A line of weakening (24) formed of spaced bridges (44) separated by slits (42) is formed in the skirt of a temperevident closure after the closure has been moulded. The line of weakening (24) is formed by a cutting operation using a knife blade (32) along the edge of which the closure is rolled...http://www.google.es/patents/US5809860?utm_source=gb-gplus-sharePatente US5809860 - Methods for forming lines of weakening in closures
Methods for forming lines of weakening in closures
