Control plan template: a free guide with a worked example.
A control plan is the one document that turns "we know how to make this part" into "we can prove we control how we make this part." Here is every column explained, a worked machined-part example, and how it ties to your PFMEA and PPAP submission.
What a control plan is
A control plan is a structured table that, for every step of your process, states what you control, how tightly, how you measure it, how often, and what you do when it drifts. It is a living document under the APQP framework and a required element of every PPAP submission. Done well, it is the operating manual for quality on the line; done badly, it is a binder nobody opens until an auditor asks for it.
In my 14 years as a plant head, the difference between a plant that holds its quality and one that fights fires was almost always the control plan. A real control plan tells the operator exactly which three dimensions to check, with which gauge, every twentieth part — and what to do the moment one goes out.
The three phases
AIAG defines three control plan phases that track the life of a part:
| Phase | When | Focus |
|---|---|---|
| Prototype | Early builds | Dimensional and material checks to prove the design |
| Pre-launch | Before mass production | Enhanced controls, higher sampling, capability studies |
| Production | Ongoing manufacturing | Established controls, normal frequency, reaction plans |
Most of the control plans you maintain day to day are production control plans. Pre-launch typically runs tighter sampling until you have demonstrated process capability — for example, holding a Cpk study before relaxing to a routine frequency.
Every column, explained
The AIAG control plan format has a standard set of columns. Here is what each one means and how to fill it:
- Part / process number & name: the operation, keyed to your process flow diagram (e.g., OP30 Drilling).
- Machine / device / jig: the specific equipment used, so the control is traceable to a workstation.
- Product characteristic: a feature of the part — ⌀5.00 hole, 50 mm length, surface finish.
- Process characteristic: the process setting that drives the product characteristic — spindle speed, feed, coolant pressure.
- Special characteristic class: the customer symbol for critical/significant features (e.g., a diamond or the letters CC/SC).
- Specification / tolerance: the drawing requirement with its tolerance band.
- Evaluation / measurement technique: the gauge or method — pin gauge, micrometre, CMM, profilometer.
- Sample size & frequency: how many and how often — 3 pieces every 2 hours, 100% on the first-off.
- Control method: how the process is held — SPC chart, error-proofing (poka-yoke), checklist, first-off approval.
- Reaction plan: what the operator does when a result is out — quarantine, adjust, inform supervisor, raise an NCR.
Worked example: a machined bracket
Here is a trimmed production control plan for OP30 (drilling) of a steel bracket:
| Characteristic | Spec | Method | Sample / freq | Control | Reaction |
|---|---|---|---|---|---|
| ⌀5.00 hole (CC) | +0.05 / −0.00 | Pin gauge go/no-go | 5 pcs / hour | SPC + first-off | Quarantine lot, change drill, re-check |
| Hole position | ⌀0.1 to A|B|C | CMM | 1 pc / shift | X-bar & R chart | Stop, verify fixture, contain |
| Deburr / finish | No sharp edge | Visual + comparator | 100% | Operator check | Rework edge, re-inspect |
Notice how the special characteristic (the critical ⌀5.00 hole, marked CC) gets the tightest sampling and an SPC control method, while a lower-risk visual feature gets a 100% visual check with a simpler reaction. Effort follows risk — that is the whole point.
How it links to PFMEA
The control plan does not invent its controls from nothing. It inherits them from the Process FMEA. The PFMEA identifies failure modes, scores severity, occurrence and detection, and computes a risk priority number. The high-RPN items and their recommended actions become the controls, sample sizes and reaction plans in your control plan.
Quantify that risk first with our FMEA RPN calculator, then carry the worst offenders into the control plan as tightened controls. If you are new to the link between the two documents, our guide to Gauge R&R shows why your measurement method choice in the control plan has to be capable enough for the tolerance it verifies.
How it links to PPAP
The control plan is a mandatory PPAP element. For an Indian OEM submission it must be current, signed, and consistent with the process flow diagram and the PFMEA — auditors cross-check all three. Build and track the full submission with our PPAP checklist tool, which lists every element by submission level so nothing is missing on the day you submit.
For the wider context on Indian OEM expectations, read PPAP for Indian OEMs, and use the ready-made forms in the MetricMech templates library to start from a compliant layout rather than a blank sheet.
Common mistakes
- Generic reaction plans. "Inform quality" controls nothing. Spell out contain, adjust, escalate.
- Inconsistent with the PFMEA. A high-RPN failure mode with no matching control is the first thing an auditor finds.
- Incapable measurement method. A caliper listed against a ±0.005 mm feature fails the 4:1 rule before you measure anything.
- Frozen document. The process changed but the control plan did not. Revision control matters here as much as on the drawing.
- Missing special characteristics. Customer critical/significant symbols not carried through from the drawing to the plan.