GFT Gelbo Flex tester

Introduction of Gelbo Flex Tester

The Gelbo Flex tester is a specialized instrument designed to evaluate the flex durability and mechanical integrity of flexible materials such as barrier films, laminates, and coated fabrics. By simulating real-world twisting and compressive deformation, this tester provides critical insights into the resistance of packaging and coated materials to pinhole formation, cracking, i barrier property degradation. Standards such as ASTM F392 i ISO 7854 define the testing methods that ensure accuracy, repeatability, and international comparability.

The Gelbo Flex tester, sometimes referred to as a rumple flex tester ili flex tester, operates by subjecting test specimens to simultaneous twisting and compressing motions. This combined action reproduces the mechanical stress flexible packaging materials experience during filling, sealing, transportation, and storage.

The test method, commonly known as the Gelbo test method, evaluates a material’s ability to maintain integrity under cyclic deformation. Materials that fail this test often develop microscopic pinholes or cracks that compromise the package’s barrier performance against oxygen, moisture, or gas transmission.

https://www.youtube.com/watch?v=HDpqg4jkaeA

Principle of the Gelbo Flex and Related Standards

Two primary international standards govern flex durability evaluation: ASTM F392 i ISO 7854.

ASTM F392, pod naslovom Standardna praksa za kondicioniranje fleksibilnih barijernih materijala za izdržljivost savitljivosti, specifies test conditions for assessing the resistance of flexible packaging materials to flex-induced pinholes and barrier failures. In this method, specimens undergo repeated flexing at 45 cycles per minute, involving a 440° twist combined with a 65 mm horizontal motion. The test is conducted under standard conditions of 23 ± 2°C i 50 ± 5% relative humidity. Depending on the desired conditioning level, test cycles may range from 20 to 2700, corresponding to levels A through E.

ISO 7854, Rubber- or plastics-coated fabrics — Determination of resistance to damage by flexing, defines three methods of flex testing. Method C, known as the crumple/flex method, closely resembles the Gelbo principle. Here, a cylindrical specimen is subjected to oscillating twist and axial compression, simulating real-life flex stress for coated fabrics, medical materials, and technical textiles.

Together, these standards establish the Gelbo flex procedure as the global benchmark for flex durability testing.

How the Gelbo Flex Tester Works

The Gelbo Flex tester (for example, the GFT Flex Durability Tester od Stanični instrumenti) operates with high precision to replicate ASTM and ISO flexing motions.

1. Priprema uzorka: Standard samples are 200 × 280 mm, cut in both machine and transverse directions.
2. Mounting: Samples are clamped or adhered to the tester’s mandrels, forming a cylindrical shape for simultaneous twisting and compression.
3. Flexing Cycle: The tester executes a 440° twist during the first 90 mm of stroke, followed by a 65 mm linear compression, at a consistent 45 cycles per minute.
4. Mode Selection: Users can select from five programmable test modes (A–E) to suit different material types or test objectives.
5. Result Evaluation: After conditioning, specimens are inspected for pinholes, cracks, or barrier degradation using OTR (Oxygen Transmission Rate), WVTR (Water Vapor Transmission Rate), or GTR tests.

This controlled process allows laboratories and quality control teams to quantify a material’s flex resistance and predict its performance under real-world mechanical stress.

Key Features and Main Parameter

The GFT Gelbo Flex tester series from Stanični instrumenti offers advanced technology designed for high precision and ease of use:

1. PLC Control & Touchscreen Interface – Ensures accurate motion control, user-friendly operation, and data repeatability.
2. Multiple Test Stations – Available with three or four stations for parallel testing and comparative analysis.
3. Programmable Test Conditions – Supports ASTM F392 modes A–E for versatile testing from quick screening (20 cycles) to endurance evaluation (2700 cycles).
4. Durable Mechanical Design – Engineered for long-term stability and compliance with ASTM F392 i ISO 7854 standardima.
5. Enhanced Data Reliability – Supports post-test evaluation of barrier integrity, pinhole formation, and mechanical strength changes.

