What is Tearing Test? How Tearing Strength Tester Works?

Tearing Test

This process defines the tearing test for garment. The equipment called tearing strength tester. This process done for both side (vertical and horizontal). For better result we take an average of three tearing test. Standard acceptable tearing strength is 2lbs (standard for GAP buyer).This tearing test covers the determination of the force required to propagate a single rip tear starting from a cut in fabric and using a falling pendulum type apparatus. This test is applied only for woven fabric.

Method we use:

• FOR USA / CANADA: ASTMD 1424
• FOR EUROPE: BS EN ISO 13937-1

Procedure of tearing strength tester

Cut the swatch of testing material as per specific template of tearing strength meter. Align this swatch between two-iron rods. Cut this aligned swatch with given blade in tearing strength tester. Make sure that meter scale needle is on zero. When everything fixed up, press the treadle and take the reading of meter scale. For instance, if reading comes 48 then formula will be

SCALE READING X 64   X 2.2

————————————

1000

48        X 64 X 2.2

———————-          = 6.7 lbs

1000

Button Hole Tearing Strength Tester

To determine the maximum force required to break a button hole on rugby garments.

Principle: The prepared test tape, into which has been sewn a buttonhole, is held by grips of a specific dimension and extended at a constant rate until it ruptures (breaks).  The force at which this occurs is then recorded.

Equipment: Constant rate of Extension Tensile testing instrument with the following:

• Load cell with a maximum of 1,000N capacity
• 100mm/minute constant rate of extension
• Distance between upper and lower sets of grips is 30 mm
• Pneumatic Rubber faced grips, these must be selected to give a grip area on the test specimen which is not less than width of the tape.
• For PC operated machines, appropriate software (to DIN 53858 )
• Printer capability

Calibrated metal ruler

Sewing Thread – same colour and quality as that used in the final  finished garment

Tearing Test One

Sample  Preparation

1. Cut a length of tape 500 mm long.
2. Measure in 100mm and sew a buttonhole central in the crosswise direction. (The length of the buttonhole must be 10mm)
3. Repeat, making two further buttonholes
4. Cut the tape into 50mm lengths, so that each length contains one buttonhole which is in the centre of the 50mm length

Tearing Test Two

Sample  Preparation

1. Cut a length of tape 500 mm long.
2. Measure in 100mm and sew a buttonhole central in the lengthwise  (The length of the buttonhole must be 10mm)
3. Repeat, making two further button holes
4. Cut the tape into 50mm lengths, so that each length contains one buttonhole which is in the centre of the 50mm length

Another Tearing Test Procedure

Test  1

Using an Automatic Constant Rate of Extension Tearing Tester

1. The programme is automatic. The test speed is 100mm per minute.
2. Use the 75mm x 25mm rubber faced grips on the rear and 25mm x 25mmm grips on the front.
3. With the correct grips in place set the distance between upper and lower sets of grips to 30mm, this should be checked using a calibrated metal ruler.
4. Select the correct programme and input the appropriate machine settings and test details etc.
5. Fix the tape in the upper grips, so the tape hangs in the lengthwise
6. Close the upper grips
7. Allow the tape to hang under its own weight and secure the tape in the lower grips so that the buttonhole is central between the grips.
8. Cose the lower grips
9. Set the cross head in motion.
10. Te maximum force at which the buttonhole ruptures (breaks) will be recorded
11. Repeat the above procedure for the remaining 2 prepared tapes.

Test  2

Follow the above  test procedure  from Part 1 form a) to d) then at step e) proceed as follows:-

1. e) Fix the tape in the upper grips, so the tape hangs in the cross wise, width

Now continue with procedures f) to k) as Part 1

Test Report

Using the adidas Group standard report format:

Report the average of the 3 results for each direction tested.

Preparation of the test samples :

Each raw test sample must have the following size : 10 cm x 7,5 cm.

The test sample has two notches : a small and a big. You can cut the sample with a punch or you can draw it and then cut it with scissors.

For the measure of  weft tearing, the length of the sample must be parallel to the weft.

For the measure of  warp tearing, the length of the sample must be parallel to the warp.

For each test, cut 10 samples for the weft and 10 samples for the warp.

The initiated tear must be 2 cm long. It must be perpendicular to the side with the big notch and in the middle of it. This initiated tear is realised with the knife of the apparatus.

Tearing Test conditions :

With the setting level, place the apparatus in such a way that the pendulum is in a vertical plane.

Adjust the needle in such a way that it stop on zero when the apparatus is used without sample.

Wind on the pendulum to line up the 2 clamps.

Put the needle in contact with the drive stop of the apparatus. Place the sample in the clamps in such a way that the warp or the weft is parallel to the upper sides of the clamps.

With the knife of the apparatus, cut an initiated tear parallel to the warp or the weft depending on the case. Release the pendulum. Note the tearing test on the scale of the apparatus.