Spraying blisters and the stretch-blow forming are procedures from the finishing technique for the economic production of directly ready for use hollow bodies, with a precise muzzle, sealing range and equal to lasting wall thickness.
In the comparison to extruding blisters knew these hollow bodies no seams (squeezing edges) and so also pressures withstand, which develop for example when filling with char-acid beverages.
With spraying blisters (classifying procedures) first by injection moulding a cylindrical Preform (preform) with the later muzzle and sealing range is made of a thermoplastic. This Preform is adjusted in a conditioning station thermally to the blowing profile and supplied afterwards to the blowing procedure. During the blowing procedure only the Preform is brought in the ranges which can be expanded above the softening temperature and blown up by means of blowing thorn and blow tool on the final outline. After the cooling now the finished shaped part can be released from form.
With the stretch-blow forming (two-stage procedure) the Preformen is brought in an IR heating module with 8 heating zones on transformation temperature, whereby the individual zones can be steered separately around the suitable heating profile for the blowing process to receive. After the Preformen a balance zone these to the blowing station will hand over. In the blowing station the Preformen is stretched at the same time by means of straining thorn in longitudinal direction and with a small blow pressure (5-15 bar) in circumferential direction, so that the molecule chains can orient and then with high pressure (- 40 bar) finished blown out. The biaxiale orientation of the molecule chains has the advantages that a higher firmness with smaller wall thickness (permeation reduction) and a better surface gloss arise.
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