Sewing Machine Needles: Types, Parts, Size and Application

Sewing Machine Needles

The needle was one of humankind’s first tools. Over the millenia it developed from a simple craft item to the precision tool for modern sewing machines. The needle is the most important component of the sewing machine due to the fact that it carries and delivers the sewing thread to the sewing mechanism and must penetrate the fabric whilst minimizing damage to the material. The manner in which fabric is pierced by the needle during stitching has a direct impact on the strength of the seam as well as garment appearance. This article explores the different types, parts, sizes, and applications of sewing machine needles.

The purposes of the sewing machine needles are to,

• Make a hole in the fabric so that the sewing thread could pass through it to form a stitch without causing any damage to the fabric while doing so.
• To carry the needle thread through the fabric to form a loop. This is then taken up by the hook in a lockstitch machine or by means of the looper in chain stitch machines.
• Pass the needle thread through the loop created by the looper mechanism on a chain stitch machine.

Factors to Consider When Choosing a Needle:

The factors to be considered when selecting a needle are:

• Fabric type
• Fabric density
• Fabric composition
• Seam thickness
• Type of machine

If the needle is not changed regularly, it can cause major quality problems. The needle is subject to the most use of all the machine parts as it penetrates the material at speeds of 5000–6000 times per minute for lockstitch and 8000–10,000 times per minute for chain stitch. The friction caused by the needle penetrating the fabric causes extreme heating, with needle temperatures in excess of 250 °C.

When fabrics are stitched together, the impact from the needle as it penetrates the fabric can cause buckling and distortion of the yarns and the fibers. A smaller-diameter needle reduces the mechanical forces exerted on the yarns. The mechanical strain on the yarns increases if the needle is damaged, and can cause the fibers to rupture and hence reduce the seam strength significantly.

The following approaches can be used to help avoid problems caused by needles:

• Use a needle with the smallest possible diameter for the fabric and seam being sewn.
• Adapt the opening of the sewing plate to fit the needle size.
• Use a sewing thread with the correct diameter for the needle eye.
• Use the correct needle point for the type of fabric being sewn.
• Consider whether the type of seam being used to construct the garment could be changed, or use multiple seaming in order to divide the strain.

Component Parts of a Sewing Needle

The most important aspect of needle design is the needlepoint, because it has to penetrate the fabric, without causing any damage to the material. It is also the most diverse part of the needle due to the many different type of points used. These needle points are designed for sewing on many different fabric types and seams. An example of needlepoint designs and the component parts of the needle can be seen in Figure 1.

The different parts of a sewing needle are briefly described below.

Shank: It is the top portion of the needle, which positions inside the needle bar. It could be designed as cylindrical or have a flat side, based on the method of holding it on to the needle bar. It is the principal support of the entire needle and is larger in diameter than the remaining part of the needle to give the strength.

Shoulder: It is the part in-between the shank and the blade, with the blade forming the longest portion of the needle up to the needle eye.

Blade: It undergoes an enormous amount of friction from the fabric through which the needle passes. In case of needles specifically designed for high-speed sewing, the shoulder is normally extended into the upper part of the blade to give a thicker cross section. This arrangement of reinforced blade strengthens the needle and produces the enlarged hole in the fabric while the needle is at its lowest point, thus minimizing the friction between it and the material. On the other hand, the blade could be designed as a tapered one, reducing its diameter gradually from shank to tip to minimize the friction.

Long groove: It gives a shielding channel for the sewing thread while it is carried down into the fabric for stitch formation thus reducing the abrasion and friction with the fabric.

Short groove: It is located on the reverse side of the long groove, that is, towards the hook or looper; it extends slightly above and below the needle eye. It assists in the formation of the needle thread loop.

Eye: It is the hole or opening in the sewing needle, lengthened through the blade along the long and short grooves on the needle. The profile of inside part of the eye at the top is vital in reducing sewing thread damage and in producing a good loop formation.

