EDI’s FastGap system, used by extrusion processors to change sheet or film thickness without stopping production, is now claimed to yield even more extruder uptime. Although the patented single-point adjustment mechanism in the standard FastGap system eliminates the need to reset the flexible-lip bolts or install an alternate lower lip with each change in product thickness, processors still have to shut down lines periodically to disassemble, clean, and lubricate the FastGap mechanism.

Now the new Toggle FastGap system, for which EDI has secured another US patent, is claimed to end even this downtime.

In standard FastGap equipment, the gap changing mechanism consists of a stationary and a moving bar with arrays of male and female keys, respectively, set at an angle to one another to slide against one another, under considerable pressure, during gap adjustment.

“The repeated metal-on-metal contact is what has made lubrication necessary,” explains John A Ulcej, EDI’s executive vp of engineering and technology. “To eliminate lubrication, we’ve replaced the old mechanism with an array of toggles along the width of the die. Instead of the sliding motion of the keys, there is the rotary motion of the pins and bushings at the ends of the toggle shafts. In addition, the toggles provide greater mechanical advantage in translating the adjusting torque applied by the operator into the bending force exerted upon the lower lip.”

He continues: “With adjustment of the lower lip only, the die opening can be varied over a range of 5.1mm. An additional 2.5mm is available with the top lip, which controls the transverse gauge profile. Together, these capabilities increase the range of gap adjustment from the previous maximum of 2.5mm to 7.6mm.”

The ability to make substantial changes in product thickness without stopping production is a major advantage for custom processors and other manufacturers who carry out frequent product change-overs. Companies running film and thin sheet are also said to benefit because the FastGap system permits purging to be carried out quickly, without having to stop the line. Special FastGap systems with reduced ranges of gap settings are available for producers of thin film.

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