Textile Adviser: FABRIC TEARING STRENGTH TESTING BY FALLING PENDULUM TYPE TESTER

FABRIC TEARING STRENGTH TESTING:

The term tearing of the fabric is the required force that initiates the tearing in the fabric. The tearing force required to initiate the tearing of the fabric from the split in the centre of the fabric specimen or continuous tearing of the fabric is called tearing strength of the fabric. It is also termed as tearing resistance of the fabric. The tearing strength of the fabric is measured in kilograms, pounds, grams, and Newtons etc. The tearing strength of the fabric is measured in both directions ( warp and weft) separately.

FABRIC TEARING STRENGTH TESTING:

The tearing of the tearing strength of the fabric is performed in the following steps:

APPARATUS USED:

1 - Falling pendulum ( Elmendorf) type fabric tearing strength tester.

2 - Scissor

3 - fabric.

4 - Marking pen

5 - Magnifying glass

6 - Needle

7 - Measuring scale

SPECIMEN PREPARATION:

First of all, the warp and weft directions are identified with the help of magnifying glass. The specimen is cut with the help of scissors. 5 specimens from each direction ( warp and weft) are prepared. The specimen is prepared with the help of a template supplied with a tearing strength tester by the instrument manufacturer.

All four sides of the specimen are aligned accurately by the fraying of the broken ends or picks from the sides with the help of a needle. If we cut an oversized specimen and align one warp side and one weft side before making the final specimen, and place the template just over the bore aligned sides precisely. Now makes the two remaining sides with the help of a template. We can prepare specimens by following this practice. A centre mark is also made in each specimen. Please see the below figure:

TESTING PROCEDURE:

1 - First of all, the pendulum is set at its starting position. The pointer ( force recording mechanism) is set to zero position.

2 - The specimens of the warp set are tested.

3 - The long sides of the specimen are placed in the centre of the gripping clamps.

4 - The centre position of the specimen in the clamps is fixed with the help of the centre mark made in the specimen.

5 - This centre mark is kept in the bottom direction of the clamps.

6 - The bottom side is placed in the clamps in such a way that it touches the specimen stopper precisely.

7 - The top edge of the specimen is kept parallel to the edges of the clamps.

8 - Now, a cut ( slit ) of 20 mm is made in the test specimen with the help of pressing the handle of the slitting knife inbuilt in the instrument.

9 - We are ready to press the release lever. This release lever is pressed manually.

10 - The pendulum falls rapidly and tears the cloth when the release lever is pressed.

11 - The reading is recorded on the notepad.

PRECAUTIONS:

• The specimen should be prepared precisely.

• The clamps should be tightened properly.

• There should be no slippage in clamps during the tearing of specimens.

• The pointer should be at zero position.

FABRIC TEARING STRENGTH CALCULATION:

The calculation of tearing strength is given in below picture: