Stitch Type

Stitch Types

Stitches

Stitches: A stitch is a unit or loop in a seam. It is produced by three principle methods of stitch formation:

3 Methods of Stitch Formation

Inter looping

Intra looping

Inter locking

The loop of one thread passes through the loop of another thread

The loop of one thread passes through the loop of the same thread

The loop of one thread passes over the loop of another thread

Stitches: Difference between lockstitch and chainstitch

Chainstitch Machines

Lockstitch Machines

Stitches are formed by two or more sets of threads: 1 needle thread and 1 looper thread. Threads are bound together by interlacing and Inter looping, this forms a chain of thread on the underside of the fabric, creating the chainstitch.

Stitches are formed by at two sets of threads: 1 needle thread and 1 bobbin thread. Threads are bound by interlacing. The rotary hook containing the bobbin catches the needle thread after it goes through the fabric, the hook then carries the needle thread around the bobbin and the needle pulls the needle thread back up to the top of the fabric. The needle thread and bobbin thread become interlocked, forming a lockstitch.

Appears like lockstitch above and double chainstitch below.

Appearance is similar on both sides of the fabric.

No bobbin to change and interrupt sewing.

Operators must remove and replace the bobbin frequently.

More cost effective than lockstitch.

Replacing the bobbin interrupts productivity/increases labor costs. Some bobbins are automatically wound during sewing; others are purchased pre-wound from thread companies.

Looper threads feed from large cones.

Strength is higher than lockstitch.

Strength is lower than chainstitch.

Possibility of seam pucker formation is more than lockstitch.

Possibility of seam pucker formation is less than chainstitch.

Extensibility is 30%.

Extensibility is 30%. Sometimes less than that.

Chainstitch machine speed 8000 SPM.

Lockstitch machine speed 6000 SPM.

Interlacing: To cross one another, typically passing alternately over and under, as if woven together; intertwine. Inter looping: The loop of one thread passes through the loop of another thread. Extensibility: Capable of being extended.

Stitch: Designation

Textile Stitch Types / Classification There are 70 types of stitches. Among them 18-20 types of stitches are widely used in the garment industry. These stitches are divided into 6 classes.

1. Class-100 Single Needle Chainstitch 2. Class-200 Hand Stitch 3. Class-300 Lockstitch 4. Class-400 Multi-Thread Chainstitch 5. Class-500 Overedge Stitch 6. Class-600 Covering Chainstitch

Stitch Quality Stitch quality is measured by:

Stitch Size - Length, width and depth Tension - Too much causes puckering Sequence - Consistent stitching and seam formation Elasticity - Elongation and recovery (return of seam to its original length) Strength - Resistance to pulling force and abrasion Thread Severance - Using the correct thread and needle according to fabric sewn

Stitch Classes Stitch classes are designated and identified by the first digit of a “3 digit numeral system”. The type of stitch within each class is designated and identified by the 2 nd and 3 rd digits.

Stitch: Class-100 (Single thread chainstitch)

Class-100 (single thread chainstitch): The stitch is formed by a needle thread passing through the material and inter- looping with itself on the underside of the seam with the assistance of a spreader. In this stitch, one loop passing through another loop of same thread.

 Not the nicest or most durable  Economical, only 1 thread at a time  Plain on face, single chain on the back  Lacks durability for certain locations on garments  May unravel or come undone too easily for quality apparel

Uses:

Secure hems

• •

Sew on buttons and make buttonholes

• The 101 is used for basting (closing of paper bags, etc.)

Applications: •

Used in lap and flap positioning

Temporary joining

•

• Basting, hemming, blind stitching, button attaching, button holing purposes.

Disadvantages: •

Security of stitch is very poor. If one end of the thread is pulled, then the whole seam will come undone.

Variation:

• Blind Stitch: Joins layers of fabric without the needle thread fully piercing the top layer • Needle thread barely catches a few yarns of the outermost fabric layer • Should be unnoticeable, or nearly so, from the outside of the garment • Used for hems and is easily removed from hems

Stitch: Class-100 (Single thread chainstitch)

Class-100 Subclasses:

Stich Class 101 (chainstitch): Stitch is formed by a needle thread passing through the material and inter-looping with itself on the underside of the seam with the assistance of a spreader. Single thread chainstitches are often used for temporary stitching (i.e. basting) or for blind stitching. Particular care is required to prevent runback from the last stitch.

