Dukane ULTRASONIC GENERATOR/POWER SUPPLY LS 403-574-01 - Manual (Page 71)

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Section 9-Maintenance
Dukane Manual Part No. 403-574-01
Welding Problems
Weak Welds
Weak welds, or underwelding, is caused by insufficient
energy being transmitted to the part. You can increase
the weld pressure, increase the weld time or change to a
higher gain booster to increase the amplitude to increase
the energy delivered to the weld.
Excess Flash
The energy director may be too large. You can try to
reduce the weld pressure and/or weld time. The parts
may have too much shear interferences or a nonuniform
joint dimension.
Inconsistent Welds
Variations in plastic due to filler materials and moisture
absorption may lead to inconsistent welds. Fillers can
be especially troublesome if they are not uniformly
distributed, the content is too high or it contains too
much or poor quality regrind or degraded plastic.
Check the horn and fixture alignment and parallelism.
Check the alignment of the mating parts, shifting during
welding or residual mold release on the parts.
Try welding by energy. This eliminates many
inconsistencies. There should be no unusual or loud
noise from the acoustic stack. If there is, disassemble
the stack and reassemble.
Exchange the probe with another unit to see if the problem
disappears. If not, exchange the generator with another
unit to try and isolate the problem.
The horn amplitude may not be uniform if it has been
machined, altered or damaged. All of these will change
the resonant frequency of the horn. You can have the
horn analyzed.