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Researchers have fashioned a microwave drill using parts found in common kitchen appliances. According to a report published in the current issue of the journal Science, the drill can bore through tough substances such as concrete or glass without the usual whine or dust of its mechanical counterparts.
Radiation has long been used to forge holes; lasers are widely used to create tiny incisions. The new microwave-drill, however, combines the precision and cleanliness of a laser drill with the cost-effectiveness of a mechanical one. To manufacture the drill, Eli Jerby and his colleagues at Tel Aviv University focused the microwaves from a magnetron (similar to those found in conventional microwave ovens) using a metal box and a piece of cable. Then, with the help of a mirror, the team directed the radiation from the cable's other end at a spot just underneath the surface of the material being drilled. The microwaves increased the temperature of the substance, enabling better absorption of more microwaves, and created a molten hotspot. An electrode pushed through the hot spot served as the drill bit and produced the hole. The scientists successfully drilled holes ranging in diameter from one millimeter to one centimeter in ceramics, concrete, basalt, glass and silicon, and they conclude that "the method is applicable for drilling a variety of nonconductive materials." The technique fails on substances such as sapphire, whose melting temperature is greater than 2,000 degrees Celsius.
The microwave drill is not yet ready for mass production. One significant concern is radiation exposure for operators, although initial testing indicates that shielding will limit the level of exposure to accepted standards.