Thread consumption ratio=1 : 5

Stitch Class 103 (blindstitch): Stitch is formed with one needle thread which inter-loops with itself on the top surface of the material. The thread passes through the top ply and horizontally through portions of the bottom ply without penetrating the full depth. One thread and a curved needle which passes from left to right, entering and exiting from the same side of the material carrying a needle thread which is intercepted by a blind looper. The thread inter-loops with itself on the top surface. Particular care is required to prevent runback from the last stitch.

Thread consumption ratio=1 : 4.5

Stitch: Class-200 (Hand Stitch and their machine simulations)

Class-200 (hand stitch and their machine simulations): Stitch formation by hand with exception of the 205 stitch, which simulates a hand running stitch but is a machine made version. Sometimes this stitch is referred to as Saddle Stitch*.

 Only 1 thread used  Machine-made versions of hand stitches used for decorative purposes  Much faster produced than hand stitching  Finely tailored and couture clothing often feature real hand stitches  Hand stitches lower production speeds and increase costs

* Saddle Stitch: A special type of stitch which is formed by a Pique Stitch Machine using thick thread. It is used in cowboy jeans.

Uses:

• Sewing on closures such as snaps and hooks and eyes • Decorative details

Applications: •

Expensive garments

Basting, tacking and repairs

•

• Stitch type-209 is used for the edges of jackets

Disadvantages: •

Time consuming

High cost

• •

Length of stitching is not consistent

• Thread may become untwined due to friction • Rare in use

Stitch: Class-200 (Hand Stitch and their machine simulations)

Class-200 Subclasses:

Stitch Class 202 (single thread): Hand stitch using one needle thread.

Stitch Class 205 (single thread): Machine stitch using one needle thread.

Stitch Class 209 (single thread): This type of stitch is formed with one thread. It is a machine made version of traditional hand stitching sometimes referred to as a saddle stitch.

Thread consumption ratio = 1 : 1.4

For more information please see our Hand Stitching Basics presentation.

Stitch: Class-300 (Single thread lockstitch)

Class-300 (lockstitch): The stitch is formed by two or more groups of threads inter-lacing loops of one group are passed through the material and are secured by the thread of the second group. One group is referred to as the needle thread and the other as the bobbin thread.

 Composed of a needle thread inter-locked with a bobbin thread between the piles of fabric  Lockstitches are not the nicest and, while durable, are not the most durable

Uses:

Frequently used to attach pocket, collars, cuffs and facing Top stitching, button holing, button attaching, blind stitching, etc.

Advantages: •

Flat and smooth on both sides, causing less bulk and making them comfortable • Very strong, tight and secure with 30% more extensibility • Requires less thread than many other stitches

Disadvantages: •

Bobbin thread capacity is low requiring frequent stops to reload the bobbin • Not suitable for knit fabric sewing • Rupture easily if stretched or strained • Affected by unbalanced tension more than other stitch types; this can cause puckering • More labor cost is usually involved than chainstitches • Plain or straight stitch: Same stitch made by conventional, home sewing machines. Single, straight, continuous row of stitches on both sides of fabric. Most frequently used stitch in the production of apparel and other soft goods. • Zig-zag stitch: Used for elasticity. These stitches stretch when the seam is stretched so the stitches don't rupture. More common in home sewing.

Variation:

Stitches: Class-301 (Subclass)

Stitch Class 301 (lockstitch): Stitch is formed by a needle thread passing through the material and interlocking with a bobbin thread with the threads meeting in the center of the seam. Stitch looks the same on the top and the bottom.

Thread consumption ratio=1 : 2.5

This type of stitch is formed with 2 threads:

1 Needle thread (A) 1 Bobbin thread (B)

Stitch type 301

The loop of thread (A) is passed through the material and inter- laced with thread (B). Thread (A) is then pulled back so that the inter-lacing is midway between surfaces of the material or materials being sewn.

Ideally, this stitch should have a 1 : 1 ratio of needle to bobbin thread.

Variation: Stitch Class 301 (twin needle lockstitch): Same as 301 except that two rows of stitch are formed. Typical needle spacing is 1/4″ but the machines are available from 3/16″ up to 1″.

