Large-diameter roller drum (800) made with superior quality steel,the surface is treated either with grinding or milling so that the wear and tear of the fabrice is reduced to the minimum. Chassis and Deputy roller structure using high-quality carbon, welded together, sturdy and durable. The main and sub-roller roller speed differential design used effectively to increase the flatness of hot fabric. Direct thermal roller main and effective heating area of more than 90% and improve the utilization of energy. Using variable frequency in speed adjustment to achieve flexibility, asmoothniess and low noise level in speed adjusting.