DECISION TOOL
Calculateur de nombre de caries ISBM : De combien de caries avez-vous réellement besoin ?
Choosing 4 cavities when you need 8 caps your production at half capacity. Choosing 16 when you need 8 doubles your mould investment and adds changeover friction. This guide provides the formula, scenario calculations, and hidden cost framework to land on the right cavity count for your Korean production line.
TL;DR — Résumé rapide
Calculate cavity count using: Annual bottles = Cavities × (3600 / cycle time) × operating hours × uptime factor. For 5-50ml pharma vials target 12-16 cavities; 50-300ml cosmetic 6-12 cavities; 300-800ml beverage 4-8 cavities; 1-2L wide-mouth 2-4 cavities; 5L large format 1-2 cavities. Higher cavity counts reduce per-bottle cost but increase mould capital 30-50% and changeover time 40-60%. For multi-SKU portfolios, select cavity count matching your highest-volume SKU and accept lower efficiency on smaller runs rather than undersizing for the largest.
Dans ce guide
1. Why Cavity Count is the Hardest Decision
After you choose the machine platform and bottle design, cavity count becomes the final critical decision before purchase order. Unlike most ISBM procurement decisions where buyers default to vendor recommendations, cavity count requires the producer’s own input because it depends on production volume assumptions only the buyer can forecast accurately.
The asymmetric risk makes this decision uncomfortable. Undersized cavity count caps production capacity permanently and cannot be retrofitted without buying a second machine or new mould. Oversized cavity count inflates mould capital cost 30-50% and introduces changeover friction that hurts multi-SKU production efficiency. Neither error corrects cheaply.
Korean producers typically arrive at the cavity count conversation after six weeks of bottle design work and machine evaluation. At that point, the forecasting discipline has often lapsed because everyone assumes the numbers are already locked in. This is exactly when the most expensive selection errors happen. The framework below converts cavity count from intuition into measured calculation.
2. The Core Capacity Formula
Annual cavity count calculation uses four inputs: cavity number, cycle time, operating hours, and uptime factor. The output is annual bottle capacity. Work backward from your target annual volume to determine required cavity count.
CORE FORMULA
Annual Bottles = Cavities × (3,600 ÷ Cycle Time) × Operating Hours × Uptime Factor
Cycle time in seconds. Operating hours per year. Uptime factor 0.90-0.98.
Input Reference Values
| Input Parameter | Gamme coréenne typique | Notes |
|---|---|---|
| Cycle time (50-300ml bottle) | 9-12 seconds | Depends on wall thickness + resin |
| Cycle time (500-1000ml) | 11-14 seconds | Longer cooling for larger bottle |
| Cycle time (1-2L) | 14-18 seconds | Heavy wall + thermal mass |
| Cycle time (5L gallon) | 25-35 seconds | Large thermal mass, heavy clamping |
| Single shift (8 hr) | 2,000 hours/year | 250 days × 8 hours |
| Two-shift (16 hr) | 4,000 hours/year | 250 days × 16 hours |
| Three-shift / 24-7 | 6,000-7,500 hours/year | Depends on holiday / maintenance calendar |
| Uptime factor (Korean tier) | 0.95-0.98 | Includes changeover, maintenance, small stops |
Use conservative uptime assumptions for first-year calculations. Korean producers running mature production lines on full-servo platforms commonly achieve 0.97-0.98 uptime. New installations during commissioning typically run 0.90-0.93 until operator experience and parameter optimization stabilize. Understate rather than overstate capacity during procurement calculation.
3. Three Real Scenario Calculations
The following three scenarios demonstrate the cavity count calculation for common Korean production profiles. Each scenario applies the same core formula to show how inputs drive the cavity decision.
