O P T E K
D P L - 2 4
7
PRINCIPLES OF OPERATION (CONTINUED)
When the cycle starts, vacuum is drawn on both ports, above and below the diaphragm.
Utilizing a high volume vacuum pump, an end point approaching two Torr is achieved.
This vacuum is displayed on a digital gauge located on the front panel. A programmable
timer adjustable from .1 seconds to 9990 hours determines the vacuum dwell time before
continuing to the next step
Figure 2
. It is important to note that this dwell time will
allow air between the layers of material to be evacuated before the lamination pressure
cycle begins, eliminating trapped bubbles. Because the vacuum is equal above and below
the diaphragm, it does not move and does not contact the material in the drawer.
At the end of the Vacuum Dwell, positive air pressure at up to 10 PSI is
applied to the port above the diaphragm bringing the pressure differential to nearly
25 PSI. see
figure 3
, The preheated silicone rubber diaphragm descends onto the
workpiece. This action drives the spring-mounted drawer platen into contact with
the lower heater platen. Isostatic pressure is transferred to the material by the
diaphragm. The stretching effect that occurs with roll type laminators is minimized.
The flexible diaphragm conforms to the surface shape assuring positive contact
between the layers, thereby eliminating voids. The pressure dwell time is controlled
by another timer identical to the vacuum dwell timer.
