How The Number of Cavities in An Injection Mold Affects Production

1. Single-Cavity Molds (1 Cavity)

Pros:

✅ Lower initial cost – Simpler design means cheaper tooling.
✅ Easier quality control – Fewer variables mean more consistent parts.
✅ Flexible for complex parts – Ideal for large or high-precision components.

Cons:

❌ Low output – Only one part per cycle, leading to slower production.
❌ Higher per-unit cost – Less efficient for mass production.

Best For:

• Prototyping & low-volume production.

• Large or intricate parts (e.g., automotive components).

2. Multi-Cavity Molds (2–64+ Cavities)

Pros:

✅ Higher production rates – More parts per cycle = faster output.
✅ Lower per-unit cost – Economies of scale reduce manufacturing expenses.
✅ Efficient for small, simple parts – Ideal for high-volume orders.

Cons:

❌ Higher upfront cost – Complex design increases tooling expenses.
❌ Harder to balance – Uneven filling can cause defects (short shots, warping).
❌ Maintenance challenges – One damaged cavity may halt entire production.

Best For:

• Mass production of small, uniform parts (e.g., bottle caps, electrical connectors).

3. Family Molds (Different Cavities in One Mold)

Pros:

✅ Reduces assembly time – Produces multiple related parts in one cycle.
✅ Saves on mold changes – No need for separate tools.

Cons:

❌ Design complexity – Different parts may have varying shrinkage rates.
❌ Risk of inefficiency – If demand shifts, some cavities may go unused.

Best For:

• Low-volume production of matched components (e.g., enclosures with lids).

4. Key Factors in Choosing Cavity Count

5. Real-World Example

• Single-Cavity Mold:
  Producing car headlight housings (large, high-precision) → 20 parts/hour, 95% yield.

• 8-Cavity Mold:
  Producing plastic bottle caps (small, simple) → 8,000 parts/hour, 92% yield, 70% cost reduction per unit.

Conclusion: How to Choose the Right Cavity Count?

• For prototypes/complex parts? → Single-cavity (better control).

• For mass production? → Multi-cavity (higher efficiency).

• For matched components? → Family mold (reduces assembly steps).

The best choice depends on production volume, part complexity, and budget. A balanced approach (e.g., starting with 2 cavities and scaling up) can help optimize costs and efficiency.