Bottle cap mould: how many cavities and what to specify before you order
Cavity count on a bottle cap mould is an output decision. It stays incomplete until you name the closure, the neck it must fit, and the cycle you can hold. The photographs on this site are a 24-cavity front view and a 32-cavity cap mould. They show the tooling. They do not show the resin, the finish, the cycle or the steel. Settle the points below before two quotations can be compared on price.
Closures per hour are cavities times shots
A cap mould makes one closure per cavity on every shot that fills. Hourly output is the cavity count multiplied by the shots you run.
Closures per hour = cavities × 3,600 ÷ cycle time in seconds.
"32 cavity" fixes the closures per shot and leaves the hour open. An hourly target leaves the cavity count open until a cycle for this closure is agreed. Either line on its own is an unfinished specification.
The cap mould page shows a 24-cavity front view and a 32-cavity mould. Resin, wall, seal, tamper band and cycle are not in those photographs, so the numbers are project records, not a catalogue. Put a cycle you have timed on your press next to the cavity count, or send the good closures you need in an hour and agree the cycle at the trial.
Bottle cap and closure molds, including the published photographs
A published preform cycle is the wrong number to paste onto a closure. The 64-cavity record is a 14 g, 29/25 mineral-water preform on a Yizumi 320T, 12-second target, 19,200 preforms an hour. The 72-cavity record is a 14 g, 30/25 preform on a Yizumi 480T, 15-second target, 17,280 preforms an hour. Both gate into the preform base. Those seconds stay with those preforms.
64-cavity preform project record
72-cavity preform project record
- Colour changes. Say how many you run in a day. Output stops while the colour is purged.
- A stopped cavity. A damaged tamper-band component or a blocked cavity removes that share of every shot.
- Sealed parts. Flash on the sealing face, a short shot or an oval skirt is scrap. An uninterrupted 24-hour figure is only a ceiling.
Match the closure to the neck and the capper
The neck finish is cut in the preform mould, and blow moulding does not change it. The closure has to screw on, seal, and fit the capping chucks already in the plant. Settle the finish before you settle the cavity count.
PCO 1881 and PCO 1810 are both 28 mm finishes. PCO 1881 is shorter, and the closures do not interchange: a PCO 1881 bottle needs a PCO 1881 closure. 26/22, 29/25 and 30/25 are lighter finishes used on mineral water. The published 64-cavity preform is 29/25. The published 72-cavity preform is 30/25. A cap mould cut for one of those finishes will not close the other.
A finish change means a different closure, new neck rings in the preform mould, and a check of the blow moulds and the capping heads. If the chucks are already cut for one finish, write that finish into the cap specification.
- Which closure you will mould, or which one you can buy for the markets you fill.
- Whether the product is still, carbonated or hot-filled. The seal and the neck follow that.
- Whether the same bottle will be sold with more than one closure standard.
The neck-finish guide compares these finishes, including why a move from PCO 1810 to PCO 1881 is a new closure. Name that finish on both the preform mould and the cap mould before either tool is cut.
PCO 1881, PCO 1810 and the water neck finishes
What to put in the drawing package
Two offers can both say "32-cavity cap mould" and still be different tools. Send what you know, and leave a blank where you do not. A guessed resin or a guessed cycle, written down as a decision, gets cut into steel.
| Item | Write this | If the line is blank |
|---|---|---|
| Closure | Drawing or a sample: outside diameter, height, thread and the seal | There is no part to cut |
| Neck finish | PCO 1881, PCO 1810, 26/22, 29/25, 30/25, or your preform drawing | Cap and preform can disagree |
| Band and liner | Tamper band or not, and whether a liner is fitted | Seal and ejection stay open |
| Resin | PP, HDPE, or the grade you run, plus colour, if known | Shrinkage and flow stay open |
| Output | Cavity count with a cycle, or good closures per hour | Output and cavity count stay separate |
| Press | Brand and model, or tonnage and tie-bar distance | Fit on the press is unknown |
| Gate | Hot runner or not, and surfaces that must stay free of a gate mark | Gate position stays open |
| Changes | How often the colour changes, and how many closures share the mould | Purge time is missing |
Add an opening torque only if you already have a target. None is published here to copy. Steel, cycle and price wait until the drawing and the machine are known. If the preform mould is in the same project, send both drawings together. "About 28 mm" is not a neck finish.
A cap gate is not a preform gate
A PET preform is gated in the base. Valve gate and open gate, for that base, are compared in a separate guide. Use it for a preform mould. It is the wrong gate instruction for a closure.
Valve gate or open gate on a preform mould
A cap mould gates into the closure, sometimes near a sealing face, and the part is ejected differently. The 24- and 32-cavity photographs do not show a gate, so no gate type is named here. Say which surface a vestige may mark. A mark on the sealing face can leak while the thread still gauges. A mark on the top panel is an appearance limit.
Ask how the thread is released, and how the tamper band, if the drawing has one, clears the steel without tearing or pulling the skirt oval. Say whether the closures drop free or a robot takes them. Take-out cooling from a preform line is not assumed.
"Stack" on a quotation means more than one parting face. The published cap photographs are not described as stack tools. If you need that construction, send the opening stroke and ask how many faces are priced and which spares repeat.
