At what order quantity is die casting cheaper than CNC machining?

The break-even point is N = tooling cost ÷ (machined unit cost − cast unit cost). For a typical die-castable aluminium part, the practical crossover at Boyang Hardware is around 2,000 pieces: below that, CNC machining (which needs no tool) is cheaper in total; above it, the die amortises and casting wins. The exact number depends on tooling cost and the per-piece saving — use the sensitivity table on this page rather than a single threshold.

Why is the break-even often quoted as 2,000 pieces?

Because the two variables behind the formula usually land in a similar range for mid-size aluminium parts: die tooling in the low thousands of dollars and a per-piece saving of roughly one to three dollars between casting and machining. Dividing one by the other lands near a couple of thousand pieces. Parts with bigger geometry or tighter tolerance need machining even at high volume, because casting alone cannot hold the critical dimensions.

Can die casting and CNC machining be combined on one part?

Yes, and this is often the best answer at volume. The part is die cast to near-net shape (±0.05 mm), then the critical features — bearing bores, sealing faces, threaded holes — are machined. Boyang Hardware runs both processes in one facility in Zhongshan, so the cast blank and the machining operations are coordinated under one quotation and one inspection standard.

Die Casting vs CNC Machining: Where the ~2,000-Piece Break-Even Comes From

The formula, a worked example and a sensitivity table — from a facility that runs both processes under one roof

Direct answer The break-even quantity between die casting and CNC machining is

N = tooling cost ÷ (machined unit cost −
        cast unit cost)

. For a typical die-castable aluminium part, the practical crossover is around 2,000 pieces: below it, CNC machining is cheaper in total because it needs no tool; above it, the die amortises and casting wins. Tooling lead time (4–10 weeks for a die) and tolerance are also decision inputs: casting holds ±0.05 mm while machining holds ±0.01–0.001 mm, so parts with critical fits need machining even at high volume — usually as casting plus finish machining.

~2,000pieces: die casting crossover
1piece: machining economical from
4–10 wkdie tooling lead time
±0.05 mmdie casting tolerance
±0.01 mmCNC tolerance typical
2processes, one facility

The break-even formula

Total cost of each option over N pieces:

CNC total = N × C(machined unit cost)
Die cast total = T(die tooling) + N × D(cast unit cost)

The two lines cross where the die has paid for itself:

N* = T ÷ (C − D)

Three inputs decide everything: what the die costs, what the per-piece saving is, and how many pieces you will actually buy over the life of the programme — not just the first order.

Worked example

Note: the dollar figures below are illustrative only and are not Boyang Hardware quotations. They are chosen to demonstrate the arithmetic. Real numbers depend on your geometry — send the drawing for an actual routed quotation.

Take a mid-size aluminium housing, die-castable geometry, machinable from plate:

Machined unit cost C = $9.00 (illustrative)
Cast unit cost D = $5.50 (illustrative)
Die tooling T = $8,000 (illustrative)

Break-even:

N* = 8,000 ÷ (9.00 − 5.50) = 8,000 ÷ 3.50 ≈ 2,286 pieces

So the first ~2,300 pieces of the programme pay for the die; every piece after that saves $3.50 against machining. At 500 pieces the die is mostly unamortised waste — machining wins. At 20,000 pieces casting has saved 20,000 × 3.50 − 8,000 = $62,000 — casting wins decisively.

Sensitivity table — how the crossover moves

Table 1 — Break-even quantity N* = T ÷ (C − D) for a range of tooling costs and per-piece savings. Illustrative arithmetic, not quotations.
Tooling T \ Saving (C−D)	$2.00	$3.50	$5.00
$5,000	2,500 pcs	1,429 pcs	1,000 pcs
$8,000	4,000 pcs	2,286 pcs	1,600 pcs
$12,000	6,000 pcs	3,429 pcs	2,400 pcs

Read the table honestly: a part with a small per-piece saving and expensive tooling does not break even until 4,000–6,000 pieces. "~2,000 pieces" is a rule of thumb for typical cases, not a law — which is why Boyang Hardware quotes the routed comparison instead of asserting a universal threshold.

Beyond unit cost: three more decision inputs

Table 2 — Non-price factors, from the process comparison on the main site.
Factor	CNC machining	Die casting
Tooling lead time	None	4–10 weeks
Tolerance	±0.01–0.001 mm	±0.05 mm
Design change after start	Drawing change only	New tool (or costly die rework)
Wall thickness / draft limits	None — geometry is free	Die rules apply: draft, uniform walls, ejector marks
Materials	Any machinable metal or plastic	Aluminium, zinc, brass
Economical from	1 piece	~2,000 pieces

The combined route: cast the blank, machine the criticals

At volume the best answer is usually both processes: die cast to near-net shape at ±0.05 mm, then machine the features the casting cannot hold — bearing bores, sealing faces, threaded holes — to ±0.01–0.001 mm. This captures most of the casting saving while keeping critical fits machined. Boyang Hardware runs die casting and CNC machining in the same 3,000 m² Zhongshan facility, so blank, machining and 100% final inspection are coordinated under one quotation and one quality standard. If you also need plastic parts for the same assembly, injection moulding is available in-house alongside — see the full process comparison.

FAQs

Does the 2,000-piece rule apply to investment casting too?

No — investment casting has cheaper tooling and looser tolerance (±0.10 mm), so its crossover is lower, around 500 pieces. Injection moulding of plastics breaks even much higher, around 5,000 pieces. See the process comparison page.

What if I need 500 pieces now and 20,000 next year?

Start machined — no tool risk while the design settles. When volumes firm up, the same drawings are re-quoted as cast-blank-plus-machining, and the die is only ordered once the design is stable. Both processes run in one facility, so the transition keeps the same inspection standard.

Can I get both options priced on one drawing?

Yes — that is the standard way this question is answered. Send the drawing; the quotation (1–2 working days) states both routes with tooling cost, unit prices and lead times, so the break-even is visible rather than asserted.