Shenzhen Alu Rapid Prototype Precision Co., Ltd.
Industry News
Short answer: Most hardware projects fail at the transition between prototype and production, not in either stage alone. Run four clear stages — prototype, EVT, DVT, PVT — and do not skip the functional prototype in the final material. Each stage answers a specific question, and each one de-risks the next.
The Four Stages
| Stage | Question it answers | Typical quantity | Typical process |
|---|---|---|---|
| Prototype | Does the shape and size work? | 1–5 | 3D printing, CNC |
| EVT (Engineering Validation) | Does it function and survive real conditions? | 5–50 | CNC, vacuum casting |
| DVT (Design Validation) | Does it meet spec, and can it be assembled repeatably? | 20–100 | Vacuum casting, bridge tooling |
| PVT (Production Validation) | Can the production line make it consistently? | 100–1,000 | Production tooling |
Stage 1 — Prototype
Goal: answer questions about form, fit, and ergonomics as cheaply and quickly as possible.
Use 3D printing for housings, covers, and non-structural parts
Use CNC machining when the part must hold real tolerances or be tested in metal
Do not over-invest in finish or cosmetics at this stage
See our comparison of rapid prototyping methods for picking the right process.
Stage 2 — Engineering Validation (EVT)
Goal: prove the design actually functions, in the real material, under real loads and temperatures.
Machine the parts in the final or near-final material
Run electrical, mechanical, thermal, and drop testing
Expect to iterate — plan for 2–3 rounds
This is the stage most teams under-budget. It is also the stage that catches the failures that would otherwise appear after tooling is cut.
Stage 3 — Design Validation (DVT)
Goal: confirm the design meets specification and can be assembled repeatably by someone other than the designer.
Produce 20–100 units that are visually and dimensionally consistent
Vacuum casting is the standard choice for plastic parts at this volume
Write assembly instructions and fixtures now, not later
Validate packaging and shipping
See our vacuum casting vs injection molding comparison.
Stage 4 — Production Validation (PVT)
Goal: prove the production process — not the prototype process — makes conforming parts at rate.
First parts come off production tooling or the production machining cell
Measure yield, cycle time, and defect rate
Finalize inspection criteria and acceptance sampling
Freeze the drawing and the supply chain
Bridging Between Stages
You rarely jump straight from a CNC prototype to a production mold. Bridge options fill the gap:
| Stage gap | Bridge option |
|---|---|
| Prototype → EVT | CNC in final material |
| EVT → DVT | Vacuum casting, 10–50 matching units |
| DVT → PVT | Aluminum bridge tooling or CNC production runs |
| PVT → mass production | Steel production tooling |
Bridge tooling costs far less than production tooling and lets you start selling or field-testing before committing. See our CNC machining vs injection molding breakdown for where the cost crossover happens.
Timeline Expectations
| Stage | Typical duration |
|---|---|
| Prototype (per round) | 3–10 days |
| EVT (per round) | 2–4 weeks |
| DVT | 3–6 weeks |
| Tooling + PVT | 6–12 weeks |
Total from first prototype to shipping production is commonly 4–9 months for a moderate-complexity product with two design iterations.
Five Mistakes That Cost the Most
Going straight from a printed model to tooling. Material behaviour is the most common late-stage surprise.
Freezing the design too early. Every change after tooling costs far more than the same change on a CNC part.
Ignoring assembly. A part that fits on the designer's desk may not assemble at rate.
Underestimating finishing. Coating, anodizing, and cosmetic requirements each add lead time.
No plan for the bridge. Teams either over-pay for production tooling too early, or wait months for it.
FAQ
What does NPI mean?
New Product Introduction — the process of taking a product from design through validation to production.
What is the difference between EVT, DVT and PVT?
EVT proves the engineering works, DVT proves the design meets spec and assembles repeatably, and PVT proves the production process can make it consistently at volume.
How many prototypes should I make?
Start with 1–5 for form and fit, then 5–50 in the final material for functional validation before ordering tooling.
Do I need production tooling to start selling?
No. Bridge tooling or CNC production runs let you ship early volumes while validating demand.
What is the biggest cause of delay?
Late design changes after tooling. Front-loading validation in the material you will actually produce in avoids most of it.
Plan Your Next Stage
Tell us which stage you are at and what question you need answered. We will recommend the process and quote it — from a single prototype to a pilot build.