Scenario A: 1 Million Bottles per Year, Single Shift
EMERGING K-BEAUTY BRAND
Entrées : 100ml PETG cosmetic bottle, 11-second cycle, single 8-hour shift, 0.95 uptime factor, 1M annual bottle target
Calcul: 1,000,000 = Cavities × (3,600 ÷ 11) × 2,000 × 0.95
Solving: Cavities = 1,000,000 ÷ (327 × 2,000 × 0.95) = 1.6
Recommendation: 2-cavity mould on compact 4-station platform. Provides 25% capacity headroom for demand growth. HGY50-V3-EV precision platform ou HGY150-V4 4-station matches this scale.
Scenario B: 5 Million Bottles per Year, Two Shifts
MID-SIZE CONTRACT FILLER
Entrées : 250ml PET cosmetic bottle, 10-second cycle, two-shift operation (4,000 hours/year), 0.96 uptime factor, 5M annual target
Calcul: 5,000,000 = Cavities × (3,600 ÷ 10) × 4,000 × 0.96
Solving: Cavities = 5,000,000 ÷ (360 × 4,000 × 0.96) = 3.6
Recommendation: 4-cavity mould provides matched capacity with marginal headroom. 6-cavity provides 40% headroom for growth and downtime absorption. For AOKI 250 mould compatibility preservation, choose HGY200-V4-B platform.
Scenario C: 20 Million Bottles per Year, Three Shifts
LARGE BEVERAGE PRODUCER
Entrées : 500ml PET water bottle, 9.5-second cycle, 24-hour three-shift operation (7,000 hours/year), 0.97 uptime factor, 20M annual target
Calcul: 20,000,000 = Cavities × (3,600 ÷ 9.5) × 7,000 × 0.97
Solving: Cavities = 20,000,000 ÷ (379 × 7,000 × 0.97) = 7.8
Recommendation: 8-cavity mould on Quai à 4 stations HGY200-V4. For buffer capacity and double-row efficiency, consider HGY250-V4-B double-row for higher throughput in similar footprint.
4. Cavity Count by Bottle Volume
Bottle volume imposes physical constraints on maximum cavity count. Clamping force, injection capacity, and mould footprint all limit how many cavities fit on a given machine platform. The following table shows typical cavity count ranges by bottle volume family.
| Volume de la bouteille | Typical Cavity Range | Application |
|---|---|---|
| 5-50 ml | 12-16 cavity | Pharma vials, serum bottles |
| 50-150 ml | 8-12 cavity | Small cosmetic, pharma |
| 150-300 ml | 6-12 cavity | K-beauty standard, pharma syrup |
| 300-500 ml | 4-8 cavity | Beverage commodity, body lotion |
| 500-1,000 ml | 4-8 cavity | Beverage, household chemical |
| 1-1.5 L | 2 à 6 cavités | Large beverage, wide-mouth jars |
| 1.5-2 L | 2-4 cavity | Large beverage, food jars |
| 2-4 L | 1-2 cavity | Bulk food, large container |
| 5-6 L | 1-2 cavity | 5L water gallon, B2B hospitality |
These ranges reflect practical production configurations. Theoretical maximum cavity counts can exceed the ranges shown, but practical cavity count is constrained by three factors: preform weight affecting injection clamping force requirements, bottle body dimensions affecting blow mould footprint, and cooling capacity affecting cycle time consistency across all cavities.
5. Ever-Power Platform Matching
Platform selection and cavity count must match. The following matrix identifies the maximum cavity count supported by each Ever-Power platform and the typical sweet spot for production efficiency.
| Platform | Max Cavities | Volume de la bouteille |
|---|---|---|
| HGY50-V3-EV | Up to 16 | 5-50ml pharma vials |
| HGY150-V4 | Up to 12 | 50-300ml cosmetic, pharma |
| HGY150-V4-EV | Up to 12 | Premium PETG, K-beauty |
| HGY200-V4 | Up to 8 | 300-800ml beverage |
| HGY200-V4-B | Up to 8 | AOKI 250 format, 250ml |
| HGY250-V4 | Up to 6 | 500ml-1.5L wide-mouth |
| HGY250-V4-B | Up to 12 (double-row) | High-throughput 1-2L |
| HGY650-V4 | Up to 2 | 5L water gallon, large format |
| EP-HGYS280-V6 | Up to 8 (6-station) | Complex asymmetric premium |
The double-row HGY250-V4-B deserves special note. Its architecture delivers up to 12 cavities in similar footprint to standard 6-cavity single-row platforms, effectively doubling throughput density for 1-2L bottle applications without requiring additional floor space or a second machine.
