The stretching production of PVC film is carried out on the rolling machine production line or specialized stretching machines. The stretching methods include unidirectional stretching and biaxial stretching. Unidirectional stretching refers to stretching the longitudinal or transverse direction of the membrane blank, while biaxial stretching refers to stretching both the longitudinal and transverse directions of the membrane.

　　Unidirectional stretched PVC film is currently widely used in rolling machine production lines. The method is to strip the PVC film blank formed on the roller of the rolling machine from the surface of the roller and introduce it into the stretching machine (at this time, the temperature of the film blank is above the glass transition temperature and below the melting temperature). The two ends of the film blank are clamped up and down by a smooth running conveyor belt. As the horizontal running distance of the conveyor belt at both ends of the film blank gradually increases, the clamped film blank is horizontally widened by the conveyor belt. After cooling and shaping, it is rolled up. This method of producing film blanks using rollers with smaller working face sizes and then stretching them to produce wide width films is both economical and convenient.

　　There are polypropylene film, high-density polyethylene film, and polyvinyl chloride film that can be used for unidirectional stretching. Bidirectional picking and stretching of thin films are generally carried out on specialized stretching machines. The stretched membrane blank is first introduced into the longitudinal picking and stretching roller composed of multiple rollers. The roller body is heated by steam, and the PVC transparent film is pulled forward by the roller.