The Flex Durability Tester simulates stress, which flexible packaging materials (such as coated or vapor-coated paper, plastic films and laminated material) may be subject during the automated packaging process. The KFT-C covers the determination of the flex resistance of flexible barrier materials with a high repeatability. After the test, any failure of the barrier can be determined by a gas permeability test (using our GDP-C tester) and/or by a water permeability test (using our WDDG tester). Physical holes through the material can be detected by the colored-turpentine-pinhole test.

The device uses a stationary and a movable mandrel of 90 mm diameter each. The specimen is affixed between the two mandrels in the shape of a cylinder. To do this, both ends of the specimen will be affixed with a locking onto each mandrel. In this initial position, the distance between the mandrels is approx. 180 mm (face to face). Two different motion cycles are described in the ASTM F 392-93 standard: One motion cycle uses a twisting angle of 400° and a horizontal move of 80 mm simultaneously (short stroke). The other motion cycle uses a twisting angle of 440° and a horizontal move of 90 mm simultaneously, followed by a single horizontal movement of 65 mm without twisting (long stroke). The frequency for both motion cycles is at a rate of approximately 45 cpm. 

A logic module interprets the information from 7 different contactless switching sensors and controls the valves for both pneumatic linear actuators. Using the selector switch, the 5 different standard testing conditions can be set. Additionally the operator can choose any desired numbers of cycles for both different types of motion cycles. The actual testing condition is shown in the LCD-display on the logic module. During a running test the current number of cycles is also indicated in this LCD-display.