Output
Hourly output is cavities times shots per hour. A 15-second cycle is 240 shots an hour, so each extra cavity adds 240 preforms an hour before downtime.
Engineering guide
How to choose a PET preform mold cavity count.
Cavity count sets hourly output, the injection machine and the mold price. The figures below come from published OSLON projects and from the cavity calculator. They are not a recommendation for your preform until the drawing is reviewed.
Four checks
Output, shot, platen, then flexibility.
Shot weight
Multiply preform weight by cavities. The machine's PET shot has to cover that with a working margin. A screw that can hold the shot but melts it slowly will stretch the cycle.
Platen
Each cavity needs room for the neck ring, cooling and a hot runner nozzle. Compare mold length and width with the tie bars, and check mold height and opening stroke.
Flexibility
One high-cavity mold uses less floor space. Two medium molds can run two preform weights and keep one machine up if the other stops. There is no single right count.
The longer explanation, including the cost trade-off, is in the cavity-count article. This page is the specification path into a quotation.
Worked examples
Two published cycles, not a catalog.
Both are 14 g mineral-water preforms. The longer cycle on the larger mold produces fewer preforms per hour.
| Mold | Machine | Cycle | Preforms per hour |
|---|---|---|---|
| 64 cavity | Yizumi 320T | 12 s | 19,200 |
| 72 cavity | Yizumi 480T | 15 s | 17,280 |
Platen planning
Typical layouts for neck finishes up to 30 mm.
Taken from the cavity calculator. A 38 mm or 48 mm neck needs a wider pitch, so the mold grows even when the cavity count stays the same. These sizes are not the drawings of the photographed molds.
| Cavities | Arrangement | Pitch | Mold size |
|---|---|---|---|
| 16 | 2 × 8 | 60 × 160 mm | 750 × 440 mm |
| 24 | 4 × 6 | 60 × 140 mm | 780 × 555 mm |
| 32 | 4 × 8 | 55 × 130 mm | 810 × 520 mm |
| 48 | 4 × 12 | 50 × 130 mm | 930 × 560 mm |
| 64 | 4 × 16 | 50 × 130 mm | 1,000 × 650 mm |
| 72 | 6 × 12 | 50 × 130 mm | 1,120 × 690 mm |
| 96 | 6 × 16 | 50 × 130 mm | 1,260 × 850 mm |
Questions
Cavity count, in short.
How do you turn a cavity count into preforms per hour?
Preforms per hour equals cavities × 3,600 ÷ cycle time in seconds, before downtime. A published 64-cavity mold at a 12-second target is 19,200 preforms an hour. A published 72-cavity mold at a 15-second target is 17,280. Colour changes and maintenance take hours out of the year, so size the mold for real demand.
Does more cavities always mean more output?
No. The 72-cavity record above makes fewer preforms per hour than the 64-cavity record because the target cycle is longer. Shot weight and plasticising rate can erase the gain as well. 72 cavities of a 14 g preform is 1,008 g of PET per shot.
Will 48 cavities fit my machine?
For neck finishes up to 30 mm, the calculator's typical 48-cavity layout is 4 × 12, pitch 50 × 130 mm, mold size 930 × 560 mm. Compare that with tie-bar distance, mold height and opening stroke. A larger neck makes the same cavity count a larger mold. The calculator checks a specific machine. It does not estimate cycle time.
Where are the full project records?
The 64- and 72-cavity case pages publish neck, weight, machine, cycle and steel. The 48 cavity page publishes the mold photograph and a runner layout, and it labels the missing fields. Customer names are not published on any of them.
Start with confirmed project data