TDC unit is one of the two universal flange making systems in the world. It can save time and material drastically with its wel-seal, strong and durable joint structure. So it is especially suitable for producing duct with large section area. Today many famous buildings in the world utilize this kind of structure in the ventilation system such as the American Kennedy Space Center, Guangzhou CITIC Plaza etc. The unit consists of a feeding frame, main forming machine and a shearing unit, which includes grinder and hydraulic shearing unit. The hydraulic shearing unit makes fixed cutting available with very little burr, and may be operated automatically with a maximum work speed of 6 m/min. It is divided into four types: T-20, T-30, T-35, and T-40 with their corresponding duct corner T-20DC, T-30DC, T-35DC and T-40DC.