Ultrasonic Welding Trouble Shooting Guide
PROBLEM PROBABLE CAUSES SOLUTIONS
Overweld Too much energy into the part. Reduce pressure, trigger force and/or down speed
Weld time too long. Reduce weld time/energy/ collapse.
Too much collapse. Change to lower ratio booster to reduce amplitude.
Digitally reduce the amplitude %.
Use Amplitude Proﬁling.
Reduce down speed.
Change to lower gain horn if lowest booster is already in use.
Absolute distance too high.
Recalibrate absolute distance and adjust.
Underweld Insufﬁcient energy into the part. Increase pressure, trigger, and/or down speed.
Insufﬁcient weld time. Increase weld time/energy/ collapse.
Insufﬁcient amplitude. Use higher ratio booster to increase amplitude, if horn allows.
Change to higher gain horn if highest booster is already in use.
Energy loss into ﬁxture.
If ﬁxture is urethane, change ﬁxture to rigid material such as
aluminum, stainless steel.
Evaluate part ﬁt in ﬁxture.
Presence of mold release.
Eliminate use or clean parts after molding.
Absolute distance too low.
Increase absolute distance.
Moisture absorption by
Dry parts as required.
Non-uniform Warped part(s).
Check part dimensions and ﬂatness
Check molding conditions.
Use higher trigger pressure.
Non-uniform horn face amplitude.
Have horn tested (and modiﬁed if needed) to establish uniformit
Lack of parallelism between horn,
Shim ﬁxture where necessary, or level adjustable plate.
ﬁxture and part.
Check part dimensions/ﬂatness.
Insufﬁcient support in the ﬁxture.
Check part ﬁt with horn using carbon paper.
Improve support in critical areas.
Change to a rigid ﬁxture.
If large sections of urethane are deﬂecting, add rigid backup