6. Hidden Costs of Higher Cavity Count
Higher cavity count reduces per-bottle production cost through economies of scale, but introduces hidden costs that are often underestimated during procurement. Korean producers should factor these costs into cavity decision.
Mould Capital Cost Scaling
Mould capital cost does not scale linearly with cavity count. Each additional cavity adds roughly 40-60% of the single-cavity cost due to shared infrastructure (base plates, hot runner manifold, cooling circuits). Typical Korean market pricing for 250ml cosmetic bottle moulds:
- ▸2-cavity mould: 40-60M KRW
- ▸4-cavity mould: 80-120M KRW
- ▸6-cavity mould: 120-180M KRW
- ▸8-cavity mould: 180-260M KRW
- ▸12-cavity mould: 280-400M KRW
These figures apply to custom-designed moulds. For ASB-12M compatible moulds like 150ml ISBM mould assembly 1×12 cavity, standardized designs achieve 15-25% lower pricing than equivalent custom moulds.
Changeover Time Scaling
Mould changeover time scales with cavity count because more cavities mean more individual components requiring precise alignment. Typical Korean production line changeover times:
- ▸2-cavity changeover: 1.5-2.5 hours
- ▸4-cavity changeover: 2-3 hours
- ▸8-cavity changeover: 3-4 hours
- ▸12-cavity changeover: 4-6 hours
For producers running 3-5 SKU changeovers per week, the 12-cavity mould absorbs 18-30 hours weekly in changeover versus 8-12 hours for 4-cavity. This time cost matters for multi-SKU contract fillers serving K-beauty brand portfolios.
Tolerance Tightening Requirements
Higher cavity counts require tighter dimensional tolerances to ensure consistent bottle production across all cavities simultaneously. A 4-cavity mould tolerates ±0.05mm variation across cavities. A 12-cavity mould must hold ±0.02mm or bottle-to-bottle variation becomes visible in finished product. This precision increases mould manufacturing cost and requires tighter production parameter control.
7. Multi-SKU Flexibility Strategy
Korean contract fillers and brand portfolio producers face the flexibility question that commodity producers avoid. When a single machine serves 8-15 SKUs, cavity count cannot optimize for any single SKU. Three strategies address this.
STRATEGY A
Size for Largest SKU
Select cavity count to handle your highest-volume SKU at full capacity. Accept lower efficiency on smaller SKUs.
Best for: Portfolio with one dominant SKU plus supporting smaller runs. Simple to plan, no under-capacity risk.
STRATEGY B
Two-Machine Split
Use two machines with different cavity counts. Large-volume SKUs run on 8-cavity machine, small-volume SKUs on 4-cavity machine.
Best for: 10+ SKU portfolios with meaningful volume differences. Higher capital but much better efficiency.
STRATEGY C
Cavity Blanking
Design higher-cavity mould with ability to blank individual cavities. Run at full 8 cavities for big orders, blank to 4 cavities for small orders.
Best for: Single machine deployments needing wide order size flexibility. Moderate complexity.
8. Korean Scaling Patterns: 1 to 10 Machines
Observed growth patterns across Korean bottle producers reveal predictable cavity and machine count progressions as brands scale from startup to established operation. Understanding these patterns helps forecast when to expand capacity.
| Operating Stage | Annual Volume | Typical Configuration |
|---|---|---|
| Startup (Year 1-2) | 0.5-2 M bottles | 1 machine, 2-4 cavity |
| Growth (Year 3-4) | 2-8 M bottles | 1-2 machines, 4-8 cavity |
| Scale (Year 5-7) | 8-25 M bottles | 3-5 machines, 6-12 cavity |
| Established (Year 8+) | 25-100+ M bottles | 5-10+ machines, 8-16 cavity |
Three transitions deserve attention. The first capacity expansion (1 to 2 machines) typically occurs at 2-3 million annual bottle volume when single-machine production cannot reliably serve demand growth plus inevitable maintenance windows. The second transition (2 to 3-4 machines) occurs at 8-10 million volume when SKU portfolio diversification requires dedicated machine allocation. The third transition (4 to 6+ machines) occurs at 20+ million volume when redundancy and throughput density both become operational requirements.
