World’s smallest hole?

University scientists have developed machinery so sophisticated that they can drill a hole narrower than a human hair.

The engineers at the Cardiff University’s Manufacturing Engineering Centre, are drilling holes as small as 22 microns (0.022 mm) in stainless steel and other materials. The human hair varies between 80 microns (0.08 mm) down to 50 microns (0.05 mm) in thickness.

The holes were ‘drilled’ at Cardiff using electro-discharge machining (EDM).

"Standard rods (used in EDM machines) available commercially are capable of making holes of 150 microns. Although lasers are able to make small holes, these are of poorer quality when compared to the EDM process. Lasers make holes that taper, whereas EDM makes parallel or vertical holes," said the Centre’s marketing director Frank Marsh.

The process is achieved by creating a minute electrode, with a diameter of only 6 microns (0.006 mm), which was itself produced by manufacturing a highly precise wire electrode discharge grinder.