Face Side

Underside

Thread consumption ratio=1 : 2.5

Stitches: Class-304 (Sub-Classes)

Stitch Class 304 (zig zag): The 304 stitch formation is commonly referred to as the zig-zag Lockstitch with a needle and bobbin thread that are set in the center of the seam. To produce the zig-zag appearance, the needle bar moves laterally as the material is fed creating a symmetrical zig zag pattern. Also used for bartacking, lockstitch button sewing and button holing. Thread consumption ratio=1: 5.5

Stitch type 304

This type of stitch is formed with 2 threads:

1 Needle thread (A) 1 Bobbin thread (B)

The loop of thread (A) is passed through the material and inter-laced with thread (B). Thread (A) is then pulled back so that the inter-lacing is midway between surfaces of the material or materials being sewn.

Ideally, this stitch should have a 1 : 1 ratio of needle to bobbin thread.

Face Side

Underside

Stitches: Class-306, 313, 314 (Sub-Classes)

Stitch Classes 306 (lockstitch blind stitch): This is a 2 thread lockstitch blind stitch using 1 needle thread and one hook (bobbin) thread. Typically used for hemming or seaming lining to shell fabric.

Stitch Classes 313, 314 (Lockstitch blind stitches): These less common stitches are used for linings and the inside components of waist bands for men dress slacks.

Stitch Classes 315 (Triple Zigzag stitch): This is a two thread three step zigzag lockstitch using one needle thread and one hook (bobbin) thread. Typical uses are seaming, topstitching, coverstitching knits or woven where wide coverage or greater stretch is required (usually in foundation garments).

Stitches: Class-400 (Multi-Thread Chainstitch)

Class-400 (multi-thread chainstitch): This stitch is formed with two or more groups of threads loops of one group of threads are passed through the material and are secured by inter-lacing and inter-looping with loops of another group. One group is referred to as the needle thread and the other as the looper thread. It has an appearance of a lockstitch on top but has a double chain effect formed by a looper thread on the underside.

 Widely used in the apparel industry  Also called double locked chainstitches  Appears as lockstitch on top and a chainstitch on bottom

Uses:

Setting elastic waist bands Decorative stitching on belts

• •

Advantages: •

More extensible stitches than lockstitches • Less costly to produce; don't require bobbins

Disadvantages: •

Create a looser seam than lockstitches

• Require more thread; creates a bulkier seam • Thread abrades away more easily than lockstitch; less durability • Thread loops may catch on jewelry

406-407 Bottom Covering Chainstitches: •

2 or 3 parallel rows of stitching

Used:

• Attach elastics and bindings to underwear • Hem T-Shirts • Flatten seam allowance of seams after they are sewn

Stitches: Class-401 (Sub-Classes)

Stitch Class 401 (chainstitch/ twin needle chainstitch): Stitch is formed by 1 needle thread passing through the material and inter-looped with 1 looper thread that is set on the underside of the seam one needle thread (A) and one looper thread (B). Loops of thread (A) are passed through the material and interlaced and inter-looped with loops of thread (B). These inter-looping's are drawn up against the underside of the bottom ply of the material being sewn. Thread consumption ratio=1 : 5.5

Stitch type 401

This type of stitch is formed with 2 threads:

1 Needle thread (A)

1 Looper thread (B)

The loops of thread (A) are passed through the material and inter-laced and inter-looped with loops of thread (B). These inter-looping's are drawn up against the underside of the bottom ply of the material being sewn.

Face Side

Underside

Stitches: Class-404 (Sub-Classes)

Stitch Class 404 (zig zag chainstitch) Stitch is formed is similar to the 401 stitch. To produce the zig-zag appearance, the needle bar moves laterally as the material is fed. Thread consumption ratio=1 : 7

This type of stitch is formed with 2 threads:

1 Needle thread (A) 1 Looper thread (B)

The loops of thread (A) are passed through the material and interlaced and inter-looped with loops of thread (B). These inter- loopings are drawn up against the underside of the bottom ply of the material being sewn.

Stitch type 404

Face Side

Underside

Stitches: Class-406 (Sub-Classes)

Stitch Class 406 (bottom coverstitch): Stitch is formed by 2 needle threads passing through the material and inter- looping with 1 looper thread with the stitch set on the underside of the seam. Thread consumption ratio=1: 15.5

This type of stitch is formed with 3 threads:

2 Needle threads (A & A1) 1 Looper thread (B)

Stitch type 406

The loops of the needle threads (A & A1) are passed through the material and inter-laced and inter-looped with loops of thread (B). These inter loopings are then drawn against the underside of the material being sewn.

