GFT Gelbo Flex Durability Tester
GFT Gelbo Flex Durability Tester

Vinatoru Enterprises GFT Gelbo Flex Durability Tester

The Gelbo Flex Durability Tester GFT392 is designed for Flexible Barrier Materials and complies with ASTM test method F392. Available in 120 VAC or 220 VAC.

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This instrument has been designed to determine the flex resistance of flexible barrier materials by applying repetitive strain. Pinholes formations are the criteria for measuring failure and are determined by use of colored turpentine and allowing it to stain through the pinholes onto a white backing. Specimens of flexible materials are flexed at standard atmospheric condition (23°C / 73°F and 50% relative humidity). The flexing action consists of a twisting motion combined with a horizontal motion, thus, repeatedly twisting and crushing the film. The frequency is at a rate of 45 cycles per minute. There are 5 test conditions to choose from. One may choose a test cycle that simulates real conditions from partial flex and 20 cycles to full flex for 2700 cycles.

  • Condition A – Full flex for 1 hour (2,700 cycles)
  • Condition B – Full flex for 20 minutes (900 cycles)
  • Condition C – Full flex for 6 minutes (270 cycles)
  • Condition D – Full flex for 20 cycles
  • Condition E – Partial flex only for 20 cycles
  • An additional operator defined cycle has been added – maximum number of cycles is 10,000.


  • Flexible plastic films
  • Coextruded structures
  • Coated films and paper


  • Shows a visual result of pinholing and delamination
  • Maximum stroke (distance traveled by moveable mandrel): 6” (155 mm)
  • Twist: 440° on long stroke (6” or 155 mm) and 400° on short stroke (3.25” or 80 mm)
  • Total counter for cycles
  • Frequency rate: 45 cycles per minute
  • Stainless steel cutting template 11 ”x8” (280 x 200 mm)
  • User selectable test condition switch
  • Ballspline assembly provides a smooth and repetitive motion
  • High level of safety – safety interlock, safety guard, emergency stop
  • Stainless steel and anodized aluminum construction
  • Dimensions: 40”Lx12”Wx12”H (1015x305x305 mm)
  • Instrument weight: 100 pounds (46 kg)
  • Required utilities: 120 VAC @ 60Hz or 220 VAC @ 50Hz, depending on model


  • Stainless Steel Template (200mm x 280 mm)
  • 5/16″ Nut driver
  • 1242 Heavy-Duty Lithium-Polymer Grease
  • Film Sample
  • Trimming Knife w/ 5 replacement blades
  • Large Cutting Mat (12″ x 18″)

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