Seam Performance and Problem

Seam performance affects both the aesthetics and performance of a garment and are important to its saleability and longevity. It significantly depends on the interrelationship of fabric, thread, and needle; stitch and seam selection; performance of sewing pressing equipment; material handling; and appropriate operation and maintenance of equipment.

I. Seam performance
Seam performance relates to the elasticity, strength, and flexibility of a seam. These properties are related to fabric characteristics, selection of stitch and seam type, thread type and size, and density of stitches (SPI)

Elasticity
Elasticity involves two factors, elongation, and recovery. Seam elasticity is the degree that seam recovers to its original length immediately after elongation. Garment such as leotards and swimsuits require high elongation and recovery of both fabric and seams for satisfactory service.

Elongation
Elongation is the amount that a seam can be stretched without braking. Recovery is the return of seam to its original length when stress is removed.

Strength
Seam strength is an important factor in determining the durability of a garment. Seam strength is determined by resistance to pulling force and abrasion. Seam tenacity is the amount of force necessary to break the fabric or weakest stitch of seam

Flexibility
Seam flexibility affects the drapeability, comport, and abrasion resistance of apparel. Flexible seam allow foe more body conformity and movement.


II. Seam problem
Seam problem that effect appearance and performance include distortion, skip stitches, grain, thread breakage, slippage, and yarn severance. Seam failure can cause costly repair as well as rejection.

Distortion
Distortion is the disruption of the fabric surface or the deformation of a garment. Incorrect handling during garment assembly often contributes to distortion.

Skipped stitch
Skipped stitches are a common sewing problem affecting quality, seam performance, and aesthetics of a garment. It is caused by a failure in stitch formation when the needle thread is not picked up by the hook or looper.

Seam grain
Seam grain is a separation of a sewn seam as a result of transverse stress that allows the stitches and thread to show.

Thread breakage
Thread breakage is a common problem that has many causes such as needle heat; insufficient ply security; incompatibility of needle, thread, and fabric; and defective machine parts or adjustments.

Slippage
Seam slippage occurs in woven fabrics when yarn s slide together along other yarns or a line of stitching, thus allowing the seam grain. Most slippage occurs in seam that runs parallel to warp yarn. Slippage is more likely to occur in fabrics that have filament yarn, low thread count, unbalanced weave.

Yarn severance
Yarn severance, or needle cutting, is the breakage of fabric yarns that occurs during stitching because of incompatibility of needle, fabric, and sewing speed. Causes of yarn severance are damaged needles and incorrect needle type, point, and size relative to fabric being sewn.