Types of Industrial Sewing Machines for Garments: Lockstitch, Overlock, Coverstitch and Chainstitch

Types of industrial sewing machines at a glance

ISO 4915 is the international standard that classifies stitch types with three-digit numbers; the first digit gives the stitch class. According to AMANN's summary based on ISO 4915, class 300 is lockstitch, class 400 chainstitch, class 500 overlock and class 600 coverstitch types; 406 and 407 therefore sit in the 400 class. Coats' technical bulletin likewise defines 301 as the lockstitch, the whole 500 class as overlock (edge wrapping) and the 600 class as coverstitch with a top cover thread. Machine families are shaped around these stitches.

A looper, in the table, is the element that interloops the thread it carries with another thread to form the stitch (Coats); the MEGEP modules use the same name. MEGEP is the Turkish Ministry of National Education's vocational training module series. Catalog names change from maker to maker: “1-needle overlock”, “safety stitching”, “top and bottom coverstitch”. In a quote or order, have the stitch number, thread count and needle count written next to the machine name.

If you receive a machine list or quote from a Turkish factory, these are the terms you will meet:

Lockstitch machines

A lockstitch machine sews stitch number 301. The upper (needle) thread forms a loop with the bobbin thread under the fabric, locking in the middle of the fabric (MEB MEGEP, Lockstitch on the Machine, 2007). Coats describes 301 as the most common stitch type. The MEGEP modules call the machine “DSM”. A machine operator joins the pieces on the lockstitch machine, sewing the 301 stitch.

Strengths and weaknesses

• Strength: It gives a tight, strong, low-bulk stitch. Both sides look the same (Coats; MEGEP).
• Weakness: It has low stretch. Because the bobbin is changed often, its productivity is lower than chainstitch (Coats).

That is why, where a knit needs to stretch, stitches with more stretch (overlock, chainstitch, coverstitch) are preferred. In MEGEP's T-shirt sewing plan, the lockstitch machine only attaches the sleeve and side seam allowances (operation 7). The same module also allows a 2 cm lockstitch seam at the hem if the fabric suits it.

Single needle, twin needle and feed system

According to Coats, the 301 stitch can also be sewn on multi-needle machines; the most common multi-needle layout is twin needle. Juki's 2026 catalog divides lockstitch machines into single-needle and twin-needle groups, and by feed system into bottom-feed, needle-feed and bottom plus variable top feed models. The maker states that the bottom plus variable top feed model prevents the top ply from slipping and gives a pucker-free seam even on materials that are hard to feed.

Bed shape is also a criterion. The MEGEP module separates flat-bed, high-bed, block-type, free-arm and cylinder-bed machines. Juki's catalog calls the models flat-bed and cylinder-bed.

Electronic equipment, motor and lubrication

The MEGEP module counts two groups by operating system. In the first, the operator does jobs such as starting, stopping and back-tacking. In the second, high-speed electronic machines have functions such as thread cutting and back-tacking programmed digitally; sewing starts when the pedal is pressed and the machine stops when the program ends.

Two motor types are common on industrial machines: the traditional clutch motor and the servo motor. Juki's catalog lists accessories separately for users of the two motors. A clutch motor keeps running while the power is on and is noisy; a servo motor is silent at rest and uses less electricity (Wikipedia; Fasanella, Fashion-Incubator). Juki also presents its servo-motor, direct-drive lockstitch model as energy saving. Lubrication is a selection criterion too. Juki says it offers the “semi-dry head” design, which needs no oil in the needle-bar area, to reduce defective products caused by oil stains.

Chainstitch machines

A chainstitch machine uses no bobbin. The needle thread is looped under the fabric with a looper; in the two-thread type the needle thread forms a loop with the second thread that the looper carries (MEGEP). The single-thread chainstitch (101) is mostly used for temporary stitching and can unravel from the end (Coats). The table below compares the two-thread 401 stitch with the lockstitch.

Sources: Coats; MEGEP.

Chainstitch is also common on multi-needle machines (Coats). Juki's 2026 catalog includes flat-bed twin-needle double chainstitch machines (with parallel and in-line needles) and feed-off-the-arm models. In the feed-off-the-arm series there are twin-needle models for light to medium fabric and three-needle models for heavy fabric. The maker says the three-needle MS-3580 is strong enough to feed 16-ply extra-heavy denim and recommends it for lap seams such as jeans inseams, denim jackets and work uniforms.

