SATRA TM55

TEST METHOD: SATRA TM55 (formerly PM55)FLEXING RESISTANCE OF UPPERMATERIALS – BALLY FLEXOMETER

MARCH 1999

This method is intended to determine the resistance of a material tocracking or other types of failure at flexing creases. The method isapplicable to all flexible materials and in particular leathers,

coated fabrics and textiles used in footwear uppers.

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Figure 1 – Insertion of the test specimen in the clamps.

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Figure 2 Upper flexing clamp

3. REFERENCES

None.

4. APPARATUS AND MATERIALS

4.1 A flexing machine with:

4.1.1 Pairs of clamps for securely holding each end of the folded test specimen, see Figure 1,having dimensions as shown in Figure 2.

4.1.2 A mechanism for rotating each upper clamp from horizontal through 22.5 ±0.5degrees at a rate of 100 ±5 flexing cycles/minute.

4.1.3 Each lower clamp fixed and in the same vertical plane as the corresponding upperclamp.

4.1.4 A means of counting the number of completed flexing cycles.

4.1.5 For conducting cold tests, a cabinet capable of maintaining an internal atmospherictemperature of -5 ±2°C, and large enough to contain the test machine. If requiredtemperatures down to -30°C can be used.

Suitable machines are available from SATRA, reference STM407, STM408 or STM477.

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4.2 A device such as a press knife for cutting test specimens of the appropriate size. For usewith SATRA apparatus the test specimen should be of dimensions 70 ±5 mm x 45 ±5 mm.4.3 For testing wet specimens:4.3.1 A pipette of volume 1 cm3.

4.3.2 A clean, hard, flat water resistant surface of size greater than 80 mm x 55 mm.4.3.3 A glass rod or scraper.4.3.4 Distilled or deionised water.

4.4 An optical magnifier or stereoscopic microscope with a magnification of approximately10 times.

5. PREPARATION OF TEST SPECIMENS

5.1 The standard test conditions and numbers of test specimens required for variousmaterial types are given in table 1.

Table 1 – Standard test conditions and number of test specimensType of material being testedGrain leatherCoated leatherSuedeCoated fabricTextile

Dry 20°C

22-44

Wet 20°C

222--Dry -5°C

-2-4-

5.2 For each test condition, use the device (4.2) to cut test specimens of size 70 ±5 mm x 45±5 mm from the material to be tested. Cut half of each set of test specimens parallel to the‘along’ direction and half at 90 degrees in the ‘across’ direction. For leather, if the direction ofthe backbone of the animal is known, choose this as the ‘along’ direction. If the backbonedirection is not known, choose the tight direction of the leather as the ‘along’ direction.5.3 If possible, mark the test specimens with an arrow parallel to the backbone and

pointing to the tail. Otherwise, mark the test specimens with an ‘along’ arrow which pointsin a consistent direction.

5.4 Place all of the test specimens in a standard controlled environment of either 23 ±2°C/50 ±2%rh or20 ±2°C/65 ±2% rh for at least 48 hours prior to testing and carry outthe test in this environment. Include details of the conditions used in the test report.5.5 If conducting a cold test, ensure that the environment surrounding the flexing machine(4.1) is at the required temperature, usually -5 ±2°C, and place all the test specimens intothis environment. Flexing of the test specimens should commence 10 ±1 minutes afterthey are placed in the cold environment, and the procedure in sections 6.2 to 6.9 must becompleted within this time.

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6. PROCEDURE

6.1 Place any test specimens that are to be tested wet onto the surface (4.3.2) with theirreverse face uppermost. Spot 1 cm3of distilled water (4.3.4) from the pipette (4.3.1) on tothe reverse surface of the test specimen and use the glass rod (4.3.3) to work it uniformlyinto the material, to within 5 mm of the edge. It usually takes between 1 and 2 minutes forthe water to be absorbed.

6.2 Place the upper clamp (4.1.1) of the flexing machine in a horizontal position.

6.3 For outer materials, fold a test specimen along the longer centre line with the wearingsurface or grain inwards. For footwear lining materials, fold a test specimen along thelonger centre line with the wearing surface or grain outwards.

6.4 Insert one end of the folded test specimen into the upper clamp, as shown in Figure1a, and secure the test specimen in position.

6.5 Fold the test specimen inside out round the upper clamp as shown in Figure 1b. Thewearing surface or grain is now facing outwards.

6.6 Apply just sufficient hand tension to the test specimen so that it is taut and there is noobvious bagginess around the top clamp. Secure it in the lower clamp as shown in Figure 1c.

6.7 Repeat the procedure in sections 6.2 to 6.6 for the remaining test specimen(s) or untilall of the pairs of clamps are full.

6.8 Select a series of inspection stages. Suitable inspection stages are:

Dry testing – 10 000, 25 000, 50 000 and 100 000 flexing cycles.

Wet testing – 1000, 2000, 5000 and 10 000 flexing cycles.

Cold testing – 1000, 2000, 5000 and 10 000 flexing cycles.

6.9 Operate the flexing machine (4.1) at a rate of 100 ±5 flexing cycles/minute.

6.10 When the first inspection stage is reached, stop the machine.

For each test specimen, use the magnifying device (4.4) to assess the flexing damage.Record the damage using the following descriptions:

s

s

s

s

s

sNo effect, or slight creasing or piping.Marked or severe creasing or piping.Slight cracking.Marked cracking.Severe http://wendang.chazidian.complete failure.

In addition, record whether there is any delamination or flaking. Assess wet test specimensfor salt spue and record any spue present as light, marked or heavy.

In order to make damage assessment easier, the test specimens may be removed from theclamps providing they are subsequently reclamped in the same positions. Ignore anydamage to the test specimens caused by the clamps.