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Taber Multi-Finger Scratch Tester 710
Taber Multi-Finger Scratch Tester 710
Der TABER Multi-Finger Scratch / Mar Tester 710 dient zur Messung der relativen Widerstandsfähigkeit oder Anfälligkeit einer Materialoberfläche gegenüber Kratzern, Schrammen, Furchen, Kratzern, Gravuren und anderen ähnlichen physikalischen Schäden, die nicht als gewöhnlicher Verschleiß eingestuft werden. Das Gerät wird üblicherweise als Fünf-Finger-Prüfgerät (Fünf-Arm-Prüfgerät) bezeichnet und am häufigsten zur Bewertung von Kunststoffen verwendet.
The Multi-Finger Scratch / Mar Tester 710 has a pneumatically driven, movable platform on which the test sample is mounted. The platform moves linearly and is operated via a rotary knob for single or multiple tests. An electronic timer displays the speed, which can be controlled by reducing or increasing the air pressure.
A bridge carries five independent, toothed fingers that exert a constant, vertical load on interchangeable scraper tips. The gantry system has a handle for raising and lowering the arms. In addition, five supports are built in to allow one or more arms to be placed in an upright resting position so that the arm does not touch the specimen during the test.
Individual weights with different loads are attached to the top of each arm finger to exert a standard force on the surface of the test material. Each device contains a set of weights with 2N, 3N, 4N, 5N, 6N, 7N, 10N, 15N and 20N force. Optional weight sets are also available consisting of either 4N, 8N, 9N, 12N or 8N, 13N, 18N weights. In addition, an optional 25N weight or precision weight set is available to achieve 0.6N loads.
Although typically used to test flat specimens up to 22 mm thick, the 'free-floating' arms also allow you to test slightly contoured specimens, provided they are rigid or adequately supported. A spring-loaded specimen holder is standard and can be attached to the end or side of the moving platform to increase flexibility. Two specimen holders are provided for mounting contoured specimens. An optional 5 mm spacer set is available to increase the gantry height and accommodate specimens thicker than 22 mm.
Scratching tips
| Each multi-finger scratch/mar tester contains a set of five hemispherical scratching points with a diameter of 1.0 mm |  |
| and hemispherical mar tips with a diameter of 7.0 mm. Both contain a Precision ball made of tungsten carbidewhich is attached to the contact end. |  |
| Optional conical scraper tips are also available, either from Tungsten carbide (0,1mm; 0,25mm; 0,4mm und 0,5mm Durchmesser) |  |
| oder aus Diamond (with 90° 3mil or 90° 3.5mil radius). |  |
Evaluation
Depending on the type of material being inspected, the visual appearance of a scratch is usually indicated by changes in surface topography, colour or brightness. Three methods are normally used:
- Visual evaluation - In this technique, the observer inspects each scratch mark with a controlled light source and rates it on a scale of 1 to 5 (1 = no scratch mark at all; 5 = severe scratch mark). For plastic materials, indicate whether the line shows signs of lightening.
- Width/depth - The operator uses an optical measuring device, e.g. an optical micrometer, to measure the width and/or depth of the scratch.
- Image analysis - Another option would be to use an image analysis technique such as SEM.
Detailed descriptions are recommended when visualising scratches or damage. Points that can be described include surface topography, material deformation, material removal and colour changes. The following examples have been used to describe damage in plastics:
- the scratch is superficial (or deep)
- the scratch is smooth and has a well-defined shape (or is rough and deformed)
- the scratch involves a plastic flow of the material (or cutting, tearing, cracking, flaking, crazing)
- the scratch has visible ripple marks on the underside (e.g. chevron or parabola-shaped)
- a lightening of the elongation is visible (or no colour change)
NOTE: The properties of plastics can strongly influence the evaluation of scratch and abrasion resistance. It is important to be aware of the following factors and take them into consideration. In order to obtain reproducible results, it should be determined whether the evaluation should be carried out immediately after the scratch test or after a certain time (e.g. 24 hours):
- Many plastics have an elastic recovery capacity when the load is removed.
- Many plastics have viscoelastic properties and the stresses in the plastics can relax during loading.
- Plastics can change their structure during the material flow, which can also lead to a change in the mechanical properties of plastics.
Additional information
| brand | Taber |
|---|---|
| Standards | BN 108-13 (Ford), BO 162-01 (Ford), GMN 3943 (General Motors), GMW 14698 (General Motors), LP-463DD-18-01 (Chrysler), NES M0159 (Nissan), PF-10938 (Chrysler) |
| Substrates/substances | Plastics and polymers |
| Mission | Laboratory |
