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What production volume suits injection moulding?
Injection moulding usually suits runs from the hundreds or low thousands of parts upward, because the mould is a large fixed cost that gets cheaper per part with every part made; MakerVerse puts the break-even with other processes at roughly 500 to 2,000 parts.
There is no single magic number. The crossover depends on the size and complexity of the part, the mould you choose, the material, and how stable the design is. What every publisher agrees on is the shape of the curve: high fixed cost, low cost per extra part.
The arithmetic
The basic sum is:
cost per part = mould cost ÷ quantity + material + moulding labour
MakerVerse gives a fuller version: direct materials, plus direct labour, plus manufacturing overhead, plus amortised tooling, plus scrap, divided by the good parts actually shipped. The fuller version matters because scrap and overhead do not disappear at high volume.
Published worked examples
MakerVerse shows how a representative €5,000 mould spreads across a run:
| Quantity | Tooling share per part (MakerVerse) |
|---|---|
| 500 | about €10 |
| 5,000 | about €1 |
| 10,000 | about €0.50 |
MakerVerse also gives a second example: a $20,000 mould with $0.15 of material and $0.25 of processing per part comes to $2.40 per part at 10,000 units, $0.80 at 50,000 and $0.60 at 100,000.
Formlabs publishes a three-scenario example for a small enclosure, in which the cheapest mould type changes with volume (equipment costs excluded):
| Volume | Mould (Formlabs) | Mould cost | Cost per part |
|---|---|---|---|
| 100 | 3D-printed polymer | $100 | $4.00 |
| 5,000 | Machined aluminium | $3,000 | $2.60 |
| 100,000 | Machined steel | $20,000 | $1.70 |
Formlabs adds that using the aluminium mould for only 100 parts would put about $30 of tooling on each part, and a steel mould about $200. MakerVerse gives similar orders of magnitude for a 100-part run: roughly €30 to €80 of tooling per part with aluminium and €150 to €800 with production steel.
Where published break-even points fall
Sources do not agree on one crossover, and the differences are worth knowing:
| Source | Lower volumes | Injection moulding |
|---|---|---|
| MakerVerse (cost per part) | 3D printing below roughly 50 to 100 parts; CNC machining from 50 to 2,000 | breaks even between 500 and 2,000 parts |
| MakerVerse (FAQ) | 3D printing below about 50; CNC about 50 to 500 | 500 to 100,000+ parts |
| TWI | 3D printing for runs of 100 parts or fewer | ideal for 1,000+ parts per run |
MakerVerse's own volume table describes 1,000 to 10,000 units as a crossover zone between CNC machining and moulding, with moulding winning above 10,000. Read all of these as planning bands, not thresholds: a small simple part reaches break-even much sooner than a large part with side actions.
How to decide for your part
- Fix a realistic quantity. MakerVerse advises locking the annual or project quantity before asking for any quote. Use first-year demand you can defend, not the hoped-for number.
- Get a tooling quote and a piece price at that quantity, and at two or three other quantities, so you can see the curve.
- Add the costs that sit outside the piece price: trial rounds, inspection, packaging and freight.
- Run the same sum for the alternative process (3D printing or CNC machining) at the same quantities.
- Price the cost of change. MakerVerse lists around €500 to €3,000 per mould modification, and TWI notes that some design changes mean remaking the mould entirely.
- Check that the mould's expected life covers your total volume; a tool that wears out halfway through means paying for tooling twice.
- Decide whether a staged route fits better: printed or machined parts while the design moves, then an aluminium mould, then steel when demand is proven.
Volume is not the only reason to mould
Some projects choose moulding below the break-even point because they need parts in the real production resin for testing, the moulded surface finish, or moulding-specific features such as living hinges and snap fits. Others stay with printing or machining above it because the design is still changing. TWI notes that 3D printing allows design changes even during production, whereas a mould has to be remade to change the design.
Both worked examples are illustrations from their publishers, not quotes for a real part. Run the numbers with your own quotes.
Questions buyers ask
Is 1,000 parts enough to justify a mould?
Often, for a small and simple part. MakerVerse puts break-even between 500 and 2,000 parts and TWI describes moulding as ideal from 1,000+ parts per run. For a large or complex part the break-even moves higher, so ask for quotes from both a moulder and a machining or printing supplier.
What if my demand is uncertain?
Quote at a low and a high quantity and see how much the piece price moves. A cheaper aluminium tool limits the upfront risk, at the cost of a shorter tool life; the article on whether to choose an aluminium or steel mould covers that trade-off.
Does a multi-cavity mould change the break-even?
Yes. More cavities raise the mould cost but cut the moulding time per part, so they push the break-even up but lower cost at high volume. They make sense once annual quantity can keep the extra cavities busy.
Should I count later-year volume when choosing the mould?
Count the volume you can reasonably expect over the mould's life, and check that the quoted tool class covers it. Paying for a long-life tool before demand is proven is a common way to over-spend on tooling.
Sources
- MakerVerse, Injection molding FAQ: https://www.makerverse.com/resources/injection-molding-faq/
- MakerVerse, Cost per part: https://www.makerverse.com/resources/cost-per-part/
- Formlabs, Injection molding cost: https://formlabs.com/blog/injection-molding-cost/
- TWI, 3D printing vs injection moulding: https://www.twi-global.com/technical-knowledge/faqs/3d-printing-vs-injection-moulding