Face Side

Underside

Stitches: Class-407 (Sub-Classes)

Stitch Class 407 (bottom coverstitch): Stitch is formed by 3 needle threads passing through the material and interlacing with 1 looper thread with the stitch set on the underside of the seam. Thread consumption ratio=1: 20

This type of stitch is formed with 4 threads:

Stitch type 407

3 Needle threads (A, A1 & A2) 1 Looper thread (B)

The loops of the needle threads (A, A1 & A2) are passed through the material and inter-laced and inter-looped with loops of thread (B). These inter loopings are then drawn against the underside of the material being sewn.

Face Side

Underside

Stitches: Class-408 (Sub-Classes)

Stitch Class 408 (bottom coverstitch): This stitch is two rows of 401 two thread chainstitch with a top covering thread laid on the upper surface of the material being sewn. Thread consumption ratio=1: 17 This stitch is two rows of 401, two thread chainstitch with a top covering thread laid on the upper surface of the material being sewn.

This type of stitch is formed using 5 threads:

2 Needle threads (A & A1)

Stitch type 408

2 Looper threads (B & B1)

1 Top covering thread (C)

The loops of the threads (A & A1) are passed through the material and interlaced and inter looped with loops of threads (B & B1). The top covering thread (C) is laid between and around the needle threads on the surface of the material. The inter looping of the needle and looper threads are drawn up against the underside of the bottom ply of the material being sewn.

Face Side

Underside

Stitches: Class-500 (Overedge Stitch)

Class-500 (overedge stitch): The stitches under this class are produced with one or more threads (one needle thread and two or more looper thread) and at least threads of one group around the edge of the fabric to stop fraying (i.e. threads from the edge of the fabric can not come out). The knife of the machine cuts the edge first producing a clear edge for seaming. Sometimes it is used for decorative purpose.

 May also be called serging, overlock, overseam, overcast, Merrow (type of machine)  These are formed over the edge of fabric, encasing the edge in thread inter looping  A finish for raw edge of fabric to prevent fabric from raveling  Widely used in the apparel industry

Applications: •

Edge neatening of knitted fabrics

• Where extensibility of stitches is important (i.e. Polo tees, sports and dance garments)

Advantages: •

Most extensible (able to be extended) stitches because of their many inter looping • Require narrow seam allowances, conserving fabric • Reduced labor cost of finishing seams

Disadvantages: •

This stitch type is prone to seam grinning (the threads are exposed when the seam is pulled at right angles to the line sewn). • The finish may be somewhat bulky due to the complexity of the seam construction • Stitch width is about 3-5 mm • Require more thread than most overstitch types • Thread can unravel if caught and broken on sharp object

Stitches: Class-500 (Overedge Stitch)

Variations:

• Stitch Class 515 (safety stitch): Combine a row of overedge stitches with a row of straight lockstitches or chain stitches  Makes a very durable seam  The row of straight stitches is parallel to the overedge stitches  Used on shirts/blouses, jackets, pants, jeans, and skirts • Stitch Class 515 (mock safety stitch): Consists of a single row of stitches instead of 2 rows  On the face side, appears to have 2 rows of stitches  On the back side, the rows of stitches inter-loop  Strong and extensible, but unravel more easily than true safety stitch  Less costly, only one row of stitches

British Standard

 Subclass 503 (1 needle + 1 looper); Used for edging  Subclass 504 (1 needle + 2 loopers); Used for edging & light seaming  Subclass 514 (2 needles + 2 loopers); Used for edging & heavy seaming

American Standard - Combination Stitch

 Subclass 515 (401 + 503); Used for edging & sewing  Subclass 516 (401 + 504); Used for edging & sewing

Stitches: Class-503 (Sub-Classes)

Stitch Class 503 (overedge): Stitch formed by 1 needle thread and 1 looper thread forming a purl on the edge of the seam. For serging or blind hemming only.

