AAFES TEST METHOD

A-12: Seam Strength

Issue Date: 30 Apr 1993

Revision Date: 08/18/2004

1. PURPOSE AND SCOPE:

   To determine strength of seams in woven fabrics. Seam failure in a garment can occur because of either the failure of the sewing thread, leaving the fabric intact, or fabric rupture, leaving the seam intact or both breaking at the same time.

2. PRINCIPLE:

   The breaking force required to effect rupture of sewn seams is measured using the Grab Test Procedure.

3. REFERENCE:

   ASTM D 1683-90a, Standard Test Method for Failure in Sewn Seams of Woven Fabrics.

4. APPARATUS:

   Tensile testing machine, Instron Model 4206

5. PROCEDURE:

   5.1 Cut three specimens with the 4 inch width parallel to the stitch line and 6 inches long.

   5.2 Condition the specimens for a minimum of 2 hours at 21° +/- 1C (70° +- 2F) temperature and 65% +/- 2% relative humidity.

   5.3 Set the gauge at 25 mm (3 in.) with 100 to 1000 lbs. capacity tension load cell.

   5.4 Set the speed at 30.5 cm (12 in.) per minute.

   5.5 Place the test specimen in the jaws.

   5.6 Press "up" key on crosshead control panel.

   5.7 When the seam breaks, stop the machine, and read breaking force on digital readout panel.

   5.8 Return the jaws to the original gauge length 25 mm (1 in.).

   5.9 Repeat Steps 5.5 to 5.8 on the remaining test specimens.

6. EVALUATION:

   Calculate the average seam strength of the three specimens.

7. REPORT:

   Report the above figure as the seam strength of the sample tested. Seam strength can be reported in either pounds or grams. If there was no clear seam break, also indicate nature of the failure such as fabric rupture.

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