PETpla.net Insider 09 / 2010

Vol.6 PET planet print PREFORM PRODUCTION 26 PET planet insider Vol. 11 No. 09/10 www.petpla.net The Rapid Guide to Perfect Preforms by Rick Unterlander and Ottmar Brandau Troubleshooting guides have suffered in the past from being locked away in offices and not being available to the people that actually need them. Considering the high cost of machine and tools high scrap rates can be a costly proposition eating away at already tight margins. PETplanet’s “Rapid Guide to Perfect Preforms” takes a different approach. Bound in laminated paper that is easy to clean off, the small format of the book of 108mm by 151mm (4.25” by 6”) allows easy storage in back pockets or tool boxes. It has been written for the people on the floor of injection moulding companies to support their daily work in making the best preforms possible. The product of two industry experts, Rick Unterlander and Ottmar Brandau, it gives concrete advice on 35 of the most common problems in preform manufacture, most illustrated by pictures. From high AA levels to wavy bodies processors can find help when they need it. Read chapter 14 of the story... PET planet print vol.6 The Rapid Guide to Perfect Preforms machine no./name 14. Internal Gate Sink Symptom: An internal surface depression directly below the gate nub. Cause: The gate area has been deformed while it was still hot. Solutions: 1. Check water cooling temperature. This should be 7 – 10ºC (45 – 50ºF) for optimum cooling. 2. Check water cooling flow to mould and robot receptacles. This should be at the mould manufacturers rating (for a given preform size and cavitation). 3. Check that the preform fit into the robot receptacles is not too restrictive to cause gate deformation while being drawn into the tube. 4. Check that no anomalies are present on the robot cooling receptacles. Repair if necessary. 5. Ensure the mould / robot alignment is accurate. 6. Check nozzle tip heat settings. This area has a major impact on internal gate sink. Settings too high may cause the gate area to remain hot. The settings should be reduced as necessary to minimize the risk of overheating yet not too low to cause crystallinity to form. 7. Check all temperature readings and adjust as necessary. PET resin should be melted at about 280ºC (536º F) +/- 10ºC (18ºF). Decrease as necessary.