subject: Airless Painting Equipment - Leather Digital Watch Manufacturer - Digital Diving Watches [print this page] Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (September 2009)
It has been suggested that this article or section be merged into Spray_painting#Airless_spray_guns. (Discuss)
Airless spray is a method of atomizing paint without the use of compressed air. The paint is pumped under high pressure through a hose to an airless spray gun. The paint is forced at high pressure through a small opening at the front of the gun called the spray tip. This tip controls the flow of material and the fan width. Many different tip sizes are available.
Airless Spray have many advantages, such as:
Speed
Less overspray than conventional air spray
A thicker coat of material can be applied in a single pass.
High viscosity materials can be atomized without thinning.
Airless pumps can be powered by different types of motor: electric, compressed air (pneumatic) or hydraulic. Most have a paint pump (also called a lower) that is a double acting piston, in which the piston pumps the paint in both the down and the upstroke. Some airless pumps have a diaphragm instead of a piston, but both types have inlet and outlet valves.
Most electric powered airless pumps have an electric motor connected through a gear train to the paint piston pump. Pressure is achieved by stopping and starting the motor via a pressure sensor (also called a transducer); in more advanced units, this is done by digital control in which the speed of the motor varies with the demand and the difference from the pressure set-point, resulting in a very good pressure control. Some direct drive piston pumps are driven by a gasoline engine with pressure control via an electric clutch. In electric diaphragm pumps, the motor drives a hydraulic piston pump that transmits the oil displaced by the piston, to move the diaphragm.
Hydraulic and air-powered airless pumps have linear motors that require a hydraulic pump or an air compressor, which can be electric or gasoline powered, although an air compressor is usually diesel powered for mobile use or electric for fixed installations. Some airless units have the hydraulic pump and its motor, built onto the same chassis as the paint pump.
Hydraulic or air powered airless provide a more uniform pressure control since the paint piston moves at a constant speed except when it changes direction. In most direct drive piston pumps, the piston is crankshaft driven in which the piston will be constantly changing speed. The linear motors of hydraulic or compressed air drive pumps, are more efficient in converting engine power to material power, than crankshaft driven units.
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