Overlock machines

An overlock machine loops over the edge and on most models trims the edge at the same time: a knife cuts and evens the fabric edge while the needles and loopers form the stitch. Instead of a bobbin it uses loopers fed from thread cones (MEGEP, Overlock; Wikipedia). MEGEP states that circular-knit fabrics are sewn on overlock machines; 4–5 thread machines are preferred because they also sew the safety stitch in addition to edge finishing.

Overlock by number of threads

Sources: Coats, Basic Stitch Types; MEGEP, Overlock.

MEGEP's T-shirt plan uses a 3 or 4 thread overlock for joining seams and a 3 thread overlock for finishing hems and sleeve openings. In Juki's catalog this family is divided into “single-needle overlock”, “twin-needle overlock” and “safety stitching” (2026). Check the model page for thread count and stitch number.

Differential feed, bed type and attachments

Knit fabric can stretch and wave as it passes through the machine. Differential feed means the front and rear feed dogs are adjusted independently of each other; with the right setting knits do not wave and thin fabric does not pucker (Emborado glossary). MEGEP's overlock module likewise shows that loose or taut seams and gathering are obtained with the differential setting. Catalogs give the ratio separately for gathering and stretching; for example, for the Juki MO-6900S series gathering is 1:2 and stretching 1:0.7.

A cylinder-bed overlock offers a small-diameter cylinder bed for sewing narrow tube-shaped parts such as sleeve openings (Juki MO-6900C). There are separate series for very heavy work: Juki presents the MO-6900G series with an extra-high-lift upper looper and a coarse-type feed dog for materials such as jeans, raised (brushed) fabric, mats and carpets. With attachments fitted to the same body, jobs such as gathering, rolling in tape and blind hemming can also be done (Juki MO-6700DA examples).

Coverstitch machines

A coverstitch does not wrap the fabric edge. According to MEGEP's coverstitch module (reçme in Turkish), the stitch forms when two or three needle threads are tied with the lower looper thread: as many parallel straight stitches as needles show on the face, and the covering stitch on the back. With a top cover thread (karyoka) attachment and thread, the face is covered too. A coverstitch is not used only on the edge; it can also be used in the inner areas of the fabric for joining and decoration (MEGEP, Coverstitch, 2010; Wikipedia, Coverstitch). MEGEP's T-shirt module describes the coverstitch as a finishing technique used for hems and sleeve openings of knit garments: the stitch shows as two rows on top and one below. Because the fabric will stretch somewhat, allowances are reduced according to the stretch ratio of the fabric. Coverstitch operators sew hems, sleeve openings, bands and elastic on this machine.

Coverstitch stitches: 406, 407, 602, 605, 607

• 406 and 407: 406 is sewn with two needles and one looper thread. According to Coats, its main use covers the hems of knit garments and attaching elastic or lace on underwear. 407 is the three-needle version.
• 602: The 406 with a top cover thread (called karyoka thread in MEGEP) added.
• 605: Sewn with five threads: three needles, one looper and one cover thread. According to Coats it has high stretch, gives a flat, comfortable look and is a common choice for stretch garments; it uses above-average thread.
• 607 (flatseam): Sewn with four needles, one looper and one top cover thread. According to Coats it has largely replaced the older 606 flatlock.

Coverstitch machine variants

In Juki's 2026 catalog, coverstitch machines are divided into flat-bed and cylinder-bed types. “Universal” types are offered for finishing T-shirt sleeve openings and hems and for sportswear and knit products; the “collarette” (band) attaching model is for attaching bands on underwear, briefs and knit products. The “elastic-lace attaching” model is offered for shorts, underwear and foundation products, and comes with a fabric trimmer on the right side. Needle count and needle gauge are given separately on the model page. MEGEP's coverstitch module also separates the machines by the job they do in a similar way: hem coverstitch, band coverstitch with a binder attachment, belt-loop coverstitch that prepares waistband loops, and elastic coverstitch with a right-hand knife.

Overlock or coverstitch?

What does “interlock” mean here?

