PLM, controlled.
Also called: PLM · Product data management · Source of truth · Revision control
One controlled place that holds the released design version, the BOM and the change log, so the factory always builds the right revision.
PLM is keeping a single controlled source of truth for the current design version, the bill of materials, the drawings and every change. Without it, two suppliers build two different products. For a lean team this is a tidy shared folder and a sheet, not enterprise software.
What a PLM system is
Product lifecycle management is the discipline of holding one controlled source of truth for everything that defines the product: which design version is released, what the bill of materials says, which drawings are current, and a log of every change since the last release. Every supplier, and every future version of you, pulls from that one place.
The word “system” scares lean teams into thinking they need expensive PLM software. They don’t. A system is just a place plus a rule: one folder or one sheet that holds the released files, and a rule that nobody builds from anything else. The discipline matters far more than the tooling. I have seen a shared drive with a strict naming convention outperform a six-figure platform that nobody trusted.
The job it does is simple to state and easy to skip: make sure the Stoke-on-Trent maker and the Manchester PCB house are both holding the current revision on the day they cut metal and order boards. Get that wrong and you have paid to manufacture last month’s design.
What it holds, on the proofing box
Here is what the proofing box’s controlled source of truth actually contained, kept deliberately lean so a two-person team could maintain it. Notice it is a folder and a sheet, not a platform.
The same idea, run two ways. The left column is what happens with no controlled source of truth; the right is the tidy shared system doing its job.
- CAD lives in three inboxes and two laptops; nobody knows which is current.
- The maker quotes from a drawing you superseded a month ago.
- A BOM change is agreed in a call and never written down.
- The factory builds the old revision; you find out at first article.
- One controlled folder; the RELEASED file is unmistakable.
- Every supplier pulls the same current revision, by link.
- Every change is logged with a date, a reason and a new rev letter.
- The factory builds the right revision because there is only one to build.
How it fits the bigger picture
PLM system is activity 09.10.06 in Stage 09 Manufacture. It sits under everything the factory touches, holding the released design steady while production runs. Once the source of truth is controlled, the next activity, the master production schedule (09.20.01), plans what gets built and when, against that one trusted revision.
What it can do
It guarantees that every supplier is building the same thing: the current released revision, with a BOM and drawings that match. It makes changes deliberate and traceable, so you can answer “which revision is in this batch?” months later without guessing.
What it can’t do
It can’t decide whether a change is a good idea; that is engineering judgement. And it won’t run itself. A controlled source of truth only works while the team keeps to the rule that nobody builds from anything outside it. The moment someone emails a drawing direct, the system has a leak.
See the full 10-stage process →
Try it yourself
Pick one place to be the source of truth: a single cloud folder will do. Move the current CAD, BOM and drawings into it, mark the released set clearly with a revision letter, and archive everything older where nobody can build from it. Start a one-line change log. Then tell every supplier: this link is the only place you pull files from. Hold that line and you have a working PLM system.
Want the whole 10-stage path mapped to your product first? Start the Free Sprint → and the GPT will frame where your design data needs to be controlled.
Your PLM checklist
Project notes: the rev that nearly shipped twice
▸ From the notebook · optional reading
How a near-miss in Stockport made us build a one-folder, one-sheet source of truth, and how it caught the next change before the factory did.
3 min read · click to open
Early on, with Dan and Anna Hartley in Stockport, there was no real PLM. The CAD lived on Dan’s laptop, the BOM in an email thread, and the heater drawing had been revised twice in a fortnight. The Stoke-on-Trent maker quoted the ceramic shell off a drawing that was already two revisions old, because that was the one still in his inbox.
We caught it, just, when the quote came back with a wall thickness that no longer matched the current rev. Half a day lost, no money. But it was a clear warning: with two suppliers and a moving design, scattered files would eventually ship the wrong revision.
What we built instead
Nothing clever. One cloud folder as the source of truth. The RELEASED design set, the BOM, every drawing and the UKCA / BS EN 61010 file went in it, with the current revision marked plainly and older versions shoved into an archive subfolder. One sheet became the change log: date, what changed, why, who approved, and which supplier was told. Dan was the only person who could promote a file to RELEASED.
Total cost: zero, beyond the discipline. No PLM licence, no new tool to learn. The whole thing fit in software the team already paid for.
Where it earned its keep
A month later we changed the PCB heater track to drop a degree of overshoot. Old way, that change would have lived in a phone call and a couple of inboxes. This time it was a logged rev, a fresh file marked RELEASED, and a single message to the Manchester PCB house pointing at the link. They built the right boards first time. I asked Dan, weeks later, whether the folder felt like overhead. His answer: it had quietly stopped two more old-revision quotes he had not even noticed.
For a lean team, that is the whole case. Not a platform. A place, a rule, and a habit of writing changes down.
— Manufacture stage, project notes, 2026
— Next in Manufacture → Master production schedule