Patent ID: 6203716
Filing Date: 2001-03-20
Classification: C23F

Abstract:
A method of chemical milling which includes the following steps:(a) suspending an extrusion or casting having an external surface area substantially in excess of an internal surface area wherein the extrusion or casting is formed from metal having a peripheral wall defining an elongate open ended hollow body which has an array of fins extending outwardly from the peripheral wall in an etching solution wherein initially the extrusion or casting is fully submerged in the etching solution by virtue of its weight and which thereafter is rendered buoyant by metal being removed from the extrusion or casting by the etching solution wherein the casting or extrusion is supported by a non-buoyant support which maintains the casting or extrusion in a fully submerged condition throughout the immersion in the etching solution with said hollow body and said fins oriented in a substantially vertical orientation; and(b) withdrawing the extrusion or casting from the etching solution when required.