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Chemical removal, also called deep etching, is an electroless (chemical) etching process for the production of complicated components. In contrast to electroforming, individual areas of a workpiece are uniformly dissolved in an immersion bath by the action of a liquid etchant. Surfaces not to be machined are protected by covering (masking). The process is used above all when large surfaces have to be removed, the wall thickness of very thin-walled components is to be further reduced in individual areas or no thermal stress on the component is permissible (e.g. during mechanical processing).
In aviation, components made of aluminium and titanium alloys in particular, but also the nickel material, are optimised in terms of geometry and weight by chemical ablation. Examples are flight tribrach and compression housings made of titanium and turbine housings made of nickel material.
The process is widely used in the manufacture of leadframes. These very thin strips of a copper alloy (these are mostly precipitation alloys) are etched after a mask. The distances between the webs are less than 1mm and leadframes can be etched which could not be punched mechanically. In order to judge whether a lead frame has been etched or punched, a glance under a microscope is sufficient. Etched leadframes have a clean edge, while punched leadframes have a slight burr caused by breaking out the material.