Assembly - December 2008 - (Page 50) Dispensing other parts against vibration and shock. These properties make RTVs an ideal choice for protecting sensors, displays and other electronics from humid or corrosive atmospheres. Formed-in-place gaskets are another application for RTVs. Such gaskets can seal liquids inside an assembly, or keep liquids and dust out. Electrically conductive RTVs can also prevent galvanic corrosion and act as a shield against electromagnetic interference. Because they’re dispensed as a liquid, RTVs can be used to create intricate gasket paths. Because of their thermal and chemical stability, RTVs are used in numerous applications in cars, trucks, recreational vehicles and even golf carts. They are used as gaskets for oil, coolant and air. Silicones are also used for potting and encapsulating electronic components, such as air bag sensors and wire connectors. In the aerospace industry, RTVs seal and encapsulate critical electronics. Because of their ability to dampen vibration and endure temperature extremes, silicones are used to seal cockpit instruments, cargo doors, windows and ventilation ducts. Silicone engine gaskets and wire seals stand up to continual buffeting from turbulent air currents. No consumer vehicle will ever see the rugged use and hostile environments that military equipment experiences, so it’s no surprise that assemblers of everything from tanks to naval cranes rely on silicones for gasketing, sealing, potting and encapsulating. If it can be done by a person, a robot can do it better, faster and more precisely. Manufacturers of heavy equipment, such as tractors, use silicones for the same reasons. Indeed, it’s not unusual for today’s tractors to be equipped with navigation systems and mini computers. RTVs keep these electronics working despite vibration, shock, heat and dust. Dispensing RTVs Although a wealth of RTV formulations is available, there hasn’t been a lot of options for applying them, at least until recently. Historically, RTVs were applied manually, and many assemblers continue to do this. Some have also moved to handheld semiautomatic dispensers that are aided by a pump. This is almost a requirement for dispensing extremely thick RTV formulations. While there is nothing wrong with manual dispensing, it is labor-intensive. 50 ASSEMBLY / December 2008 www.assemblymag.com http://www.beckwoodpress.com http://www.beckwoodpress.com http://www.beckwoodpress.com http://www.assemblymag.com
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