One of the standard equipments used for this determination is the Martindale Abrasion Tester. This apparatus gives a controlled amount of abrasion between fabric surfaces at comparatively low pressures in continuously changing direction. Circular specimens of fabric are abraded under known pressures under a motion which is the resultant of two simple harmonic motions which are at right angle to each other. The resistance to abrasion is estimated by visual appearance of by finding the loss in mass of the specimens.
The Martindale Abrasion Tester consists of a plate which is given a motion combining two harmonic motions at right angle through three rotating eccentric pegs, four number specimen holders for mounting the fabric under test one and four number abradant holders against which the test specimens are abraded.
The plate is supported on three self lubricating nylon discs and has three slots for locating the eccentric pegs in. The pegs are rotated with the help of an electric motor, worm reduction gear box and sprockets and chain arrangements such that the central peg is rotating at a slower speed than the two outer pegs which rotate at the same speed. The movement of the pegs causes the plate to move in two mutually perpendicular directions in simple harmonic motions, thus providing the necessary abrading action.
The test specimens are mounted on flat metallic discs and are backed with a thin layer of polyurethane foam. The shafts of the specimen holders are guided vertically in bushes on the moving plate. Thus the movement of the plate causes the specimen holders to move with the plate, thereby abrading it against the abradant fixed below the specimen holders. The force on the test specimens can be altered by adding or removing dead weights from the specimen holders. The abradant fabrics are mounted on four abradant holders fixed on the base of the equipment.
A preset counter which counts the number of rotation of outer pegs and stops the motor automatically after a preset numbers of rotations is provided with the equipment. Template for marking the test specimens and abradants, disc weights to keep them flat during fixing and mounting jig for test specimens are also provided as standard accessories.
The various components are mounted on a sturdy fabricated steel base and are finished in dark grey hammer tone painting and bright chrome/zinc plating to give them a corrosion resistant finish.
|Max.number of test specimens which can be tested at a time||Four|
|Speed of outer pegs||47.5 +/- 2.5 r.p.m.|
|Ratio of speeds of outer pegs to centre peg||32/30|
|Linear movement of pegs||60.5 mm|
|Working area of specimen holder||6.45 cm2|
|Pressure on test specimens||3, 6, 9 & 12 KN/m2|