Know What You Wear

Sunday, May 27, 2018

Different Types of Seam Used in Denim Jeans Production

Denim, a cotton woven fabric, may be the most considered article of style today. Denim is cut and sewn in an assortment of clothing types fit for all ages, seasons and events. Denim has achieved so much fame that if we glance around, we will doubtlessly see some individual wearing denim in our midst. Currently, more than simply supplementing a tough style, the denim has ended up as appropriate for any event. Denim is being worn regardless of demographic contrasts. Denim material is identical to familiar jeans and is a tough twill material that has the well-known slanting ribbing.

A seam joins more than one piece of material together, and the type of seam used depends on the product to be sewn. Seams in denim have different levels of complexity depending on the design of the product. The different seams used in the production of denim jeans are discussed in this article. Considering the requirements of a seam on the outside leg of a pair of jeans and, by contrast, the type of seams that go into attaching belt loops and pockets:
  • There may be an uneven pressure on jeans owing to leg movements.
  • There is a gradual build up of stress loading on the seam of the jeans.
  • Strong seams are required throughout the garment to ensure the product performs as intended and does not fall apart.
You may also like: Seam Classification and Quality of Seam in Garments
 
One factor that these and other seams have in common is that the seams must combine the required standards of appearance and performance while ensuring economy of production. The aesthetic characteristics of a seam are usually influenced by the accuracy of the stitching, the visibility of threads of differing colour from each other and the surface of the fabric. Seam performance relates to the strength, extensibility, durability, security and comfort as well as maintenance of specialist fabric properties. Seam grinning, as shown in Figure-1, is when the fabric is under stress at the seam area and the stitches are exposed on the face side of the fabric.
Seam grinning on jeans outside leg seam
Figure-1: Seam grinning on jeans outside leg seam
Factors influencing the strength and extensibility of a stitch line within a seam include:
  • Stitch density (stitches per centimetre).
  • Thread tension (static thread tension setting on the sewing machine).
  • Thread properties (strength and elasticity determined by fiber type).
  • Fabric integrity (cover or tightness factor).
The seam performance relates to:
  • Strength.
  • Aesthetic appeal.
  • Extensibility.
  • Durability.
  • Ease of assembly.
  • Security.
  • Comfort in wear.
Different Types of Seam Used in Jeans Manufacturing:
There are hundreds of different seam types but they are basically categorized into six simple categories, described as follows.
  1. Superimposed seams
  2. Double lapped seams
  3. Bound seams
  4. Hems
  5. Zippers and belt loops
Superimposed seams:
The seam of class-1 is called superimposed seam. This is the most common & mostly used seam for joining fabrics. Generally, two or more plies of fabric are laid on top of each other superimposed in the same orientation. They are stitched near the edge with one or more rows of stitching, as shown in Figures-2, 3 and 4. The rows of stitching may be sewn simultaneously or consecutively.

Superimposed seam ply alignment
Figure-2: Superimposed seam ply alignment.
Overlapped superimposed seam ply alignment
Figure-3: Overlapped superimposed seam ply alignment.
Combination stitched superimposed side seam
Figure-4: Combination stitched superimposed side seam.
Double lapped seams:
These are:
  • Two or more plies are lapped together, overlaid, plain or folded.
  • Secured with one or more rows of stitching.
  • One of the most common is the double lap felled seam with two or more rows of stitching.
  • This provides a strong seam with fabric edge protection.
  • Often used on the side seam of jeans, other denim products and tents.
This seam type exhibits very high strength and is used extensively where durability and flexibility is needed in the garment, as shown in Figures-5 and 6.
Double lapped seam ply alignment
Figure-5: Double lapped seam ply alignment
Double lapped seam
Figure-6: Double lapped seam.
Bound seams:
These are formed by:
  • Folding a binding strip around the raw fabric edge(s) and securing with one or more rows of stitching.
  • This produces a secured neat seam on an edge often exposed to view or wear.
  • It is also often used in other areas of manufacture such as luggage.
This type of seam is normally found on the waistband of the garment, as shown in Figures -7 and 8.
Schematic view of bound seam
Figure-7: Schematic view of bound seam.
Bound seam of waistband
Figure-8: Bound seam of waistband.
Hems:
There are two main areas of the garment where hems are used: on the bottom hem of the jeans, namely the leg, and on areas such as pockets and zippers. The leg hems as shown in Figures-9 and 10 are double folded in one operation on a leg hemming machine. The pocket hems as shown in Figure-11 are folded once onto the fabric and top stitched with either one or two rows of stitching.

Schematic view of hem
Figure-9: Schematic view of hem.
Hem of denim jeans leg
Figure10: Hem of denim jeans leg.
Hemmed top of patch pocket
Figure-11: Hemmed top of patch pocket.
Zippers and belt loops:
The zippers and belt loops are similarly attached using a combination of superimposed seams. The most common stitching of a zipper on denim jeans is called the J-stitch, shown in Figure-12. It looks like a letter “J” because of the stitch on the front of the garment.

J-stitched fly zipper surround
Figure-12: J-stitched fly zipper surround.
Belt loops are created through a folder that butts the two edges of the fabric together and the sewing head stitches them together using a flat seam (type 402), as shown in Figures-13, 14 and 15.
Schematic view of belt loop fold
Figure-13: Schematic view of belt loop fold.
Belt loop attached to waistband and jeans body
Figure-14: Belt loop attached to waistband and jeans body
Belt loop showing 402 stitches in the underside
Figure-15: Belt loop showing 402 stitches in the underside.
References:
  1. Denim : Manufacture, Finishing and Applications. Edited by Roshan Paul
  2. Sustainability in Denim. Editors: Subramanian Muthu
  3. http://textilelearner.blogspot.com/2012/02/seam-uses-of-seam-production-of.html