Die and calibration equipment

The draw-down (achieved by the haul-off and sizing rings) brings the 

22 Illustration of melt swell in short and long die lands. The swell Is counteracted by tension from the pull rolls (after Richardson). 

1 The removal of dirt particles, etc. is particular important in pipe extrusion pipe lifetimes under pressure are increased when particular care is taken to purify the polymer. 

24 Calibrator with ultrasonic gauging for pipe and tubing extrusion A=rubber seals B = stainless steel guides C brushes (to remove bubbles) D ultrasonic probes E water drain and water inlet. 

25 On the left a profile opened from the die shown on the right. The hot liquid profile, as it leaves the die, has dimensions which mceed those of the die tension and calibration equipment bring it, when cooled, to a size in which the dimensions are below those of the die as indicated, 12% in this case (after General Electric Pla ics). 

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