Each transition takes 6-12 months for procurement and commissioning. Korean producers who plan capacity expansion 12-18 months ahead of projected demand consistently outperform those who wait until capacity constraint forces emergency procurement.
9. Foire aux questions
Q: Can I add cavities to my existing mould later if demand grows?
No. Cavity count is fixed by mould design and cannot be field-upgraded. If you anticipate demand growth, choose cavity count with 25-40% headroom above current forecast. Alternatively, purchase a second identical machine and mould combination when demand exceeds single-machine capacity. This approach also provides production redundancy against maintenance downtime.
Q: Should I go with a higher cavity count just to be safe?
Not automatically. Higher cavity count increases mould capital 40-60% per additional cavity and extends changeover time 30-50%. For multi-SKU contract fillers running 3-5 weekly changeovers, higher cavity count can actually reduce annual production throughput after accounting for lost changeover hours. Size cavity count for your specific operating profile rather than maximum theoretical capacity.
Q: How does double-row cavity compare to single-row high cavity?
Double-row architecture (like HGY250-V4-B) effectively doubles throughput density in similar footprint. For example, a double-row 6-cavity configuration delivers equivalent throughput to single-row 12-cavity while occupying the same floor space. The trade-off is double-row requires precise blow station balance and slightly more complex cooling circuit design. For 1-2L bottle applications with high volume, double-row typically outperforms single-row at equivalent cavity count.
Q: What cavity count should I use for my pilot line before full production?
Pilot production typically uses 2-4 cavity configurations to minimize capital risk while validating bottle design, parameter optimization, and market acceptance. Once commercial volume forecast is confirmed (typically 6-12 months into pilot), scale to full production cavity count with a second mould designed for validated specifications. Korean K-beauty brand launches commonly follow this 2-cavity pilot to 8-cavity scale path.
Q: Does cavity count affect bottle-to-bottle quality consistency?
Higher cavity count increases risk of bottle-to-bottle variation if mould manufacturing tolerances are not tight. Each cavity is independent and must produce identical output. At 4 cavities, managing cavity-to-cavity consistency is straightforward. At 12+ cavities, precision mould manufacturing with ±0.02mm tolerance and balanced hot runner flow becomes essential. For premium K-beauty and pharmaceutical applications, higher cavity counts require additional quality control investment.
10. Conclusion
Cavity count selection is the most undervalued decision in ISBM procurement. Most buyers spend weeks evaluating machine platforms and bottle design, then default to vendor recommendation on cavity count during the final week of procurement. This approach produces expensive selection errors that compound over 7-year operational horizons.
The structured approach is simple: calculate required cavity count from annual volume target using the core formula, verify the calculation against bottle-volume cavity range constraints, evaluate hidden costs (mould capital, changeover time, tolerance requirements), and apply multi-SKU flexibility strategy if needed. This discipline converts cavity count from intuition into defensible calculation.
For Korean producers evaluating cavity count for new capacity or capacity expansion, Ever-Power’s 12-platform catalog and Custom One-Step ISBM Mould service support cavity counts from 1 to 16 depending on bottle specification. Our Korean engineering team provides cavity calculation and platform matching as part of standard pre-purchase consultation.
Need Cavity Count Calculation for Your Application?
Share your bottle specification, target annual volume, operating schedule, and SKU portfolio. Our Korean engineering team returns cavity count recommendation with platform matching, mould capital estimate, and sensitivity analysis within 48 hours.
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Éditeur : Cxm
