How Are Zippers Made? Inside the Factory, Step by Step

Most people use a zipper dozens of times a day without thinking about it — yet a single zipper is the product of two separate manufacturing streams and more than a dozen specialised machines. This guide walks through how zippers are made, from a roll of yarn to a finished, tested zipper, and explains why nylon, resin and metal zippers are each made differently. If you are planning to produce zippers yourself, every step below corresponds to a specific machine on a zipper making machine line.

The parts of a zipper

Before the process makes sense, it helps to name the parts. Every zipper is built from four elements:

• Tape — the two woven fabric strips the zipper is built on, usually polyester.
• Teeth (elements) — the interlocking parts down each edge. These are coiled, moulded or stamped depending on the zipper type.
• Slider — the piece you pull, which meshes or separates the teeth. It includes the slider body, the pull-tab and a base/separating plate.
• Stops — the top stops and bottom stop (or a pin-and-box on open-end zippers) that keep the slider on the chain.

The teeth and tape are made together as a continuous "chain." The slider is made separately. The two only meet near the end, at assembly.

Three types, three ways to make the teeth

The single biggest fork in zipper manufacturing is the teeth. The tape, dyeing, assembly and testing are broadly similar, but the way the teeth are formed defines the zipper:

For a fuller comparison of the equipment each type needs, see our guide to nylon vs metal vs plastic zipper machines.

Step 1 — Weaving the tape

Everything starts with the tape. Polyester yarn is warped and then woven into narrow, dense strips on a needle-loom-style tape weaving machine. The weave includes a thickened edge (the "stringer" edge) where the teeth will later sit, because that edge carries all the stress when the zipper is pulled. Resin zippers add a couple of extra preparation steps here — warping and tape ironing — so the tape arrives at the moulding machine perfectly flat and tensioned.

Step 2 — Forming the teeth

This is the heart of the process, and it is where the three types diverge.

Nylon zippers — coiling and sewing

Nylon teeth are not made one at a time. A single nylon monofilament is heated and wound around a forming pin into a continuous coil shaped like a row of teeth. A separate high-speed sewing machine then stitches that coil firmly onto the woven tape. Because the teeth are one continuous coil rather than separate pieces, nylon zippers are light, flexible and "self-healing" — the coil springs back into mesh after the slider passes. A nylon long-chain line therefore runs several machines back to back: tape weaving, coil forming, coil sewing, dyeing and winding.

Resin / plastic zippers — injection moulding

Resin (plastic) teeth are injection-moulded directly onto the tape. POM plastic granules — coloured in advance with a colour-mixing step — are melted and injected into a long-chain mould that forms each tooth onto both tape edges at once. The mould is the precision part here: it determines the tooth shape and pitch. Trimmed scrap from each shot is reclaimed by a crusher and blended back with fresh POM, so very little material is wasted. Resin teeth can be made bold and decorative, which is why they are popular on outerwear and bags.

Metal zippers — stamping from wire

Metal teeth are stamped and formed from a flat metal wire — typically a copper alloy or aluminium — then clamped onto the tape edge at a fixed pitch. Each tooth is a small Y-shape pressed to bite onto the fabric. Because the forming of the metal chain is a heavy upstream process, many zipper factories buy in the finished metal long-chain and concentrate on the downstream finishing — gapping, stops, sliders and cutting — which is where most metal-zipper customisation actually happens.

Step 3 — Dyeing and winding the chain

Once the teeth are on the tape, the continuous chain is dyed to the required colour (resin teeth are usually pre-coloured in the POM, while nylon and the tape are dyed as chain), then wound into long yardage on a winding machine. At this stage the product is "zipper chain by the metre" — not yet individual zippers. Chain is the form in which long zippers are sold and in which short zippers are stored before being cut to length.

Step 4 — Making the slider (die-casting)

While the chain is being made, the slider is produced on a completely separate line. The slider body, the pull-tab and the base plate are zinc-alloy die-cast: molten zinc alloy is forced under pressure into a hardened steel die, cooled, then trimmed and surface-finished. Metal sliders are usually electroplated afterwards — gold, silver, gunmetal, antique brass and so on — both for appearance and corrosion resistance.

