The object of this research is use different type of PET fold yam, with the heat shrinkage testing, simulate condition of tension changed in plant. In the stationary simulation condition at the 70-80°C in the fold yam, we get the tension maintain constant or abate, exceed 90°C of fold yam apace shrinking accrue biggest tension. But in the dynamic simulation condition at the 120°C, the shrinking to poise, exceed 240°C of fold yarn have melt and tension down.
