It is essential that the mating faces between an ultrasonic
transducer/booster and a booster/horn be absolutely flat
and parallel. If there is any air gap, there will be a loss in
power output and efficiency. Coupling may be so poor as
to prevent the startup of vibration from the stack, due to
the excessive power draw at the mating surfaces.
The condition of excessive crowning, or uneven contact
surfaces, is normally made evident by a burnished
appearance around the bolt hole areas of the contact
surfaces. This condition indicates that contact between the
parts occurs only at the burnished areas and not across the
full faces of the mating surfaces. See Figure 8-1.
The following flatness tolerances are specified for
Dukane transducers, boosters, and horns used in 20 kHz
applications:
Transducer
.0005 inch
Booster
.0005 inch
Horn
.0005 inch
To check if there may be a flatness problem, first
disassemble the stack and look at the mating surfaces.
If there are burnished areas at the periphery of a contact
surface, that surface may be crowned in the center. Place
a straight edge along the face. Refer to Figure 8-2. If light
can be seen along the edges, it is crowned.
The surface may also be depressed in the bolt area. Refer
to Figure 8-3. In this case, there will be contact only at
the peripheral edges and light will be visible beneath the
straight edge in the center region.
Crown
Straight
Edge
Gap
Straight
Edge
Gap
Burnished
Area
Figure 8-3
Example of Center Depression
Figure 8-2
Example of Crowning
Figure 8-1
Example of Burnished Area
Inspection of the Acoustic Stack Components
Page 91
Dukane Manual Part No. 403-594-02
Section 8 - Stack Maintenance
