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Your location: Home > Related Articles > Analysis of Li Sharu graph principle of Martindale wear tester

Analysis of Li Sharu graph principle of Martindale wear tester

Author:QINSUN Released in:2023-02 Click:159

Martindale abrasion test refers to rubbing the sample along a geometric trajectory under the known pressure and friction mode. The figure is a straight line at first and then becomes wider and wider and forms. It is an ellipse, then narrowed and finally forms a straight line in the opposite direction of the original straight line. By repeatedly rubbing the test piece along the above trajectory up to the specified number of cycles, different methods are described to evaluate the abrasion resistance.

The Martindale Abrasion Tester is used to measure the pilling of fabrics under light pressure. Under the specified load, the round sample is rubbed with the abrasive material (i.e. standard cloth) with the plane motion of the trajectory forming the Lissajous figure. The specimen holder containing the specimen or abrasive is free to rotate about its axis perpendicular to the horizontal plane. Or the specimen holder filledwith the specimen or with the abrasive depends on the test method used. Its trajectory forms a flat friction motion of a complete Lissajous figure, including 16 times of friction, that is, the two outer drive wheels of the Martindale wear tester rotate 16 times, and the inner drive wheel rotates 15 times. The Lissajous figure determined by the norm is a figure formed by changing motion. This movement is repeated diagonally from a circle to a narrowing ellipse until it becomes a straight line, from where it goes back to a widening ellipse to the circle. However, the instruments produced by many domestic small companies that do not have production qualifications and processing techniques do not have the standard Lissajous trace at all, which leads to uncertainty in the test results.

Basic Li Sharu Figure Movement Trajectory:
Remove the material from the grinding table and use woon white sand with a diameter of (100 ± 5) mm and a minimum surface unit of 100 g/m2. The paper is covered on the surface of each sanding table and fixed on the sanding table to ensure that the surface is very smooth.
Sequentially insert the stainless steel sleeves with the same diameter as the shaft of the sample pen into the shaft sleeve of the sample guide plate, install an ordinary ballpoint pen, and make contact with the tip of the pen with the surface of the paper. Rotate the instrument so that the number of rubs is 16 times to form a completed Lissajous figure.
Draw two parallel lines that just intersect the outer curves on the two opposite sides of the Lissajous figure. Draw two more parallel lines for the other two sides, making sure the lines intersect perpendicularly. Measure with an accuracy of ± 0.2 mm on each side, using an appropriate method. Check the 31 drawn lines, it\'s importantgrijk to check the symmetry of the Lissajous figure.

General rules
The Martindale Abrasion Tester consists of a base equipped with a grinding table and a transmission. The transfer device includes 2 outer wheels and 1 inner wheel. This mechanism ensures that the movement trajectory of the guide plate of the sample holder forms a Lissajous figure. Note: The Martindale instrument produces near-perfect Lissajous movements.
The guide plate of the sample luminaire moves in a plane driven by the transmission device, and each point of the guide plate represents the same Lissajous figure.
The sampler\'s guide plate is equipped with a bearing seat and a low-friction bearing, which drives the sampler\'s pin shaft to move. The lower end of each sample mounting pin is inserted into the corresponding sample mounting socket and a loading block can be placed on the top of the pin.places.
Specification holder including sleeve, insert and pressureTighten the nut.
The tester must be equipped with a preset counting function to record the number of rubs.

More about: Martindale Abrasive Tester