GFT Gelbo Flex Durability Tester
Parametar	GFT-02 Model	GFT-01 Model
Kut savijanja	440° (90 mm) ili 400° (80 mm)
Kapacitet	3.5 N.m	2,5 Nm
Horizontalni potez	155 mm ili 80 mm
Stanice	3	4
Veličina uzorka	280 mm x 200 mm
Vlast	110~220V

Applications of Gelbo Flex Testing

Gelbo flex testing is essential in industries where flexible materials must retain barrier integrity and aesthetic quality after repeated handling or mechanical stress. Key application areas include:

• Flexible Packaging for food, pharmaceuticals, and medical devices
• Coated Fabrics and Films for industrial, textile, and outdoor uses
• Adhesive Laminates i composite structures
• Kontrola kvalitete in R&D laboratories i certification agencies

By identifying weak points early, manufacturers can improve material formulation, coating technology, and lamination processes.

FAQ

P: Po čemu se uređaj za ispitivanje izdržljivosti savitljivosti izdvaja od druge opreme za ispitivanje savitljivosti na tržištu?

O: Gelbo Flex tester tvrtke Cell Instruments može se pohvaliti jedinstvenom mješavinom preciznog inženjeringa i inovativnih značajki dizajna. Od njegovog intuitivnog korisničkog sučelja do njegovih naprednih mogućnosti automatizacije, svaki aspekt je pomno izrađen za optimizaciju performansi i korisničkog iskustva. Dodatno, njegova kompatibilnost u širokom rasponu materijala i industrija izdvaja ga kao svestrano rješenje za potrebe ispitivanja savitljivosti.

P: Kako tester doprinosi poboljšanju kvalitete i pouzdanosti proizvoda?

O: Podvrgavajući materijale rigoroznom ispitivanju savitljivosti, uređaj za ispitivanje izdržljivosti na savijanje pomaže identificirati slabosti i potencijalne točke kvara rano u procesu razvoja. Ovaj proaktivni pristup omogućuje proizvođačima rješavanje problema prije nego što oni eskaliraju, što rezultira proizvodima koji su otporniji, pouzdaniji i naposljetku više kvalitete.

P: Može li uređaj za ispitivanje izdržljivosti savitljivosti primiti različite veličine i oblike uzoraka?

O: Apsolutno! Gelbo Flex Tester dizajniran je za prilagodbu širokom rasponu veličina i oblika uzoraka, nudeći fleksibilnost i svestranost u testiranju. Bilo da radite s malim, osjetljivim filmovima ili većim, glomaznijim materijalima, naš tester može se prilagoditi kako bi s lakoćom ispunio vaše specifične zahtjeve testiranja.

P: Kako tester osigurava točne i ponovljive rezultate testa?

O: Preciznost je najvažnija kod uređaja za ispitivanje izdržljivosti savitljivosti. Preciznom kalibracijom i robusnom konstrukcijom osiguravamo da svaki test daje dosljedne, pouzdane rezultate. Osim toga, naš tester dizajniran je za smanjenje vanjskih čimbenika koji bi mogli utjecati na rezultate testa, dodatno povećavajući točnost i ponovljivost.

P: Koja je razina tehničke podrške dostupna korisnicima Gelbo Flex Testera?

O: U Cell Instrumentsu prioritet nam je zadovoljstvo i podrška korisnika. Naš posvećeni tim za tehničku podršku dostupan je za pomoć korisnicima sa svim pitanjima, nedoumicama ili tehničkim izazovima s kojima se mogu susresti. Bilo da vam je potrebna pomoć pri postavljanju, kalibraciji ili rješavanju problema, naši stručnjaci su tu da vam pruže brzu i učinkovitu podršku kako bi vaši procesi testiranja tekli glatko

Referenca

ASTM F392 Standardna praksa za kondicioniranje fleksibilnih barijernih materijala za izdržljivost savitljivosti