Production 3D CAD, locked.
Also called: Production-intent model · Release model · Manufacturing master CAD · Frozen geometry
The final, fully toleranced 3D model of every part, revision-controlled and released as the single source the factory builds from.
Production 3D CAD is the design frozen for manufacture. Every feature, tolerance, material and finish is locked, given a revision, and released. Suppliers quote and cut from this model, nothing else. Change it after release and you change it under formal control.
What production 3D CAD is
Production 3D CAD is the moment the geometry stops moving. Up to here the model has been a working draft: features added and pulled, dimensions nudged, tolerances left open while the design settled. At release, all of that closes. Every face, radius, wall thickness, fit and finish is decided, dimensioned and locked, and the model is stamped with a revision and issued to the people who will make it.
The point is that there is exactly one authoritative model. When the Stoke-on-Trent maker quotes the ceramic shell and the Manchester PCB house lays out the carrier, they are both reading the same released file. Nobody works from a screenshot, an email or last week’s draft. If the part on the bench does not match the released model, the part is wrong, not the model. That single rule is what production CAD buys you.
It is also where manufacturability stops being theoretical. A draft model can ignore draft angles, shrinkage, fastener access and how a tool actually fills. The production model cannot. Every choice now has to survive contact with a real process and a real supplier, which is why this activity sits in Manufacture and not in Design.
What “locked” actually means
- Toleranced, not nominal. Every dimension that matters carries a tolerance. A nominal-only model tells the factory what you hope for, not what you will accept.
- Material and finish specified. The model names the clay body, the wood, the board stack-up and the surface finish. “Looks like ceramic” is not a release state.
- Revision-controlled. The model has a revision letter and an issue date. The previous draft is archived, not deleted, so you can always see what changed and why.
- Released, not shared. There is a deliberate act of release. Before it, the model is a draft anyone can edit; after it, changes go through change control.
The shape to notice: this is a record of decisions, not a wish-list. Every cell is something a supplier can quote against and a part can be measured against. That is the difference between a model and a release.
- Nominal dimensions, no tolerances; the factory guesses what you will accept.
- No revision, no issue date; nobody knows which file is current.
- Shrinkage and process allowances left out; the first ceramic run comes back undersized.
- Material and finish vague; two suppliers quote two different products.
- Every critical dimension carries a tolerance the supplier can hold.
- Released at a stated revision and date; one current file, archived history.
- Firing shrinkage built into the geometry, so parts arrive on size.
- Material, finish and stack-up named; both suppliers quote the same product.
How it fits the bigger picture
Production 3D CAD is activity 09.10.01 in the framework, the first activity of Stage 09 Manufacture. It takes the design-stage geometry and freezes it for production. Once the model is released, production drawings (09.10.02) are generated directly from it: the 2D record, GD&T and inspection dimensions a maker signs off against.
What it can do
It gives the factory one unambiguous thing to build. Suppliers quote against it, cut against it, and inspect against it. When a part comes back wrong, the released model settles the argument in minutes rather than days, because there is no question about which version was correct.
What it can’t do
It can’t prove the part will actually make. That is what tooling reviews, first-article inspection and the early production run confirm. The model is the intent; the process still has to be capable of holding it, and a sensible release expects a revision or two once the first parts come off the line.
See the full 10-stage process →
Try it yourself
Take your latest design model and ask the release questions, one part at a time. Does every dimension that matters carry a tolerance? Is the material and finish named, not implied? Is process allowance (shrinkage, draft, machining stock) built into the geometry? Does the file have a revision and a date? If any answer is no, it is still a draft, however finished it looks. Only release what a supplier could quote and cut without ringing you to ask a question.
Want to get the earlier stages right so the model is genuinely ready to lock? Start the Free Sprint → and work the idea through to a buildable definition.
Your production-CAD checklist
Project notes: freezing the shell
▸ From the notebook · optional reading
Building firing shrinkage into the ceramic model before release to Stoke-on-Trent, and the one tolerance that nearly went out wrong.
3 min read · click to open
The design model of the proofing box looked finished. It was not. The shell read as the size we wanted it to end up, and ceramic does not work that way: it shrinks in the firing, and the maker needs the bigger, green-state geometry to start from.
So before anything went to Stoke-on-Trent, we worked the shrinkage into the model itself rather than leaving it as a note on a drawing. I asked the maker for their measured shrinkage figure for the clay body we had chosen, not a textbook number, and we scaled the shell and lid geometry up accordingly. The released model is the green part; the fired part lands on the dimension we actually want.
The tolerance that nearly slipped
The lid-to-shell fit was the one that nearly caught us. The first draft had it toleranced like a machined part, far tighter than a ceramic process can hold. Released as drawn, every other lid would have been a reject. We opened it to a fit the maker could actually deliver and added a thin compliant gasket to take up the slack, then re-toleranced the carrier the other way: tight to the board it locates, deliberately loose to the shell it sits inside.
Then, and only then, release
- Ceramic shell, lid and wood band released to the Stoke-on-Trent maker at Rev A.
- PCB carrier released to the Manchester PCB house, same day, same revision stamp.
- One reason line per part, so when Rev B inevitably arrived after the first samples, we could see exactly what moved.
Two revisions came back off the first run, both small, both expected. Because the model was the single source and every change was logged, neither caused an argument about which file was right. The whole point of freezing the geometry is that disagreements become checkable rather than political.
— Manufacture stage, project notes, 2026
— Next in Manufacture → Production drawings