Glossary of Terms
9-2 Digital Compact
Distance welding
In this mode of operation a predefined distance (vertical feeding motion
of the horn onto or into the workpiece) is effected and during that time
ultrasonics is output.
Down Speed
The velocity at which the acoustic stack descends to the part.
Dynamic Trigger
See Trigger.
Energy director
Projection at the parts to be joined, enabling high energy density in the
joint area. A V-shaped projection of plastic material at the otherwise flat
joint area of the lower part to be welded, ensuring that at the beginning
of the weld cycle, the contact between the two parts is restricted to a
line. This contact is heated rapidly and starts melting. Because of an
increasing so-called damping factor, more energy is transformed into
heat. This causes the material in the joint area to melt more rapidly.
Energy welding
In this mode of operation, the weld is controlled by the energy (in
joules) transferred.
Far-field welding
Welding at a distance greater than 0.25 inch (6mm) from the point of
horn contact with the workpiece. In this mode of operation it must be
ensured that the walls of the plastic part can transfer the ultrasonic
energy to the mating surface without loss if possible. Compare near
field welding.
Flash
Material displaced from the joint area.
Frequency
The number of vibrations released by the ultrasonic power supply or
the converter per hour. The respective unit of measure is hertz (hz). In
welding of plastics, the frequencies applied are usually 20, 30, or
40 kHz.
Hold Force
The force applied to the part during the hold portion of the cycle.
Hold time
The time after the weld has ended during which the molten mass in the
joint area solidifies and hold force is applied to the part.
Horn
Welding tool that concentrates and amplifies the mechanical vibrations
and transfers the vibratory energy to the joint area.
Mating surface
Refers to the mating surfaces between converter, booster, and horn, as
well as to the ones between the horn and part, or between upper and
lower part.
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