Purpose:
For sewing and seam performance, thread tensile strength and elongation are important factor. Adequate strength and elongation is needed for varying the fabric, the seam type or purpose and the end use of the sewn product. For compatible machine works, adequate thread elongation measurement is also necessary. Looped thread single strand tensile strength would be measured to find out seam strength. This measurement would give specific stress that seams can withstand before breakage. Seam strength is important for the sewn product serviceability. Seam failure determines serviceability of the product. Seam failure occurs through thread failure, fabric failure or seam slippage. Seam failure test is done to figure out the best combination to increase thread, fabric and seam construction durability.
(Please change world you can lab read instructions)
Materials:
100% cotton thread, 100% PE thread, Blue PE-Spandex fabric, 100% white cotton plain weave, scissors, Tensile Testing Machine (Instron), thickness caliper, scissors, masking tape.
Weight of Thread
PE: 25.19tex
Cotton: 47.04tex
Weight of Fabric
Cotton: 229.06g/m2
PE-spandex: 235.13g/m2
Procedure:
6 threads of 26cm were cut for each PE and cotton to make 3 loops for each fiber type. Two pieces of thread are looped together with end of loop taped with masking tape. Place taped loop between upper and lower jaws of the Instron. Using the software, attain breaking strength and % elongation at break and record them. Record whether break occurred near top or near bottom, and whether loop was broken or straight side was broken. Using the recorded data, calculate breaking tenacity in cN/tex and determine tex. Then calculate mean elongation for each thread.
For seam strength measurement for woven fabrics, cut three of 4 inch specimens that is 1 inch from the top of the seam. Then drew a line perpendicular to the seam 1.5 inches/40mm from each edge of each specimen. Thickness were calculated with the caliper for the Intron data. Clamped between two jaws so that seam is centered horizontally between two jaws. Instron machine was used to calculate the breaking force in Newtons at seam break. Record the breaking behavior marked as either thread break, fabric break, seam slippage or a combination. Then calculated mean breaking force for each seam/stitch.
(Please change world you can lab read instructions)
Data:
A. Thread Loop Breaking Strength: Loop elongation
Instron parameters for thread loop breaking strength and elongation
Load cell: 10kNtension cell; calibrate with 1 kg
Gage length: 250 ± 3mm
Crosshead speed: to give time to break of 20 ± 3s
100% polyester thread
Breaking behavior Extension(mm) Load(N) Tenacity(N/Tex)
Bottom loop broken 33.93 4.50 0.20
Bottom loop broken 37.03 7.22 0.33
Top loop broken 35.83 7.39 0.02
Average 35.59667 6.37 0.183333
St.dev 1.563117 1.621697 0.155671
100% mercerized cotton thread
o Weight/ length * 1000m/g= 0.0785g/ 1.5m * 1000m/g= 52.3 tex
o Breaking tenacity (using mean breaking strength)= 0.42 N/tex
Specimen 1 Specimen 2 Specimen 3 Mean Standard Deviation
Breaking strength from the machine (N) 23.09 21.58 22.52 22.40 0.76
% Elongation at break (in percent) 4.59 4.85 4.97 4.80 0.19
Where break occured Bottom on the loop Bottom on the loop Bottom on the loop
Tex Calculation (tex = g/1000m)
27cm PE = 0.0068g
0.0068g/27cm x 100cm/1m x 1000m/g = 25.19Tex
27cm cotton = 0.0127
0.0127g/27cm x 100cm/1m x 1000m/g = 47.04Tex
Breaking Tenacity = F(breaking force)/T(linear density in tex)
= 6.37N/25.19tex x 100cN/1N = 25.29cN/tex
Result difference = 0.1833N/tex – 25.29cN/tex = 18.33cN/tex – 25.29cN/tex = -6.96cN/tex
B. Seam Strength in Woven Fabrics
Seam strength in woven fabrics
100% cotton plain weave
Instron Parameters
Jaws were 1.5inches/80mm apart
Force range to break occurs between 10-90% of full scale force (305mm/min)
512 SSa seam(mock safety stitch), 100% polyester thread
Failure mode Occurrence thickness(mm) Load(N)
Fabric break top and bottom Near Seam 0.39 292.68
Fabric break only bottom Near Seam 0.35 306.81
Fabric break only top Near Seam 0.33 323.83
Average 0.356667 307.7733
St.dev 0.030551 15.59733
301 SSa seam(lockstitch), 6 SPI seam, 100% polyester thread
Failure mode Occurrence thickness(mm) Load(N)
Seam slippage Seam 0.34 183.32
Seam slippage Seam 0.35 175.86
Seam slippage Seam 0.35 199.37
Average 0.346667 186.1833
St.dev 0.005774 12.0137
301 SSa seam, 12 SPI seam, 100% polyester thread
Failure mode Occurrence thickness(mm) Load(N)
Combination: Fabric break top and bottom and seam Near Seam 0.33 303.26
Combination: Fabric break only bottom and seam Near seam 0.34 306.25
Combination: Fabric break only bottom and seam Near seam 0.3 306.61
Average 0.323333 305.3733
St.dev 0.020817 1.839031
PE-spandex laminated seam
Failure mode Occurrence thickness(mm) Load(N)
Fabric break top Near top 0.36 343.65
Fabric break top Near top 0.36 332.00
Fabric break top Near top 0.37 347.44
Average 0.363333 341.03
St.dev 0.005774 8.046533
Use date for responses
Result & Discussion
( have to write detail and use data and uploaded file infomations)
Conclusion:
Question:
1. Do the polyester and cotton threads differ on both strength and elongation? Does same one show both greater breaking strength and greater elongation?
2. Which thread would you consider best for general-purpose use, and why?
3. Did you see a consistent type of seam failure foe all seams, and if so, what failed?
4. On the basis of your seam tests, do you feel that 6 SPI would be an adequate general-purpose stich length?
5. On the basis of your tests, would you consider the two seam configurations to be of equal strength?
6. What differences between these two seams might dictate where and hoe they are used in garments?