Scarf: The scarf otherwise known as clearance cut is a nook across the whole face of the needle immediately above the needle eye. Its objective is to facilitate closer setting of the bobbin hook or looper to the needle so that the needle thread loop could be entered more easily by the point of the hook or looper.

Point: It is tapering portion of the needle created to give a better penetration of the needle on various kinds of fabric. It should be properly selected to prevent damage of the fabric to be sewn.

Tip: It is the ultimate end of the point, which combines with the point in defining the penetration performance of the needle.

Special Needles

Several over-edge and safety stitch sewing machines utilize curved needles instead of straight needles. These needles are costly though the life of the needle is lesser compared to straight needles. However, the sewing machines utilizing curved needles (Figure 2a) could achieve higher speeds than by using straight needles. Blind stitching machines also utilize needles that are curved, but the purpose here is to avoid penetration right through the fabric. Sewing machines (pick stitching machine) that imitate hand stitch (class 209) utilize a double-pointed sewing needle with an eye in the middle (Figure 2b), through which is threaded the short length of thread with which this machine sews.

Identification of Sewing Needle

Three parameters are generally used for the identification of sewing needles such as system, point and size.

System

It describes the elements of a needle to suit the sewing machine type. Based on the type of sewing machine and type of stitch, the needle is designed with variants in blade length, shank thickness, type of needle eye, etc. It is worthwhile to ensure with the sewing machine manufacturer for appropriateness of needle system to machine.

Point / Types of Sewing Needle According to Point

Needles used for woven and knitted fabrics are called cloth points. Cloth points are generally of two types: round points and ball points. In general, round points are meant for woven fabric and ball points are meant for knitted fabric. Cutting points are used for leather and other laminated materials.

A needle point is broadly categorized into two types:

1. Cutting or leather point needle
2. Round point needle – set or cloth points

1. Cutting Point Needles:
Cutting point sewing needles have spiky tips like blades and a wide range of cross-sectional profiles such as rounded, triangular, square and lens exist. They are normally used to sew highly dense and non-fabric based materials. Five universal kinds of cutting point sewing needles are shown in Figure 3, along with their profile of incision produced when used in a machine with the commonest threading direction.

The narrow wedge point needle: It cuts the material at right angles (90°) to the seam direction and permits to go for a high stitch density (SPI) while leaving adequate material between the needle holes to retain seam strength of material. On soft leather material, stitch densities as high as 12 per centimetre are achievable. It is the most frequently utilized cutting point needle for stitching uppers in the shoe industry.

The narrow reverse point needle: It produces cut that lies 45° to the seam direction, and produces a seam where the thread is turned to the left on the surface of the material. The narrow cross point needle: It makes a cut along the line of the seam and necessitates a longer stitch length. Heavy decorative seams could be made where thicker sewing threads are used at lower stitch densities, that is, longer stitch length.

Numerous kinds of other point types exist for the variety of leathers, seams, sewing machines and strength and appearance requirements that arise. This involves triangular cross sections for multi-directional sewing.

2. Cloth Point Needles:
These kinds of needles are used for sewing textile materials instead of the leather/sheet materials as in the case of cutting point needles. The points have a round cross section contrasting to the various cutting profiles of the cutting point needles and the tip at the end of the point can vary in profile to suit the particular material being sewn.

• The contour of the tip of the needle point which attains the deflection rather than penetration is a fine ball shape and the needle is called a light ball point needle which is utilized primarily for sewing knitted fabrics.
• The tip of the needle point which attains the penetration has the shape of a cone and is known as a set point needle which is utilized for sewing woven fabrics. Both ball and set point needles are available in a number of types, illustrated in Figure 4.

  

Slim set point (SPI): It is generally used for sewing denser woven fabrics and aids in achieving a straighter stitch which could minimize seam pucker. Generally used for heavy woven fabrics, coated fabrics and topstitching of collars and cuffs.

