General: The extruded fin is formed from an outer aluminum tube with a large wall thickness (muff), which is aligned over an inner base tube. This assembly is fed into the triple-spindle finning machine. Three sets of special cutting discs literally squeeze or extrude the aluminum fins up and out of the muff material in a spiral shape and give firm pressure contact with the base tube in a cold rotary extrusion process. Machine Specification: Output Shaft Speed: ( adjustable )