Velcro fasteners, those little pads of fuzzy plastic hooks and eyes, have found low and high-tech uses in and out of this world.
In the clothing industry they are used instead of press-studs and zips. In medicine, they are used to attach the chambers in the Jarvik 7 artificial heart. In the space shuttle, astronauts use Velcro tape to stick trays, food packages, scientific equipment, and occasionally themselves, to some convenient surface to prevent them floating away in the weightless environment.
Swiss engineer Georges de Mestral conceived the idea that evolved into Velcro after a walk in the woods 1 day in 1948. He came back home with the burrs are stuck to his socks and to his dog and decided to investigate why burrs sticks so well to wool.
Under the microscope he saw how tiny hooks on the ends of the burrs caught in loops in the wool.
De Mestral soon devised a method of reproducing the hook and loop arrangement in woven nylon. He called the product Velcro, a contraction of velours and crochet, the French word for hook. The original patent on Velcro expired in 1978 and there are now many imitations, but Velcro remains a registered trade name.
Velcro is made by weaving nylon thread to produce a fabric containing densely packed with little loops. This forms the looped part. To form the hooked part, loops in a separate piece of fabric are cut, so that half of each loop becomes a hook. The fabric is heated to set the loops and hooks permanently in shape. It is then dyed, bonded to a suitable backing and cut to size.
Velcro is particularly long-lasting. It can usually be fastened and unfastened many thousands of times and may well outlast the product to which it is attached.
Velcro is designed to be peelable – to be opened by hand with comparatively little effort. However, it has very high shear strength – resistance to sideways forces. Some Velcro is so strong in chief shear strength that a piece less than 5in (120mm) square can support a load of one ton. This property has prompted experiments in using Velcro to make aircraft bodies. The aim is o replace rivets with Velcro strips, saving weight and making assembly simpler.
Picture Credit : Google