The film blowing process is mostly characterized by the following three ratios. First,the blow-up ratio of the final bubble dimeter at the freezeline height to the die diameter.this ratio determines the magnitude of melt stretching in the transverse direction and normally takes values in the range form 1 to 5 .second, the take-up ratio,TUR,is expressed as a ratio between the film velocity above the freezeline height(nip velocity) and melt at the die exit. This ratio determines the magnitude of melt stretching in the axial machine direction which is usually kept between 5 and 40.thrid, thickness reduction, TR,is the ratio of the die gap to the final film thickness and is typically in the range of 20-200