Thread consumption ratio=1 : 10.5

This type of stitch is formed with 2 threads:

1 Needle thread (A) 1 Looper thread (B)

The loops of the needle thread (A) are passed through the material and brought to the edge where they are inter- looped with thread (B). The loops of thread (B) are extended from this inter-looping to the point of needle penetration of the next stitch and there are inter-looped with thread (A).

Stitch type 503

Stitches: Class-504 (Sub-Classes)

Stitch Class 504 (overedge): Stitch formed by 1 needle thread and 2 looper threads forming a purl on the edge of the seam. For overedge seaming and serging.

Thread consumption ratio=1 : 14

This type of stitch is formed with 3 threads:

Stitch type 504

1 Needle thread (A) 1 Lower looper thread (B) 1 Upper looper thread (C)

The loops of the needle thread (A) are passed through the material and inter-looped with loops of thread (B) at the point of penetration on the underside of the material. The loops of thread (B) are extended to the edge of the material and there inter-looped with loops of the upper looper thread (C).

Stitches: Class-505 (Sub-Classes)

Stitch Class 505 (overedge): Stitch formed by 1 needle thread and 2 looper threads forming a double purl on the edge of the seam. For serging only.

Thread consumption ratio=1 : 16

Stitch type 505 is very similar to stitch type 504. The main difference is that in stitch type 505 the lower looper thread (B) Is tighter and the needle thread (A) is looser than in stitch type 504. Stitch type 505 is a three thread version of stitch type 503.

This type of stitch is formed with 3 threads:

Stitch type 505

1 Needle thread (A) 1 Lower looper thread (B) 1 Upper looper thread (C)

The loops of the needle thread (A) are passed through the material and inter-looped with loops of thread (B) at the point of penetration on the underside of the material. The loops of thread (B) are extended to the edge of the material and there inter-looped with loops of the upper looper thread (C). The loops of thread (C) are extended from this inter-looping point of the needle penetration of the next stitch and there, they are inter-looped with thread (A).

Stitches: Class-512 (Sub-Classes)

Stitch Class 512 (overedge): Stitch formed with 2 needle threads and 2 looper threads with the looper threads forming a purl on the edge of the seam. In the 512 stitch, the right needle only enters the upper looper loop. This stitch type will not chain-off as well as the 514 stitch.

Thread consumption ratio=1 : 16

This type of stitch is formed with 4 threads:

2 Needle threads (A & A1) 1 Lower looper thread (B) 1 Upper looper thread (C)

Stitch type 512

The loops of the needle threads (A & A1) are passed through the material and inter-looped with loops of thread (B) at the point of penetration on the underside of the material. The loops of thread (B) are extended to the edge of the material and there inter-looped with loops of thread (C). The loops of thread (C) are extended from this inter-looping point of the needle penetration of the next stitch and there, inter- looped with thread (A).

Stitches: Class-514 (Sub-Classes)

Stitch Class 514 (overedge): Stitch formed with 2 needle threads and 2 looper threads with the looper threads forming a purl on the edge of the seam. In the 514 stitch, both needles enter the upper looper loop. Preferred over the 512 Stitch because it chains-off better.

Thread consumption ratio=1 : 20

This type of stitch is formed with 4 threads:

2 Needle threads (A & A1) 1 Lower looper thread (B) 1 Upper looper thread (C)

The loops of the needle threads (A & A1) are passed through the material and inter-looped with loops of thread (B) at the point of penetration on the underside of the material. The loops of thread (B) are extended to the edge of the material and there inter-looped with loops of thread (C). The loops of thread (C) are extended from this inter-looping point of the needle penetration of the next stitch and there, inter-looped with threads (A & A1).

Stitch type 514

Stitches: Class-515 (Sub-Classes)

Combination Stitch

Stitch Class 515 (overedge): This type of stitch is formed by simultaneously sewing a single needle chainstitch (401) and a 2 thread overedge stitch (503). Using threads (A & B), at a specified distance from the edge of the material, and one row of stitch type 503 using threads (A1 & B1) on the edge of the material.

Uses less thread than a 516 stitch; however, many manufacturers prefer a 516 stitch.

Thread consumption ratio=1 : 17.5

Stitch type 515

Stitches: Class-516 (Sub-Classes)

Combination Stitch

Stitch Class 516 (safety stitch): This is a 5-thread safety stitch formed by simultaneously sewing a single-needle chainstitch (401) and a 3-thread overedge stitch (504).

