Ultra-Spray - Ultrasonic Spray Technology

USI’s patented “nozzle-less” Ultra-Spray technology is revolutionizing the coating systems industry by providing a superior alternative to conventional ultrasonic spray nozzles and traditional air-atomizing spray nozzle technology.

How It Works

Ultra-Spray ultrasonic coating technology has three components: an ultrasonic transducer; a voltage-mode ultrasonic power generator; and an independent fluid applicator.

Spray Forming Head:
The ultrasonic transducer operates at a fixed frequency and produces vibrations with maximum amplitude at the tip of the spray forming head. The transducer consists of a converter and spray forming head; each operates at the same frequency. The converter uses disc-shaped piezoelectric elements, sandwiched between a cylindrical titanium front section and a steel back section, to convert high frequency electrical energy into high frequency mechanical energy. The body of the spray forming head is shaped to concentrate the ultrasonic vibrations at the tip. To achieve ultrasonic amplification through the body the spray-forming tip must be narrower than the end that attached to the ultrasonic transducer. The spray forming head is shaped with a profile that can be stepped, linear, exponential, or Catenoid.

Ultrasonic Power Generator:
The ultrasonic power generator provides the power required by the converter; it supplies a constant sinusoidal voltage at the converter’s operating frequency. The power generator tracks the transducer’s power demand by adjusting the operating frequency and power factor as required by temperature and load changes. Load changes occur when more or less liquid is being sprayed from the atomizing tip. The amplitude of the sinusoidal voltage is also adjustable so that the amplitude of the vibrating tip can be optimized for the liquid being sprayed.

A microprocessor monitors these dynamic conditions and adjusts the generator to maintain optimum transducer operation. If an overload condition occurs, the power generator turns off and indicates a fault condition on the display.

Fluid Applicator:
The fluid applicator delivers liquid to the atomizing tip and directs airflow to shape and add momentum to the ultrasonically produced spray. The fluid applicator is comprised of a liquid applicator and an air director.

The liquid applicator supplies liquid to the atomizing tip in an even flow to match the width of the spray forming head. The output surface of the liquid applicator is positioned adjacent to the spray-forming tip so that the liquid flows easily onto the atomizing tip. There, the liquid forms a film over the tip area and is disintegrated into small drops by the ultrasonic energy. The resulting spray pattern is a uniform sheet of spray equal to the width of the spray forming head. The ultrasonic energy propels the spray from the atomizing tip.

The air director produces a directed air stream to shape the spray to the desired pattern and to provide additional momentum to the ultrasonically produced spray. The air director can be used to either focus the spray to a smaller pattern or to expand the spray to a larger pattern, depending upon the spray head and fluid applicator design.

Ultra-Spray Head – Type

		USI Sprayhead

The spray-forming tip has a rectangular shape about 38 mm wide. The fluid applicator is made up of a liquid applicator and two air directors.

The liquid applicator supplies liquid to the atomizing tip in an even “slot flow” to match the width of the spray forming head. The output surface of the liquid applicator is positioned adjacent to the spray forming head so that the liquid readily flows onto the atomizing tip. As the liquid flows onto the atomizing tip, it forms a film over the area of the tip and is disintegrated into small drops by the ultrasonic energy. The resulting spray pattern is a uniform “sheet” of spray equal to the width of the spray forming head. When the head is oriented such that the spray is in the upward direction, the spray will be propelled about 50 mm above the atomizing tip in a uniform sheet by the ultrasonic energy alone. Air directors are used to expand and propel the spray further from the spray forming head.

The air directors expand and shape the spray so that the sheet like spray pattern can cover a larger width at distances greater than two inches from the spray head. The spray width expansion factor is 1.5 times per inch of distance from the spray head up to about 200 mm between the spray head and substrate. The air director flow adds momentum to the “soft” ultrasonically produced spray to give the drops enough force to overcome ambient air currents. For example, when used to apply flux to printed circuit boards as part of the wave-soldering process, the spray has sufficient force to penetrate the through holes and vias to facilitate excellent soldering results.

Attributes of the Stepped Blade Head include:

1. No moving parts or seals – the spray head has no moving parts or seals and does not require disassembly for routine cleaning.
2. Non-clogging – there are no exposed small orifices.
3. Independent control of liquid flow rate and spray velocity – since ultrasonic energy is used to atomize the liquid and sir is used to shape the spray, the liquid flow rate and the spray velocity are independently adjustable.
4. Rectangular spray pattern – the rectangular spray head and the two air directors produce a rectangular shape coating deposition, which is ideal for producing a uniform coating on a flat surface.
5. High transfer efficiency – the transfer efficiency is better than 90%, meaning that less than 10% of the amount of spray liquid is wasted.
6. Powerful ultrasonic output – the ultrasonic energy is sufficient to atomize liquids such as high solids fluxes and adhesives.
7. Titanium spray head – aggressive liquids such as water-soluble fluxes or acids do not affect the titanium spray head

Applications

Smart Motion

Smart Motion traversing mechanisms allow for programmable speed and position control of the spray head, with sufficient "Motor Muscle" to ensure repeatable and dependable reciprocation for thousands of kilometers of movement. The Smart Motion System consists of either a servomotor or stepper motor coupled with a synchronous belt drive linear actuator. The speed and position of the Ultra-Spray head assembly are synchronized with conveyor speed and circuit board position to ensure an ultra-uniform application of flux. USI's Smart Motion systems are the most dependable motion control systems for spray fluxing applications available to industry.