Sink roll cut is continuous hot galvanized coil production when a product surface defects, it not only directly affect the appearance of hot dip galvanized products, but also affect the use of hot dip galvanized products performance, it can also lower the corrosion resistance of hot dip galvanized products, make the product is in use or transport, corrosion in scratch place first, lost the characteristics of hot dip galvanized products should have;In addition, there are hot galvanized steel sheet can't sink roll cut as caitu substrate, anyhow sink roll cut for our hot galvanizing production enterprise is a great harm.So, we must be clear sink roll cut mechanism, so as to take the most effective measures to prevent and control the sink roll scratch defect.