Thread consumption ratio=1 : 20

Stitch type 516

Stitches: Class-600 (Cover stitch)

Class-600 (cover stitch): The stitches under this class are generally produced with three groups of threads. Threads of two groups can be seen from either side. The first group of threads are called needle threads, the second are called top cover threads and the third are called bottom cover threads. The stitches of this class are very complex and up to 9 threads can be used in producing these stitches.  Also called: Flat seam stitches, interlock stitches, flatlock stitches  Cover stitches sew flat seams in which fabric piles about or overlap slightly and are interlocked by the stitches  "Web of threads" appear on both face and back of the flat seam

Applications: •

Knits, lingerie, binging elastics, etc..

Decorative

•

Advantages: •

Create strong very extensible stitches

• The many inter loopings finish the raw edge of the fabric • Require little or no seam allowance, conserves fabric • 605 is the most common in 600 class

Disadvantages: •

Uses a lot of thread

• Can be uncomfortable if soft thread not used • More suitable for knits than woven garments

Stitches: Class-602 (Sub-Classes)

Stitch Class 602 (coverstitch): Stitch is formed with 2-needle threads, a top cover thread and a bottom looper thread.

Thread consumption ratio=1 : 20.0

This type of stitch is formed with 4 threads:

2 Needle threads (A) & (A1) 1 Looper thread (B) 1 Cover thread (C)

The loops of thread (A) and (A1) are passed through loops of thread (C) already cast on the surface of the material, and then through the material where they are inter looped with loops of thread (B) on the underside.

Stitch type 602

Stitches: Class-605 (Sub-Classes)

Stitch Class 605 (coverstitch): Stitch is formed with 3-needle threads, a top cover thread and a bottom looper thread.

Thread consumption ratio=1 : 27.0

This type of stitch is formed with 5 threads:

3 Needle threads (A), (A1) & (A2) 1 Looper thread (B) 1 Cover thread (C).

Stitch type 605

The loops of thread (A), (A1) and (A2) are passed through loops of thread (C) already cast on the surface of the material, and then through the material where they are inter looped with loops of thread (B) on the underside.

Stitches: Class-607 (Sub-Classes)

Stitch Class 607 ( coverstitch): Stitch is formed with 4-needle threads, a top cover thread and a bottom looper thread. Preferred over 606 stitch because the machines are easier to maintain.

Thread consumption ratio=1 : 27.4

This type of stitch is formed with 6 threads:

4 Needle threads (A), (A1), (A2), and (A3) 1 Looper thread (B) 1 Cover thread (C).

Stitch type 607

The loops of thread (A), (A1), (A2), and (A3) are passed through loops of thread (C) already cast on the surface of the material, and then through the material where they are inter looped with loops of thread (B) on the underside.

Underside

Face Side

SPI (Stitches per inch) – What you should know When writing garment specifications, you should not neglect specifying the proper number of stitches per inch that should be used in your sewn products. Why? Because the number of stitches per inch can have a direct influence on the following: 1) the seam strength; 2) the stitch appearance; and 3) the seam elasticity on stretch fabrics.

An estimated seam strength formula was developed years ago for woven seams where one piece of fabric is placed on top of another with a specific seam margin and stitched with either a 301 lockstitch or 401 chainstitch.

Obviously, the seam strength is dependent on a number of factors including: • Type & Weight of the Fabric • Stitch & Seam Construction • Stitches Per Inch • Thread Type and Size • Stitch Balance (Thread Tensioning)

Formula for Estimating Seam Strength on Woven Fabrics

301 Lockstitch - Estimated Seam Strength = SPI X Thread Strength (lbs.) X 1.5* * 1.5 is a factor based on the average loop strength ratio of most sewing threads.

= 10 SPI X 4.0 lbs. X 1.5 = 60 lb. strength

401 Chainstitch – Estimated Seam Strength = SPI X Thread Strength (lbs.) X 1.7*

* This factor is higher than a lockstitch because +/- twice as much thread is consumed per inch of seam using a chainstitch. = 10 SPI X 4.0 lbs. X 1.7 = 68 lb. strength

From this formula, you can see the impact that stitches per inch, thread strength and stitch selection have on the strength of the seam. Generally, the more stitches per inch, the greater the seam strength. There are rare cases where adding stitches per inch can actually damage the fabric so that the seam is weakened, however, this only happens on specific fabrics that can be damaged by excessive needle penetrations.

