Bridging the Gap

A new bell atomizer designed to bridge the gap between affordable, low-maintenance conventional/HVLP spray gun applicators and technically superior but more costly high-maintenance bell atomizers has been developed by ABB Inc., Robotics Div. (Auburn Hills, MI).

According to Paint Business Development Manager Mark Freels, ABB’s Mini Bell will allow users who currently have conventional spray guns fitted to automated gun moving devices, such as reciprocators and robots, to switch to an alternative application method that can apply a higher-quality finish and increase transfer efficiency (TE).

“Bell atomizers were developed after standard spray guns,” Freels explains. “Bells were originally developed to be used at the highest end of the quality coatings application market, such as in automotive body panel finishing. They apply paint through a ‘bell cup’ rotating from 30,000–70,000 rpm. The control parameters applied to paint leaving the bell cup—cup rotation speed, fluid flow, and shape air—are what enable the bell applicator to deliver such a high standard of coating application control.”

Freels says the Mini Bell is designed to provide users with several benefits traditionally associated with bells at a general industry price tag. “With rotating bell cup atomizer technology, tighter control of particle distribution is possible,” he explains. “With the soft pattern application of bells and the wide range of bell cups available with the Mini Bell, high transfer efficiency can be maintained. Conditioned air flows can be reduced to allow the soft pattern, low-fluid-flow application utilized with bells, saving energy costs.”

According to Freels, the non-electrostatic Mini Bell can be thought of as a “bridge” between conventional spray guns and traditional bell atomizers. “Users still get higher-end functionality normally associated with an electrostatic bell atomizer, just not the highest possible TE associated with electrostatic bell atomizers,” he says. “With no high voltage, there is no need for users to make additional safety investment over their current automated systems.”

When voltage is used in the spray environment additional safeties, such as IR detection and deluge systems, must be put in place depending on local regulations, Freels says. But the non-electrostatic Mini Bell requires none of these safety measures, enabling users to swap out conventional spray guns for the bell and continue production with no safety upgrades needed. The bell also allows customers to spray solvent-borne or waterborne materials without worrying about issues related to spraying of waterborne materials in a high-voltage environment.

The Mini Bell is extremely small and light-weight compared to traditional bells. It weighs 2.5 kg and can be mounted on the lightest-duty painting robots available, which would be unable to handle the extra mass of conventional bells. It is available with 15, 30, 60 and 70-mm bell cups. Maximum flow rate is 400 cc/min, bell rotation speed range is 35,000–60,000 rpm, and the unit is 132 mm long × 90 mm diam.

Freels says the unit’s very low weight and available 15-mm bell cup will enable users to apply bell technology in very small, single-part flow applications such as painting of components for laptop computers and cell phones as well as small castings.