions. Figure D-1 illustrates the
effect of weld force on the parts.
4.
Follow the "Getting Started" instructions in Chapter 3 to make your first weld. Always
observe safety precautions when welding and wear safety glasses.
5.
Use pliers to peel the welded materials apart. A satisfactory weld will show residual
material pulled from one material to the other. Tearing of base material around the weld
nugget indicates a material failure NOT a weld failure. Excessive electrode sticking
and/or "spitting" should define a weld as unsatisfactory and indicates that too much weld
current, voltage, power, or time has been used.
6.
If the parts pull apart easily or there is little or no residual material pulled, the weld is
weak. Increase the weld time in 1 cycle increments. Increase weld current if a satis-
factory weld is achieved using 10 cycles of weld time. Note: Actual weld strength is a
user defined specification.
7.
Polarity, as determined by the direction of weld current flow, can have a marked effect on
the weld characteristics of some material combinations. This effect occurs when welding
materials with large differences in resistivity, such as copper and nickel or when welding
IP-215A/IP-217A FINE SPOT WELDING POWER SUPPLIES
993-603 REV A: October, 1996
APPENDIX D: RESISTANCE WELDING BASICS
D-7
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