SPI (Stitches per inch) – What you should know

Given: - 301 Lockstitch Superimposed Seam - Thread Used Top & Bottom = T-24 Perma Core – Strength: 2.6 lbs.

SPI

6

8

10

12

Estimated Seam

23.4 lbs.

31.2 lbs.

39 lbs.

46.8 lbs.

Strength

As you can see from the chart above, the stitches per inch has a tremendous impact on the strength of the seam, as long as the fabric doesn’t rupture before the thread. If the same seams were sewn with a lower tenacity spun polyester thread, this also will effect the resulting seam strength.

Given: - 301 Lockstitch Superimposed Seam - Thread Used Top & Bottom = T-27 Spun Poly – Strength: 2.2 lbs.

SPI

6

8

10

12

Estimated Seam

20 lbs.

26 lbs.

33 lbs.

40 lbs.

Strength

Some manufacturers substitute a smaller bobbin thread when sewing lockstitch seams to minimize the number of times it takes the sewing operator to change the bobbin. Remember, however, that the resulting seam strength will be much less and will be determined by the strength of the bobbin thread and not the needle thread. How to Measure the Stitch Length or Stitches Per Inch? The stitch length is measured by measuring the number of lengths of thread found within one inch. Stitch counters are available and make this measurement easier, however, you can place a ruler next to the seam and perform the same task.

SPI is measured by counting the number of lengths of thread found within one inch. As you can see here, there are approximately 9 SPI sewn in this seam.

SPI (Stitches per inch) – What you should know

SPI Recommendations for Wovens & Knits

Below is a list of garments and the typical number of Stitches Per Inch recommended for each of them. WOVEN GARMENTS

Garments

SPI

Comments

Garments

SPI

Comments

Denim Jeans, Jackets, Skirts

7-8

Fewer stitches per inch generally will give a more contrast stitch appearance.

Children's Wear

8-10

Usually 8 to 10 SPI is adequate to provide adequate seam strength and at the same time allow for quicker cycle times. Due to many of the operations being lockstitch, usually 10 -12 SPI is required to provide adequate seam strength. A long stitch length is desirable to minimize the dimple or appearance of the needle penetration on the outside of the garment. Buttonsew machines are cycle machines with a predetermined number of stitches per cycle.

Twill Pants or Shorts

8-10

More stitches per inch will help minimize seam grinning.

Dresses, Skirts

10-12

Trousers, Dress Pants, Slacks

10-12

On some operations like serge panels, it may be desirable to use a longer stitch length.

Blindstitch operations on Slacks, Dresses, Skirts, etc..

3-5

Dress Shirt or Blouses

14-20

Using more SPI allows the use of smaller diameter threads that will minimize seam puckering. Using more SPI will give more of a tailored stitch appearance and better seam coverage when serging.

Buttonsew (4 hole buttons)

16

Casual Shirts, Blouses, Tops

10-14

Buttonhole (1/2” purl or whip stitch)

85-90

Generally sewn vertically – approx. 85-90 stitches with a lockstitch buttonhole machine.

SPI (Stitches per inch) – What you should know When setting standards for stitches per inch, you should always keep in mind that more stitches per inch required in a seam, the longer the sewing cycles to complete the seam. Longer sewing cycles translates into higher labor costs and lower production levels. A sewing machine sewing at 5,000 SPM (stitches per minute) at 8 SPI will sew 17.4 yards of seam per minute. A sewing machine sewing at 5,000 SPM at 14 SPI will sew 9.9 yards of seam per minute.

More stitches per inch will also consume more thread per inch of seam. This will contribute to higher seam strength and more elastic seams, but will also increase the consumption of thread required to sew the garment.

Therefore, the recommendations listed above are common stitch levels that provide adequate seam strength but also take into consideration the factors just mentioned. When sewing knit fabrics, you should always check for excessive “seam grinning” of the seam and also check for “stitch cracking”. “Seam grinning” occurs when thread stitch balance is too loose allowing the seam to open up too much when stress is applied to it. “Stitch Cracking” is checked by applying pressure on the seam in the stitching direction. If the thread tensions are too tight or if you are not using enough stitches per inch, the threads will rupture as stress is applied on the seam. Therefore, the following recommendations have been made for the number of stitches per inch to be used on the following garments.

