What this guide covers
The key point: A zipper is not made with one kind of mould. The metal hardware — the slider body, the pull-tab and the base plate — is produced by zinc-alloy die-casting. The plastic parts — the top and bottom stops on nylon/plastic zippers, and the teeth of resin zippers — are produced by injection moulding. These need different machines and different tooling.
The two tooling families buyers confuse
Buyers often say "zipper mould" as if it were one item. In a real zipper factory, tooling splits into two families built around two different forming processes:
| Tooling family | Process | Raw material |
|---|---|---|
| Die-casting mould (die) | Molten metal injected into a steel die under pressure | Zinc alloy |
| Injection mould | Molten plastic injected into a steel mould | Plastic resin (e.g. POM) |
Mixing these up is the most common and most expensive mistake when sourcing zipper tooling — a die-casting die cannot make plastic stops, and an injection mould cannot make a zinc slider.
Which part is made by which process
| Zipper part | How it's made | Tooling needed |
|---|---|---|
| Slider body (the part you pull) | Zinc-alloy die-casting | Die-casting die |
| Pull-tab / puller | Zinc-alloy die-casting | Die-casting die |
| Base plate / crown | Zinc-alloy die-casting | Die-casting die |
| Top & bottom stops (nylon/plastic zippers) | Plastic injection moulding | Injection mould |
| Resin (plastic) zipper teeth | Plastic injection moulding onto the tape | Injection mould |
| Metal zipper teeth | Stamped/formed from wire and clamped on the tape | Stamping tooling (separate) |
| Nylon coil teeth | Coiled monofilament — not moulded | Coiling head (no mould) |
Die-casting moulds — sliders, pullers, base plates
The visible metal hardware of a zipper is zinc-alloy die-cast. Molten zinc alloy is forced under pressure into a precision steel die; when it cools, it forms the slider, pull-tab or base plate. Because these parts must look good and run smoothly for the life of the garment, the die has to be precisely machined and well finished.
What matters when you order a die-casting die:
- Precision of the cavity — a worn or rough cavity produces sliders that jam or feel gritty.
- Surface finish — affects how the plated slider looks and feels.
- Consistency across cavities — multi-cavity dies must produce identical parts.
Injection moulds — stops and resin teeth
The plastic parts of a zipper are injection-moulded. Molten plastic resin (commonly POM) is injected into a steel mould. On nylon and plastic zippers this forms the top and bottom stops; on resin (plastic) zippers it forms the teeth, moulded directly onto the tape. These are separate moulds run on separate machines — the teeth mould is not the stop mould, and open-end and closed-end stops use different moulds again.
What matters when you order an injection mould:
- Clean, burr-free parts — stops and teeth must not have flash that catches.
- Correct fit to the tape and chain — moulded stops have to lock the slider reliably.
- Material match — the resin grade should match the zipper's intended use.
What to check before ordering custom tooling
- Confirm the process first. Tell the supplier the exact part (slider, puller, stop, resin tooth) so they quote the right tooling — die-casting die or injection mould.
- Ask for sample parts produced from the new tooling before you accept it, not just photos of the mould.
- Confirm precision and inspection. Ask how the supplier measures and inspects the finished parts.
- Clarify lead time and revisions in writing before ordering.
- Buy from a factory that makes both the tooling and the machines, so the tooling is matched to your production line.
How Primo (Jeso) supplies tooling
For transparency, this guide is published by Jeso, the machinery brand of Wenzhou Primo Zipper Machine Co., Ltd — a direct factory since 1984. Evaluate any tooling supplier, including us, against the checklist above.
- Both tooling families — zinc die-casting dies for sliders, pullers and base plates, and injection moulds for stops and resin teeth.
- Matched to the machine line — tooling supplied alongside the nylon, metal and plastic zipper machines that run it.
- OEM/ODM — custom slider and pull-tab shapes for brand differentiation.
- Factory-direct support — sample parts before acceptance, plus installation and technical help, with sales in English, Russian and Spanish.
FAQ
- Is a zipper slider injection-moulded or die-cast?
- The slider body, pull-tab and base plate are zinc-alloy die-cast — molten zinc forced into a steel die. They are not injection-moulded.
- What parts of a zipper are injection-moulded?
- The plastic top and bottom stops on nylon/plastic zippers, and the teeth of resin (plastic) zippers, are injection-moulded from plastic resin such as POM.
- Do I need different tooling for metal, nylon and plastic zippers?
- Yes. Metal teeth are stamped from wire, nylon teeth are coiled, and resin teeth are injection-moulded — each needs its own process. Sliders for all of them are die-cast.
- Can one supplier provide both die-casting dies and injection moulds?
- A full-line zipper machinery factory can supply both, matched to your production equipment — which avoids fit problems between tooling and machines.