🎓 CSSBB Quest › Learn

Control Plan at Black Belt Level: Reaction Plans and Handoff

The control plan is the document that keeps the improvement alive after the project team leaves. It lists what will be measured, how, how often, by whom, and exactly what happens when a signal appears. At the Control tollgate, the Black Belt hands it to the process owner, who accepts responsibility for running it.

What the exam expects

Control plans and sustaining the gains sit in Control (VIII) of the 2022 CSSBB Body of Knowledge. Expect to know the columns of a control plan, link it to the FMEA and to SPC, choose a control method for a characteristic, write or judge a reaction plan, and explain what a clean handoff looks like.

Key concepts

Typical columns: process step, characteristic (product or process), specification or tolerance, measurement method, sample size and frequency, control method, reaction plan, and owner.
Process characteristics are the Xs proved in Analyze and Improve. Controlling the X keeps the Y in place, so the critical Xs belong on the plan, not just the output.
Hierarchy of controls: error-proofing that prevents the cause is strongest, then automatic detection and stop, then SPC, then manual inspection, then training and procedures alone.
Measurement first: every measurement method in the plan needs an acceptable MSA, or the chart will react to gage noise.
Control limits are not specification limits. Limits come from the stable improved process; specs come from the customer. A reaction plan triggers on an out-of-control signal, which in a capable process usually arrives before product goes out of specification.
Reaction plan: contain (stop, hold the product made since the last good check), correct (find and fix the assignable cause), verify (confirm the process is back in control), and document. It names who acts and who is notified.
Living document: updated when the process, the FMEA or the product changes, and checked in layered process audits.
Handoff: the process owner signs that they accept the plan, the procedures and training are updated, ownership of each chart is assigned, and the monitoring period for validating benefits is agreed.

Worked example: limits and control plan rows for a filling line

After Improve, the team collects 25 subgroups of n = 5 fill weights from the stable new process. Specification: 500 ± 5 g. Constants for n = 5: A₂ = 0.577, D₃ = 0, D₄ = 2.114, d₂ = 2.326.

X-double-bar = 500.4 g R-bar = 2.1 g UCL(X-bar) = 500.4 + 0.577 × 2.1 = 501.61 g LCL(X-bar) = 500.4 − 0.577 × 2.1 = 499.19 g UCL(R) = 2.114 × 2.1 = 4.44 g LCL(R) = 0 sigma-hat = R-bar / d2 = 2.1 / 2.326 = 0.903 g Cpk = min(505 − 500.4, 500.4 − 495) / (3 × 0.903) = 4.6 / 2.709 = 1.70

X-bar limits apply to subgroup averages, not single units, so never compare them directly with the specification. Individual fills at ±3 sigma-hat run from 497.7 to 503.1 g, inside 495 to 505 g, so a chart signal normally arrives before out-of-spec product is made.

Step / characteristic	Spec	Method, sample, frequency	Control	Reaction plan (owner)
Filling / fill weight (Y)	500 ± 5 g	Calibrated balance with acceptable gage R&R; 5 consecutive units every hour	X-bar and R chart, limits above	Point beyond a limit or run rule: stop filler, hold product since last in-control subgroup, find and correct cause, verify next subgroup, record on chart (operator, supervisor notified)
Filling / nozzle temperature (X from DOE)	62 ± 2 °C	Thermocouple, continuous	Automatic alarm and interlock	Line stops automatically; maintenance checks heater; restart only after temperature verified in range (maintenance technician)
Capping / cap present and seated	Seated, no tilt	Vision system, 100%	Automatic reject	Rejects go to a locked bin; 3 rejects within 10 minutes: stop and inspect capping head (operator)
Labeling / lot code	Matches batch record	Visual check at start-up and every lot change	Signed checklist	Mismatch: quarantine labeled product since last check, relabel, second-person verification (line lead)

Notice the mix: the critical X gets an interlock rather than a chart, the Y gets SPC, and only the lowest-risk item relies on a manual check.

Common exam traps

A reaction plan that triggers only when product is out of specification.
Drawing specification limits on the control chart, or calculating limits from pre-improvement data.
Recalculating control limits every month so that drift is quietly absorbed. Limits are revised only after a deliberate, verified process change.
A plan with no owner, no frequency, or "adjust as needed" as the reaction.
Relying on inspection and training when the cause could be error-proofed.
Confusing the control plan with the project plan or with the broader quality plan.

Check yourself

R-bar = 3.0 with n = 5: what is UCL for the R chart? (2.114 × 3.0 = 6.34.)
Why hold product back to the last good check, not just the current unit? (The shift may have started any time after that check.)
Which control is stronger: an SPC chart on the output or an interlock on the critical input? (The interlock: it acts on the cause automatically.)
Who owns the control plan after the Control tollgate? (The process owner, not the Black Belt.)

Test yourself in 2 minutes

Try 5 free CSSBB practice questions on this topic. No account needed.

Take the free CSSBB diagnostic

More: DMAIC overview · Project charter · VOC & CTQ · SIPOC · MSA in DMAIC · Process capability · Data collection planning · Graphical analysis · Root cause analysis · Multi-vari analysis · Hypothesis testing · Regression · DOE · FMEA · Define tollgate · Change management · Financial benefits · Team dynamics · Improve tollgate · Piloting & scaling · Poka-yoke (BB) · Solution selection · Control plan · SPC in DMAIC · Sustaining gains

CSSBB Quest by Bizarre Act. Original study material; not affiliated with ASQ. CSSBB is a certification of ASQ. Terms · Privacy