In plastic sheet extrusion production, polymers are melted through a slot or flat die (extruded) to form a thin, molten sheet. This sheet is is attracted towards the surface of a chilled roller where it immediately solidifies. The sheet then passes through a series of rollers which will determine thickness and texture before being edge trimmed and cut to the required size (heavy gauge sheet) or wound onto a roller (thin gauge sheet). Extruded plastic sheets are often used for thermoforming into a final shape (for example in the manufacture of refrigerator or freezer internal panels or plastic beverage cups).
Detection of die "bolt heater" problems is necessary to ensure uniformity of the die temperature, control roller temperatures and to detect film breakages.
- Linescanner facilitates control of melt curtain temperature
- Temperature measurement using spot sensor for downstream sheet temperature measurement optimizes final product quality