The cavity calculator checks preform cavity count against platen drawings for neck finishes on file. It does not lay out a cap mould, and it does not estimate a closure cycle.
Name the steel, the cooling and the spares
Name the steel by component: plates, cavity inserts, cores, the pieces that form the thread and the tamper band, and the gate inserts. One grade for the whole tool is not a specification. Ask for a line on each component, and for a document you can check when the steel arrives.
The published preform cases record 4Cr13H on the base and S636 on the cores and cavities. Those names belong to those preform tools. The cap photographs carry no grade, so none is assigned here. The preform steel guide is the method: a component list, and the cooling conditions beside any cycle. It is not a grade list to copy onto a closure.
How preform projects name steel and cooling
If you need a certificate or a hardness check, name that method in the order. No hardness figure and no shot life are published here. Shot life depends on the resin, the colourant, alignment, water and maintenance.
Ask which circuits cool the cores, the cavities and the steel around the seal, and whether they can be flushed. A long series circuit can leave the last cavities warmer, so weight drifts across the shot. Ask for the cooling diagram before machining.
Name the spares in the order: heaters and thermocouples if there is a hot runner, plus gate inserts and tamper-band components when the design uses them. Leave valve pins off the list unless this closure actually has them. Every mould is covered for 2 years after delivery, and the spare list still defines the crate.
Moulds from this Taizhou factory already run in Thailand, Vietnam, Indonesia, Malaysia and India, among other countries. Say if the shop is humid or the water leaves scale. That is a question about plates and channels, not a grade.
What to accept before shipment
Put the acceptance criteria in the order before the trial: drawing and tolerances, the cycle you will accept, the machine, and how many shots are checked.
The preform checklist is the right list for a preform. It includes neck gauges and, on the 64-cavity record, a weight of 14 g ±0.2 g. Use a gram tolerance on a closure only when the closure drawing states one.
Preform mould acceptance checklist
- Weight of every cavity against the tolerance in the order.
- Thread, outside diameter, height and the sealing face.
- The tamper band, when the drawing has one: in place, not torn, with any bridges the drawing shows still intact.
- Short shot, flash on the seal, a gate mark on a surface you did not accept, streaks and contamination.
- One full shot with cavity numbers marked, so one bad closure points at one insert.
Confirm that every cooling circuit flows and does not leak. Where there is a hot runner, record each zone temperature with the accepted shot. Ship the assembly drawing, the cooling diagram, the trial report and the spare list. Drain the channels and protect the moulding faces before the case is closed.
What to send OSLON
OSLON Precision Mold builds cap moulds in the same Huangyan workshop as the PET preform moulds. The company was founded in 2008. The workshop is at No. 27 Maofeng Street, Xinqian Street, Huangyan District, Taizhou, Zhejiang, and the public floor area is more than 2,000 m². Review the layout before machining.
- Closure drawing or sample, and the neck finish if the cap must match a preform you already run.
- Resin, if you know it, and how often you change colour.
- Cavity count, or the good closures per hour you need to ship.
- Injection machine brand and model, or tonnage and tie-bar distance.
- Whether you want a hot runner, and which surfaces must stay free of a gate mark.
- Liner, tamper band, and whether the product is still, carbonated or hot-filled.
Send the package to Frank Deng on the inquiry form, and leave unknown lines blank. Technical questions are answered from Taizhou within 8 hours. A missing finish or a missing resin stays a question. It is not replaced with a catalogue default.
A separate guide lists factory-or-trader checks for preform orders. The same three still apply here: an address you can visit, machining you can see, and a trial before the balance is paid.
Send the closure drawing with your inquiry
Questions buyers ask
Are the 24-cavity and 32-cavity cap moulds a range I can order by number?
No. They are published photographs: a 24-cavity front view and a 32-cavity mould. Cavity count follows the closure drawing, the output you need to ship and the injection machine. Steel, cycle and price are confirmed after those are known.
Can one cap mould run both PCO 1881 and PCO 1810?
No. The closures are not interchangeable. A PCO 1881 bottle needs a PCO 1881 closure. Each finish needs its own closure, and the preform neck has to match that closure before either mould is cut.
Can I copy a PET preform hot runner onto a cap mould?
No. A preform gate sits in the base of the preform. A cap mould gates into the closure, sometimes near a sealing face, and the closure is ejected differently. The valve-gate and open-gate guide is about that preform choice. Send the closure drawing and ask where the gate will sit.
What if the resin is not chosen yet?
Say that it is not chosen. PP, HDPE or a named grade changes shrinkage and the way the cavities have to be fed. A quotation that assumes a resin you have not approved is not a basis for machining.
What should the trial show before shipment?
A run at the cycle written in the order, the weight and the fit dimensions of every cavity, a sealing face you will accept, and the tamper band in the condition the drawing describes when the closure has one. Keep a numbered full shot, the cooling diagram and the trial report.
Does the cavity calculator size a cap mould?
No. It checks preform cavity count against platen drawings for neck finishes on file. It does not lay out a closure mould and it does not estimate a closure cycle. Send the cap drawing and the press data instead.