8 января, 2016 
Pokraskin A method sometimes used is to check the pressure-time response of the adhesive dispense valve.
In a pressure-time dispensing system (see Section 8.3), the adhesive is forced under pressure through a valve so that the desired quantity is dispensed onto the component part. As the dispense valve opens and closes, the pressure-time response curve can be monitored just upstream of the nozzle tip.
Figure 10.2 shows a typical pressure-time output as the valve operates. There is a brief surge in pressure as the valve opens and then this levels out fairly quickly until the end of the elapsed dispense time. If there is a bubble in the adhesive or a blocked nozzle the pressure-time curve will be changed (Figure 10.3) and by integrating the area under the curve, the software controller [1] can quickly determine whether the dispensed quantity was within preset tolerances.
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