duct board cutting machine manufacturers SBKJ GROUP (SBKJ INC.)is based in the Yangtze River Delta, near Shanghai, China. Our company is a national new high-tech enterprise which is specialized in the development and manufacture of machines, such as tube forming machines, plasma cutting machines, for the production of round ducting and fittings in sheet metal, mainly for the climate and ventilation industry. website:http://www.spiraltubeformer.com/