DCM00003 REV. 07 11
When producing an ultrasonic weld, there are three primary variables that interact; they
are:
Time: The duration of applied ultrasonic vibration
Amplitude: The longitudinal displacement of the vibration
Force: The compressive force applied perpendicular (normal) to the direction of vibration.
Power required to initiate and maintain vibration (motion) during the weld cycle can be
defined as:
P = F x A
Where:
• P = Power (watts)
• F = Force * (psi)
• A = Amplitude (microns)
Energy is calculated as:
E = P x T
Where:
• E = Energy (joules)
• P = Power (watts)
• T = Time (seconds)
Thus the complete ‘Weld To Energy’ process would be defined as:
E = ( F x A ) x T
A well designed ultrasonic metal welding system will compensate for normal variations in
the surface conditions of the metals by delivering the specified energy value. This is
achieved by allowing Time (T) to adjust to suit the condition of the materials and deliver
the desired energy.
Welding To Energy - Why?
Most metal welding applications are produced by ‘Welding To Energy’ in order to
compensate for the various surface oxides and contaminants associated with the metals
being joined. In a few applications ‘Welding To Time’ or ‘Welding To Height’ will yield better
results. Since the majority of all metal welds are produced using energy as the controlling
factor we will confine our discussion to that condition.
Welding to energy is necessary because of the non-metallic oxides that form on the
metal’s surface as well as other contaminates such as grease and dirt. To producing
quality welds reliably it is necessary that the surfaces to be joined are clean. The high
frequency scrubbing action, combined with pressure, cleans the weld interface at the
beginning of the weld process.
NOTICE
Force is determined by multiplying:
Force = (Surface Area of the Cylinder) X (Air Pressure) X (Mechanical
Advantage)
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