From prototype to series production: the stages of industrialisation

Industrialising means moving from one working unit to repeatable production, with controlled cost and quality. The typical path has six stages, which sometimes overlap:

1. Scoping: function, constraints, target volumes, target cost, applicable regulations.
2. Mock-up: validate shape, size and ergonomics.
3. Functional prototype: validate real-world operation.
4. Design for manufacturing and choice of series processes.
5. Tooling and pre-series: make the tooling (moulds, cutting tools, jigs) and produce the first parts with the series process.
6. Qualification and series launch.

The first three stages cost little and are easy to redo; the later ones commit investments that are hard to recover. The earlier a mistake is found, the less it costs: that is the whole point of prototypes before tooling.

What to decide at the scoping stage

Set the annual volumes you expect, the product’s lifespan, the target cost per part, the standards or regulations of your sector and the dimensions that are truly critical. For each stage, also define what will allow you to decide to move on to the next: without written success criteria, a prototype proves nothing and iterations follow one another endlessly.

The mock-up

It does not need to work. It is used to judge shape, size and handling, and to discuss them with stakeholders. It is made from substitute materials, most often by 3D printing, with foam, wood or cut parts: it is quick and inexpensive.

The functional prototype

It checks real behaviour: mechanical, thermal, sealing, assembly. It is made by CNC machining, laser-cut sheet metal or 3D printing, depending on the part. When the function depends on the material, choose a process close to the series one: a prototype printed in resin does not behave like a part injection-moulded in polyamide. To weigh up processes, see our comparison 3D printing or CNC machining.

Write down before manufacture what this prototype must demonstrate and how you will measure it. Plan for several iterations, and remember that a single part carefully machined does not prove that the series will hold the same tolerances. A prototyping workshop can help you frame these first trials.

DFM (design for manufacturing) adapts the design to the series process; DFA (design for assembly) makes assembly easier. A few reflexes depending on the process:

• Machining: internal radii compatible with milling cutters, shallow pockets, tight tolerances limited to functional dimensions.
• Sheet metalwork: uniform bend radii, holes kept away from bends (see the guide to laser cutting and bending).
• Plastic injection: even wall thicknesses, draft angles, ribs rather than thick sections.
• Assembly: fewer parts, standard fasteners, symmetrical shapes or poka-yoke features, access for tools.

As quantity rises, investing in tooling to reduce unit cost becomes worthwhile. The break-even point is simple to calculate: tooling cost divided by the saving made on each part. Thresholds vary a lot from one part to another; this table gives the general logic.

For plastic parts, see the plastics processing expertise page. Ask for quotes at several quantities: the price curve shows where tooling becomes worthwhile.

Finally, watch the continuity of material and process. A part prototyped in machined aluminium and then produced by casting, or printed and then injection-moulded, has neither the same structure nor the same tolerances: repeat the key tests on parts made with the series process.

Injection moulds, cutting or stamping tools, welding jigs, machining fixtures, inspection gauges: tooling is often the first investment item and the slowest to obtain. Three points deserve to be settled from the outset.

• Correction margin. After the first trials, the tool almost always needs correcting. It is easier to remove material than to add it: toolmakers often machine first with a little extra material left on.
• Expected tool life, which depends on the tool material and the material being processed: state your total volumes so that the toolmaker sizes the tool accordingly.
• Ownership and custody. Who owns the tool you finance? Where is it stored, who maintains and insures it, on what terms is it returned to you, can it be used for another customer? These points are settled in writing, in the quote or the contract. See our guide to protecting drawings and tooling.

Not everything requires heavy tooling. For modest volumes, modular fixtures, machining set-ups or 3D-printed jigs often avoid an investment that would never be recouped.

The pre-series

This is a small run made with the final tooling and process. It checks production capability, assembly, cycle rates and inspection, and often supports validation tests (environmental, endurance).

First article inspection (FAI)

A first article made with the series process is fully inspected: every characteristic on the drawing is measured, materials and certificates are checked, and everything is recorded in a report. This inspection is formalised in aerospace (standard EN 9102).

PPAP

Originating in the automotive industry, PPAP is an approval file for the production process. It demonstrates that the process repeatedly makes conforming parts: drawings, dimensional results, materials, control plan, risk analyses.

These frameworks apply only if your sector or your end customer requires them. In other cases, a dimensional report on the first batch and a simple control plan are often enough. A laboratory or an inspection and metrology workshop can carry out these measurements.

Durations vary enormously: rolling out an existing machined part takes far less time than creating a moulded product. These orders of magnitude mainly show the sequence.

The critical path almost always runs through tooling. Launch the purchasing of specific materials and the preparation of inspection in parallel.

To shorten the schedule, limit the number of iterations with a good design review, if possible choose a partner able to make both the prototype and the series, and allow a margin for tooling corrections rather than a schedule with no contingency.

• Freezing the design too early, or too late. Too early, you lock in flaws; too late, you delay the tooling.
• Validating with an unrepresentative prototype: material, process or tolerances different from the series.
• Underestimating tool tuning and its correction loops.
• Forgetting ancillary costs: inspection, packaging, logistics, certification.
• Changing supplier between prototype and series without passing on the know-how: up-to-date drawings, revision indices, inspection reports.
• Leaving rights over drawings and tooling unclear.
• Ignoring uncertainty over volumes: a bridge production in small runs avoids investing too early.