KNIT GARMENTS

Garments

SPI

Comments

Garments

SPI

Comments

Jersey T-shirts, Tops, Polos

10-12

Using more SPI increases the chance of needle cutting.

Swimwear

12-16

The more elastic the seam, the more SPI that should be used to minimize stitch cracking. The more elastic the seam, the more SPI that should be used to minimize stitch cracking. The more elastic the seam, the more SPI that should be used to minimize stitch cracking.

Underwear

12-14

The more elastic the seam, the more SPI that should be used to minimize stitch cracking. The more elastic the seam, the more SPI that should be used to minimize stitch cracking.

Dresses, Skirts

10-12

Infant Wear

10-12

Intimates

12-16

Knit Garments continued on next page.

SPI (Stitches per inch) – What you should know

KNIT GARMENTS continued

Garments

SPI

Comments

Garments

SPI

Comments

Fleece

10-12

More stitches per inch are required to provide the proper seam coverage on fleece. The more elastic the seam, the more SPI that should be used to minimize stitch cracking.

Stretch Knits (Lycra®, Spandex®, etc..)

14-18

More stitches per inch are required to provide the proper seam elasticity. Usually sewn with very fine thread. More SPI are required to minimize seam grinning and seam elasticity.

Sweaters (Medium - Heavy)

8-10

Hosiery, Socks

35-50

From the comments and information listed above, you can see how important it can be to add specifications instructions for Stitches Per Inch to your garment. Using the correct number of stitches per inch can greatly enhance the strength, appearance and performance of the seam for a given fabric type and application.

Courtesy of A&E

Sewing stitch terminology

Stitch length:

Measured in terms of the number of Stitches Per Inch. The longer that stitch, the further a sewing machine can sew in the same amount of time (10 SPI faster than 20 SPI).

Lengthening stitches:

Lengthening stitches is an easy way for manufacturers to cut costs.

Stitch tension:

Refers to how loosely or tightly the threads are held by the sewing machine as it sews.

Balanced tension:

Equal tension on needle, bobbin, and/or looper threads.

Lockstitch tension:

Affected by unbalanced tension more than other stitch types. Unbalanced lockstitch tensions causes the

Most affected by tension

fabric to pucker. Balanced tension is crucial for durable lockstitches.

Short stitch advantages:

Contributes to increased stitch strength and durability. Stitches too long or too short may lead to puckering. Short stitches make smaller ruptures in rows of stitches when they break than long stitches.

Less

apt to cause seam grin/tighter seam. Allows the seam to be more extensible.

Needle cutting:

Results when the needle cuts or severs the threads of the fabric rather than slipping between them. CAUSED BY: Too large a needle for fabric type, blunt or damaged needle or wrong type of needle tip.

Needle heating:

Occurs when sewing friction heats the needle. Fuses or melts the finishes or fibers of the thread of fabric. Fast sewing speeds are the main cause of needle heating.

Needle chewing:

Results in jagged, enlarged needle holes in the fabric.

Back tacking:

Secures the stitches, and prevents unraveling. A sign of high quality. Done automatically by industrial sewing machines. 500 and 600 class stitch machines are not capable of back tacking.

Latch tacking:

Draws the excess thread chain at the beginning of each row of stitches into the stitches to secure them. Used for 500 and 600 class stitches.

Acknowledgment

Southeast University – Department of Textile Engineering –by Mazadul Hasan Sheshir © www.textilelab.blogspot.com

Coats - Images www.coats.com

A&E – Stitch Terminology Glossary www.amefird.com/technical-tools/thread-education/glossary/stitch-terminology-glossary/

Yarn Manufacturing Technology www.facebook.com/pages/Yarn-Manufacturing-Technology/485014954866808

Fabric Manufacturing Technology www.facebook.com/pages/Fabric-Manufacturing-Technology/459520217425605

Garments Manufacturing Technology www.facebook.com/pages/Garments-Manufacturing-Technology/472364799463126

Wet processing Technology www.facebook.com/pages/Wet-Processing-Technology-Dyeing-/468645219825404

Fashion-Design-and-Technology www.facebook.com/pages/Fashion-Design-and-Technology/587655294583875?ref=ts&fref=ts