Throughout history and all cultures, Moss Agate has been known as the crystal of gardeners and agriculture. It was considered a miraculous healing stone for tribal priests of the past, giving them power to interact with our human organic system, and was used as a talisman to make warriors strong and victorious.
FSW has been used to weld many softer materials (aluminum, copper, magnesium, etc.) for over a decade, and has more recently shown promise for welding harder metal alloys (steels, titanium, and nickel). Shown in Figure 4 is a typical friction stir weld made on Â¾-in. (19-mm) thick high-strength steel. Research is currently underway to evaluate tool life and weld properties for FSW of steel. EWI has been working to advance the friction welding processes for nearly 25 years.
It dissipates energy or power in various moving parts of machines & causes irreversibility in various processes. However, it is useful in various situations. Friction enables use to move on a surface or plane. Friction is very useful in self-locking devices. Example in screw jack friction is very useful to prevent overhauling of screw. Friction can prevent skidding of wheels on road. Friction slows down or brings a moving body to rest by dissipating its kinetic energy to heat energy.