Tuesday, 2 June 2009

Flex Abrasion Resistance- Determination

Method for determination of Flex abrasion resistance:

1. Cut five test specimens each 200mm. long and of 32 or 38mm width depending upon wheter the number of yarns/dm of the specimen is below or above 200. Ravel the specimen to 25 mm in width by removing from each side approximately the same number of yarns. Do not take two specimens fro the weft test from the same warp ends or any two specimens fro the weft test from the same picks. Take weft specimens at wide intervals.

2 After positioning the bar by means of the yoke holder, place the specimen between the pressure (upper) plate and the reciprocating (lower) plate of the apparatus and locate centrally. with the specified folding bar or folding blade inserted, after being clamped and loaded by removal of yoke holder, distribute the tension exerted by the bar or blade uniformly over the width of the specimen and align the long dimension both above and below the bar parallel to the direction of the reciprocating motion. Position the specimen with the fold at the centre of the upper plate, and the reciprocating plate at the rear of its stroke when the specimen is clamped.

3. Load the pressure plate and the folding bar or blade as required by the material specifications. In the absence of the material specification, the bar load sufficient to produce rupture in excess of at least 100 cycles and preferably in 300 cycles should be used, in combination with the lowest head load (pressure) sufficient to prevent vibration of the upper plate at the start of the test.

The ratio of the bar to head loads shall be 4:1

4. Check the bar alignment after the first 25 cycles. If shifting of bar from its normal position is noticed, discard the specimen and make the proper adjustment.

5. Remove the pills of matted fibres debris interfering with proper contact between the specimen and the folding bar or folding blade during the test if they cause a marked vibration of the pressure plate or otherwise interfere with proper abrasion. The pill should be removed by careful clipping. Do not correct the vibration of the pressure plate due to pilling by applying additional load. Check the position of the specimen after additional cycles to ensure that the removal of the pills has not altered the bar alignment.

6. If the specimen slips in the clamps or tension and pressure upon the folded specimen do not remain constant during the test, or an anomalous wear pattern is obtained, discard such individual measurements and test an additional specimen.

7. Before every test the blade is rinsed with degreasing agent.

8. The end point is determined by abrading the specimen until rupture and number of cycles is recorded.

9. The report should include the following information:

a. Abradent used, bar or blade
b. Average number of cycles required to produce rupture the specimen

Total No of cycles Report to the nearest cycle
Below 200 10
200 to 299 25
1000 to 4999 50
5000 and above 100

c. Tension and pressure used.

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