PETpla.net Insider 04 / 2010

PREFORM PRODUCTION 17 PET planet insider Vol. 11 No. 04/10 www.petpla.net 4. Check that transition position is set to about 13% of shot- size + cushion. Lower values may result in overfilling. 5. Ensure clamp tonnage is adequate for the preform size, cavitation, and process. Typical values are about 0.28 - 0.56t/cm 2 (2 - 4t/in2) of projected preform area. 6. Check that there is no debris on the mould mating surfaces. These surfaces should be kept clean at all times. 7. Check to ensure that the mould neck inserts are properly aligned and seated. 8. Check all temperature readings and correct if necessary. PET resin should be melted at about 280ºC (536ºF) +/- 10ºC (18ºF). 9. Check that all thermocouples are properly inserted and contacting the bottom of the wells. 10. Check extruder back pressure and minimize if possible. Back pressure should be sufficient to provide good melt mixing, but not too little to cause bubbles to appear. Typi- cal range is 15 – 20 bar (200 – 300 psi). 11. Check screw rpm and minimize if possible. Screw speed should be reduced as much as possible to minimize shear heating, yet still recover within the cycle time of the machine. The stopped time at the end of recovery should be about 2sec to offset any fluctuations during screw recovery. 12. Check hardware for worn, damaged or failed components, specifically the mould neck inserts, cavity tapers, and lock ring tapers. name ................................................................................................................ company ........................................................................................................... function ............................................................................................................. street................................................................................................................. city ................................................................................................................... country .............................................................................................................. phone ............................................................................................................... fax.................................................................................................................... e-mail................................................................................................................ credit card ......................................................................................................... expiration date.................................................................................................... name on card ..................................................................................................... PETplanet print Vol. 6: The Rapid Guide to Perfect Preforms by Rick Unterlander and Ottmar Brandau prices in EUR + VAT. fax: +49 (0) 6221-65108-28 info@hbmedia.net www.petpla.net Order your copy now! 1- 3 exemplar each 129,- € 4 - 10 exemplar each 99,- € > 10 exemplar each 69,- € Table of Contents i..................................... About the Authors ii............................................. Introduction chapter 1.......................................... AA Level High 2..................................... Accordion Preform 3....................................Air hooks / Streaks 4............................................ Black Specks 5................................................... Bubbles 6.............................................. Burn Marks 7..........................Colour Streaking / Peeling 8.............................................. Crystallinity 9............................................. Drool Marks 10.......................................................Flash 11......................................Gate Depressions 12............................................ Gate Peeling 13.............................. Gate Voids / Pin Holes 14......................................Internal Gate Sink 15............................................ Internal Sinks 16.....................................................IV Loss 17........................................ Long Gate Nub 18........................................... Milky Preform 19.........................................Moisture Marks 20............................ Neck Finish out of Round 21....................................Parting Line Crease 22............................. Parting Line Deformation 23......................................Preform Yellowing 24...............................................Short Shots 25.......................................................Sinks 26......................................................Splay 27........................................Stretched Necks 28..................................................Stringing 29......................................Surface Blemishes 30......................................Thread Flow Lines 31.....................TSS (Top Sealing Surface) Sink 32................................................... Unmelts 33............................. Wall Thickness Variation 34..............................................Wavy Body 35...............................................Weld Lines