Aipex Engineering: Blown Film Thickness & Width Control System
The SIG140 BW can be retrofitted to any blown film line and combines a fast acting bubble width control system with the conventional thickness control system. The width control sensors are ultrasonic and situated 120? apart on a hexagonal ring around the bubble, usually positioned just above the freeze line. The SIG140 calculates the signals to a single lay-flat width measurement. The control system compares the width signal against target and inflates or deflates the bubble to achieve correct width. The SIG140 also has a reportedly unique feature — an eccentricity measurement showing any displacement of the bubble and its direction relative to the die-bolts on the die. This enables the operator on start-up to adjust the die-bolts to give a concentric bubble with the most uniform thickness profile.