The new Tandem external gauge control (TEGC) system from Addex, Stoughton, Mass., combines gauge control by the company’s EGC air ring with a bubble-stabilizing lower air ring. The configuration is said to boost output by 15% to 30% compared with Addex’s standard EGC system. The standard automatic system is said to reduce film thickness variations by up to 70%, typically resulting in a 5% to 6% raw material savings.
The lower single-lip air ring matches the die diameter. It is fed by a blower about half the size needed for a typical air ring. Air gently cools the bubble and stabilizes it. Air then is fed to the dual-lip automatic gauge-control air ring above the single-lip unit. The more stable bubble allows for higher output without jeopardizing gauge control.
The upper EGC air ring is 2 in. (50 mm) bigger than the die size. Therefore, a 16-in. (400-mm) die employs a 16-in. single-lip air ring and an 18-in. (450-mm) EGC air ring situated on top (photo).
Addex simplified the original EGC air ring by moving the electronic circuit board (the “brains”) from outside the ring into the plenum area. This enables the user to rely on its own control panel if desired. Users may also use their own thickness measuring system and connect it via Ethernet to the air ring.