Interlock is first the name of a knit fabric. On the machine side, some makers call machines in the coverstitch family “interlock”: the machines in Pegasus's “Coverstitch (Plain seaming)” product group are listed on the maker's page as “interlock stitch machines”, and the W3500P series was introduced in the trade press as a “flatbed interlock sewing machine” for sewing knit garments (Apparel Resources, 2014). If “interlock” (interlok in Turkish) appears in a listing or quote, ask whether it means the fabric or the machine; if it is a machine, have the ISO stitch number, needle count and thread count written down.

Buttonhole, button, bartack and automatic machines

These machines are single-purpose. The classification below is based on the headings in Juki's 2026 catalog.

In its men's pants module, MEGEP puts buttonhole, button-sewing and bartack machines next to the lockstitch industrial machine and the overlock in the sewing environment, and states that the reinforcement stitch at a pocket opening can be sewn on the bartack machine. Juki's bartack series has a belt-loop attaching variant, and its eyelet buttonhole models include buttonhole shapes that end in a bartack. Setting up and adjusting buttonhole and button-sewing automatic machines is the job of the buttonhole and button operator (ilik düğmeci).

Which machine for which product?

The table collects matches that appear directly in the sources. Real lines are split or merged depending on the style, the machine park and the line layout.

If you are setting up a workshop, first break the product into operations; operation times decide how many of which machine you need. For the operation sequence and an SMV (standard minute value) example of this method, see CMT cost per T-shirt in Turkey. For where sewing sits in the production flow, see the garment manufacturing process guide. If you are choosing a contract workshop, ask about its machine park within the criteria in how to choose a CMT workshop.

Checklist for choosing a machine

1. Write the operation and the stitch first. Instead of the machine name, give the operation, the stitch number, and the thread and needle count: “hem, 406, two needles”. Catalog names change from maker to maker.
2. Look at the stretch of the fabric. According to Coats, 301 has low stretch and 401 gives higher stretch; the stretch of the 504 and the 600 class stitches is high. MEGEP's T-shirt module asks for a trial seam on a piece of the fabric before sewing, for the sewn line to be stretched and observed, and for no gap in the seam line when the fabric is pulled.
3. Choose model and needle by fabric weight. Catalog models are divided into light, medium, heavy and extra-heavy fabric. MEGEP gives needle sizes (Nm) as follows: for wovens, 60–80 for fine fabric, 80–90 for medium and 90–120 or heavier for thick fabric; for knits, 60–80 for women's underwear, 65–90 for men's underwear and 60–100 for knit outerwear. Smaller numbers suit fine fabric.
4. Match the bed and feed system to the job. Look for a cylinder bed for tube-shaped parts such as sleeve openings, needle feed or bottom plus variable top feed for fabric that is hard to feed, and differential feed on overlocks for knits.
5. Ask about the lubrication type. Where oil stains are not acceptable, compare the price and maintenance of semi-dry or dry head options if they exist.
6. Compare the motor and automation. Besides the servo versus clutch motor difference, compare equipment such as thread trimmers and automatic presser-foot lift; these reduce operations the operator does by hand. MEGEP describes how, on automatic machines, pressing the back of the pedal with the heel stops the machine and cuts the thread.
7. Confirm the needle system and spare parts. According to MEGEP, every machine has a needle system and needle selection first looks for compatibility with the machine system. Even in one maker's 2026 catalog, systems differ by family (in Juki's: DBx1 for lockstitch, DCx27 for overlock, UY128GAS for coverstitch, DPx5 for buttonhole and bartack machines, DPx17 for heavy types). Check that consumables such as needles, loopers and presser feet are available; for suppliers, see textile machinery spare parts suppliers.
8. Decide on service and second-hand together. For service access, evaluate textile machinery repair companies. If you are considering a second-hand machine, make the service question part of the same decision; dealers are listed under used textile machinery.

Summary

Choose the machine by its stitch, not its name. Lockstitch (301) is for joining and attaching, chainstitch (401) for strong joining on heavy fabric, overlock (500 class) for edge finishing and joining knits, and coverstitch (400 and 600 class) for hems and attaching bands, while buttonhole, button-sewing and bartack machines are single-purpose complements. As of the date of this guide (October 2026), the catalog information rests on the versions the makers have published; model names and technical values change with updates, so check the current catalog before buying. For machine suppliers, see industrial sewing machine suppliers and used textile machinery in Turkey.