MIT Folding Endurance Tester for Paper

What is the MIT Folding Endurance Tester for Paper?

An MIT folding endurance tester repeatedly folds a paper strip under tension through a fixed angle until it breaks, counting the double folds. It assesses resistance to repeated flexing in banknote, security, map and creased products.

Overview

A strip of defined width is clamped under a set tension and folded backwards and forwards through a defined angle, usually about 135 degrees each way, at a controlled number of double folds per minute. The fold line forms against a narrow roller or a clamp edge, and the instrument counts folds until the specimen breaks or a preset maximum is reached. The applied tension is selected from a set of weights according to the grade, while the folding head geometry and rate are fixed by the standard. Because the result is very sensitive to the fold edge condition and to the exact tension, these elements must be inspected regularly, and humid or low-temperature conditions are sometimes used for banknote and security papers.

How does it work?

Mechanical paper tests apply a controlled force or deformation to a conditioned specimen and record the load or the extent of damage. Tensile testing pulls a strip at constant rate and records breaking force, elongation and tensile energy absorption, from which indices are calculated using basis weight. Tearing resistance is measured by the energy absorbed when a specimen with a pre-cut slit is torn by a pendulum or a falling weight. Folding endurance counts the number of double folds a strip withstands under tension before it breaks. Surface and absorbency tests use different principles: water absorbency is determined by the mass of water taken up by a defined area during a timed contact, smoothness by the air flow between a measuring ring and the sheet surface, and porosity by the air flow through the sheet itself at a defined pressure difference.

What are the key features?

• Fixed folding angle of about 135 degrees each way
• Selectable tension weights for different grades
• Automatic fold counting to break
• Preset maximum fold limit for tough papers
• Folding head and roller inspection access
• Optional humidity or low-temperature enclosure

What are the technical specifications?

A typical mit folding endurance tester for paper configuration offers folding angle of About ±135°, folding rate of 175 double folds per minute typical, tension weights of 0.5 / 1.0 / 1.5 kg options, specimen width of 15 mm standard, counter range of 0–99999 double folds and fold head radius of Per ISO 5626 or TAPPI T511. Values are indicative of the product class; the exact figures for each configuration are confirmed on the quotation and the calibration documents supplied with the instrument.

Which applications is it used for?

The MIT Folding Endurance Tester for Paper is used in banknote and security paper endurance testing, map, tracing and document paper assessment, creased carton board folding behaviour and coated paper flexing resistance. Across the wider Paper Quality Analysis class, laboratories also deploy it for tensile strength and elongation of packaging papers, tearing resistance of sack, tissue and bound papers and water absorbency of sizing and coating grades.

Which standards and certifications apply?

Relevant standards and methods include ISO 1924-2, ISO 1974, ISO 535, ISO 8791-2, ISO 5626, ASTM D828, TAPPI T494, TAPPI T414, TAPPI T441 and IEC 61010-1. Certification candidates for this model are CE and ISO 9001 manufacturing; each is to be confirmed for the specific configuration before shipment, and certificates are supplied only where they have been issued.

Condition specimens to the standard atmosphere, usually 23 °C and 50% relative humidity, before every mechanical test, because strength properties change sharply with moisture. Cut specimens with sharp dies or blades and reject those with damaged edges, since a nick initiates premature failure. Keep grips clean and aligned, and verify load cells with certified masses or a reference load cell at defined intervals. For absorbency and surface tests, control the water temperature, contact time and pressure difference, and clean measuring rings and plates, because deposits change the flow. Record basis weight, test direction, specimen count and conditioning with every result so that indices can be recalculated.

How do I select the right MIT Folding Endurance Tester for Paper?

Specify a folding endurance tester when the product is repeatedly handled, folded or flexed, and confirm the folding angle, rate and tension range match the standard you follow. Check the fold head and roller for wear at each service, since a sharp edge or a flat spot changes the count noticeably, and consider a conditioning enclosure for security papers.

How does it compare with other Paper Quality Analysis variants?

Select the test that corresponds to the specification you must meet and to the failure mode you are investigating. Tensile testing is fundamental for packaging, bag and label papers because it defines strength in the principal load direction. Tearing resistance is important for papers that are handled, punched or bound, and for tissue and sack grades. Internal bond, folding endurance and tensile energy absorption matter for papers that are creased or repeatedly flexed. Water absorbency is specified for papers that are glued, coated or used outdoors, while smoothness and porosity are specified where print quality and ink penetration matter. Each instrument should be capable of the exact conditions named in the standard, since test length, strain rate and contact area change results appreciably.