Abstract: A machine for forming an inverted U-shaped folded fin with an aspect ratio of H/W includes a stationary frame, a locating device, a folding tool carrier and successive first, second and third folding tools. The carrier is horizontally and reciprocally mounted on the frame. The three folding tools are drivably carried by the carrier, each tool with a width substantially equal to W including an upper clamping block and a lower clamping block respectively for fixing a metal strip during formation of the heat dissipating fin. The first and second tools and the second and third tools are respectively spaced from each other at a distance substantially equal to H when the machine is at an original position. The locating device is also drivably mounted on the frame for fixing the horizontal metal strip relative to the frame when the three folding tools do not clamp the strip.