Medium set point needle: It is the general purpose needle in noproblem sewing situations. It is commonly used for sewing a range of woven fabrics and in many circumstances could be used for knitted fabrics also.

Set cloth point (R): It is generally utilized for sewing standard fabrics with regular seams.

Acute set point: This kind of needle is used while sewing very dense fabrics like shirting fabric and interlining in collars and cuffs, where a straight line of stitching is required.

Heavy set point: These needles are used for sewing buttons as the button can be deflected to some extent into the correct position; thus, the needle can pass through the holes.

Light ball point (SES): It can be used for sewing lightweight knitted fabric and densely woven material.

Medium ball point (SUK): It is utilized for sewing denim fabrics of medium to coarser weight and knits.

Heavy ball point (SKF): It is utilized for sewing heavier woven elastic materials as well as coarser knits.

Special ball point (SKL): It could be utilized for sewing heavy knits and coarse elastics.

Needle Size

The size of the needle is the diameter of the needle, which is decided based on fabric to be sewn. The needle size is normally expressed in two ways. One of the basic methods of representation is by a metric number (Nm). This system represents the diameter of the needle blade in hundredths of a millimetre measured just above the scarf area. For example, a needle size of Nm 100 is 1.0 millimetre in diameter as shown in Figure 5. Another standard needle sizing method is the Singer system, otherwise called the American system, which uses a number that represents a size.

Needles are offered in a wide range of sizes and the selection of needle size is based on the combination of fabric and sewing thread which is to be sewn. If the selected sewing needle is too small for the sewing thread size, the thread will not fit well into the long groove of the needle and will suffer from extreme abrasion. The use of too fine a needle while sewing heavy plies of fabric could lead to the deflection of the needle, which could influence the stitch loop pick up and cause slipped stitches or even needle breakage. Use of a larger sewing needle for the particular sewing thread resulted in poor control of the loop formation which could lead to slipped stitches.

Application of General Purpose Needles

The general purpose needles used in apparel manufacturing are given in below Table.

Application of Specialty Needles

The specialty needles used in garment manufacturing are given in below Table.

Surface Finishing of Sewing Needles

Sewing needles are normally made from steel and during their final manufacturing stage they are polished, specifically in the needle eye area. They are then electroplated using chromium or nickel to provide resistance to mechanical wear, corrosion resistance and reduction of friction during sewing. One of the main requirements of the surface finishing of needles is it should not pick up any elements of synthetic fabric or thread which could melt due to excessive heat generation. By considering this aspect, the chromium-plated sewing needles are superior compared to nickel-plated needles.

Needle Selection

Almost all major brands have some sort of ready reckoner for selecting the most appropriate needle point type for different standard fabric types. The logic to be followed for selection of the correct size is the lighter the fabric, the narrower the needle; however, due to continuous development of new fabric types (and continuous modification of point types by needle manufacturers), the process is often prone to error. All major needle brands offer to recommend the best point type and size of needle once a fabric sample is provided to them by the manufacturer. The selection of needle systems is a non-issue, as the machine catalogues always mention the needle system to be used for that machine and generally no other system would work.

Conclusion

Sewing machine needles are crucial components in textile and garment manufacturing, ensuring smooth and precise stitching. Understanding the different types, parts, and sizes of sewing machine needles allows for better sewing results, whether for home projects or industrial production. Choosing the right needle size and type is crucial for achieving professional results in sewing projects.

References

[1] Karthik, T., Ganesan, P., & Gopalakrishnan, D. (2016). Apparel Manufacturing Technology. In CRC Press eBooks. https://doi.org/10.1201/9781315367507

[2] Sinclair, R. (2015). Textiles and fashion : materials, design and technology. In Woodhead Publishing

[3] Garment Manufacturing Technology. (2015). In Elsevier eBooks. https://doi.org/10.1016/c2013-0-16494-x

[4] Textile and Clothing Design Technology. (2017). In CRC Press eBooks. https://doi.org/10.1201/9781315156163

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