The effect of cooling time on the shrinkage of blow-extruded articles
Polimery 2000, No 10, 713
SummaryProcessing shrinkage of the major air distribution channel used in Lublin II (Daewoo Motor Polska) delivery vans, made of medium density polyethylene (Solvay's Eltex RSB 714) by blowing extrusion, was studied in relation to cooling time in the mold (29–40 s) (Tables 1–3). Spacing of the channel openings used to mount the channel in the chassis, is essential as regards the dimensional correctness of the channel. The spacing of the extreme mounting openings is known as the channel length (L in Fig. 3). Channel length was measured immediately after the channel was removed from the mold, and re-measured in 8 hours and in 24 hours (Fig. 6). To keep to the required dimensional tolerance, the cooling time of 29 to 34 s is most advantageous; as the cooling time is protracted, the major upper dimension of the channel is exceeded and the resulting article is defective (Fig. 8).