Nozzle design is the major factor in
any system that determines the type and quality of the pattern you obtain, and the cost of
the adhesive used.
At any time a nozzle becomes clogged or the pattern distorted, it should be replaced. The cost of a replacement nozzle is low compared to the work that may be rejected due to improper adhesive placement or adhesion failure in the field. Attempts to clean clogged nozzles with a probe will usually result in deforming the orifice and an improper extrusion.
Generally, it is preferable that the nozzle be as close to the work as is practicable, especially for high speed operations.
The orifice size selected should be as large as practicable to minimize clogging from foreign matter in the fluid. If the orifice is too small, high pressure is needed to obtain the required amount of adhesive, and the force of the adhesive stream may damage fragile substrates. If the orifice is too large, the stream may tend to waver or droop, resulting in improper placement of adhesive.
For correct placement of adhesive ejected from multi hole nozzles, high pressure and a relatively small orifice is necessary.