Parameters that can be directly or indirectly controlled in this system and their operating
range for stable spray conditions are listed here:
2) Type of atomizing gas: In this study, dry air and nitrogen were used.
3) Pressure of the atomizing gas: The pressure of the atomizing gas determines its
volume-flow-rate and thereby its velocity in the nozzle region. The maximum gas
pressure that can be used is limited by the laboratory’s air compressor unit
(Airtower26, KAESER). The minimum gas pressure is restricted by the stability of
6) Arc current (indirectly controlled): The current that passes through the wires and
maintains the arc, ranges from about 150 Amperes to about 300 Amperes in the
ValuArc 200 spraying system. This current is determined by other operating
parameters.
The next two sub-sections discuss how these operating parameters interrelate.
2.2.1 Volume-Flow-Rate
Volume-flow-rate of the atomizing gas and its pressure were measured using the external
flow-meter (MEM Thru View, Meter Equipment Manufacturing, Inc., OH) and pressure gauge
installed between the flow-meter and the gun. These measurements are plotted in Figure 2.13 for
air as the atomizing gas. It can be observed that volume-flow-rate increases linearly with
pressure. Since the arcing occurs downstream of the nozzle, this relationship is not significantly
affected by other operating parameters (i.e. voltage, wfr, wire material).
the spray system. Overall, the gas pressure in the ValuArc 200 spray system can be
varied between 20 psig (239 kPa) and 65 psig (550 kPa).
4) Voltage applied on the wires: The applied voltage in the ValuArc 200 spraying
system can be varied from 20 V to 40 V.
5) Wire-feed-rate: wfr in ValuArc 200 spray system can be varied from 3 m/min to 11
m/min. (5 cm/s to 18 cm/s)