1. Tension control for feeding device: when machine stop, the film roll will not loose the film, the tension controller will tight the film to avoid film loose. • 2. Air blower device instead of bamboo: the feeding device adopt air blower device instead of bamboo. When machine working, the air blower will blow the air, to keep the film roll in the same position, to avoid the film to run up and down. • 3. The copper knife structure advantage: it adopts separate structing to avoid knife deform. It will grantee the bag quality. • 4. Rectification device and dancing roller: when machine is working, rectification device and dancing roller can avoid the previous bags heat sealing line to paste with second bag heat sealing line. The first bag move forward, and second bag move backward. • 5. Application of variable speed of main motor: when one film roll has different thickness, the gearbox can adopt two kinds of work way: a) the machine will change speed according to film thickness; b) fix speed to work with standard film thickness (10-20micron). Application of plastic bag production line: -hdpe: t-shirt bags, garbage bags, furniture cover films, laundry bags, shopping bags, take away bags -ldpe: agriculture films, construction covers, dust covers, furniture covers, pillow/mattress bags.