Many models can be made to forgotten the method, by squeezing the sheet metal. Extortion is used for any thin-walled parts (e.g. fairings, cowlings, shrouds, wings, wheels, and similar). Often they are made of brass or aluminum alloys. The material is pre-annealed with a pair of scissors and cut the workpiece with considerable allowances. The tools serve as a mandrel, anvil and various hammers. The process of knockout s is the stretching of the material when its thickness decreases, and in the sediment, which implies an increase of the thickness.
The first process used in those places where to make the bulge metal; sediment is produced most often around the edges. To this end, the perimeter of the workpiece is collected in uniform folds, and then hammer the corrugations aligned, starting from the center to the periphery. To avoid clinching, used rubber, aluminum or wood hammers. As a result of multiple repetition of this operation, the material “sets”, that is, increasing its thickness.