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.

"It is thought that the Japanese conceived such a grinder in 1985 and subsequently a paper stated that they have made an electrode of 5 microns (0.005 mm) in diameter, however no further evidence has emerged," added Marsh.

The University believes that the ability to produce such quality tiny holes in any conductive material represents a significant advance in mechanical engineering and will benefit designers in the medical and laboratory sciences.