This is a common misconception worth repeating: sliders are die-cast, not injection-moulded. Injection moulding is reserved for resin teeth and for plastic stops. The tooling is different too — sliders need die-casting dies, while plastic teeth and stops need injection moulds. We explain the difference in our zipper tooling guide.

Step 5 — Assembly: gapping, sliders and stops

Assembly turns chain plus sliders into finished zippers. Depending on whether the zipper is open-end (like a jacket, which separates fully) or closed-end (like a trouser fly or pocket), the line runs a different sequence, but the building blocks are:

• Gapping — teeth are removed at set intervals to create the spaces where stops and sliders will go.
• Slider mounting — a threading machine feeds the slider onto the chain. Standard pull-tabs and fancy shaped pulls use slightly different mounting machines.
• Stops — top and bottom stops are added so the slider cannot run off. Plastic stops are injection-moulded in place; metal stops are formed from wire; open-end zippers get a pin-and-box at the base so the two halves can separate and re-join.
• Open-end reinforcement — open-end zippers have the cut point reinforced (taped/film-bonded) and a hole punched for the pin-and-box.
• Cutting — finally the chain is cut to the finished length. Ultrasonic cutting is used where a clean, sealed cut edge is needed.

Step 6 — Quality testing

A zipper has to survive thousands of open–close cycles, so finished zippers are sampled and tested on dedicated equipment:

• Reciprocating / cycle test — opens and closes the zipper thousands of times to check durability.
• Tensile / cross-wise strength — pulls the closed chain apart to measure how much force the teeth hold.
• Slider smoothness (pull force) — measures how easily the slider runs, so the zipper is neither too loose nor too stiff.
• Pull-tab and slider-lock torque — checks the strength of the pull and the auto-lock mechanism.

These tests map to recognised standards for nylon, resin and metal zippers, which is how buyers can compare quality between suppliers on more than just price.

Who makes the machines?

Every step above — weaving, nylon coil forming, resin injection moulding, dyeing, gapping, slider mounting, stop fitting, cutting and testing — is performed by a dedicated machine. Building all of them, plus the die-casting dies and injection moulds and the sliders themselves, is the work of a full-line zipper machinery factory.

That is what we do. Jeso is the machinery brand of Wenzhou Primo Zipper Group, a direct factory since 1984 with five production bases, 600+ workers and four dedicated workshops — zipper machines, zipper production, sliders & pullers, and mould-making. We supply complete nylon and resin zipper lines, the full set of downstream finishing machines for nylon, resin and metal zippers, the die-casting and injection moulds, the sliders, and the testing equipment — all CE certified and shipped to 160+ countries with installation, operator training and lifetime technical support.

If you are evaluating making zippers in-house, the next steps are our complete zipper making machine buyer's guide and how to choose a zipper machine supplier.

FAQ

How are zippers made?

In two parallel streams. The tape is woven and the teeth are formed on it — nylon teeth are coiled and sewn, resin teeth are injection-moulded, metal teeth are stamped from wire. The slider is die-cast separately. The chain is then dyed, gapped, fitted with a slider and stops, cut to length and tested.

How are nylon zippers made?

A nylon monofilament is coiled into a continuous spiral of teeth and sewn onto the woven tape, then dyed, wound, cut, and fitted with a slider and stops. The coil construction makes nylon zippers flexible and self-healing.

Is a zipper slider injection-moulded or die-cast?

Die-cast. The slider body, pull-tab and base plate are zinc-alloy die-cast and then plated. Injection moulding is used only for resin teeth and plastic stops, not for the slider.

How are metal zipper teeth made?

They are stamped and formed from a flat metal wire — usually copper alloy or aluminium — and clamped onto the tape edge at a fixed pitch, then finished with metal stops and, for open-end styles, a pin-and-box.

How many machines does it take to make a zipper?

A complete line is 15–30 dedicated machines, depending on the zipper type and whether it is open-end or closed-end — not a single machine.