Process CapabilityCp and Cpk, what each one counts, and why only one of them is honest.Mechanical EngineeringCapability compares the tolerance width with theprocess spread, and Cpk also accounts for centring.Cp = (USL − LSL) ÷ 6σ · Cpk = nearest gap ÷ 3σTolerance ±0.1, σ = 0.02Cp = 1.670.2 ÷ 0.12.Mean drifts 0.04 offCpk falls to 1.00.06 ÷ 0.06.Cpk = 1.33About 63 parts per millionCommon target.THE COMMON MISTAKE✗ Reporting Cp on an off-centre process✓ Cp is only the best you could doCp ignores where the mean sits. A process can show Cp = 2 and still makescrap if it is centred hard against one limit. Cpk is the honest number.Both assume a stable, roughly normal process. Check a control chartfor stability before quoting either.Process Capabilitylearnposters.com
Process Capability — printable engineering wall chart from LearnPosters. Free vector PDF, US Letter and A4.

What’s on the Process Capability poster

The rule, 3 worked examples, and the mistake everyone makes.

Both assume a stable, roughly normal process. Check a control chart for stability before quoting either.

Questions about the Process Capability poster

What’s on the Process Capability poster?
The rule, 3 worked examples, and the mistake everyone makes. Capability compares the tolerance width with the process spread, and Cpk also account…; Cp = (USL − LSL) ÷ 6σ · Cpk = nearest gap ÷ 3σ; Tolerance ±0.1, σ = 0.02 = Cp = 1.67; Mean drifts 0.04 off = Cpk falls to 1.0; Cpk = 1.33 = About 63 parts per million; Common mistake: Reporting Cp on an off-centre process → Cp is only the best you could do. Both assume a stable, roughly normal process. Check a control chart for stability before quoting either.
Who is the Process Capability poster for?
Process Capability belongs to the Mechanical Engineering section rather than to a school year, because engineering is not something one grade owns. Anyone learning manufacturing can pin it up — a beginner, a student mid-course, or someone revising years later.
When should you use the Process Capability poster?
Reviewing production data, or deciding whether a tolerance is achievable. A wall chart earns its place by being glanceable from where the work is happening, so Process Capability belongs on the wall where that engineering work actually happens, within glancing distance, rather than filed away.
What other posters go with Process Capability?
Additive Processes, Casting Processes and Speed & Feed sit alongside Process Capability in the Mechanical Engineering section. Printed together they make a wall rather than a single sheet, which is how a reference set actually gets used.Additive ProcessesCasting ProcessesSpeed & Feed
Is the Process Capability poster free to download and print?
Yes. Process Capability downloads as a free PDF with no account, no email and no watermark, like everything else in the Mechanical Engineering section. Print as many copies as you like for a home, a classroom, a library or a tutoring group; reselling the file is the only thing the licence rules out.Read the licence
What size does the Process Capability poster print at?
Process Capability is a vector PDF laid out for US Letter, and prints on A4 with Fit to page — the same file, no separate download. Because every mark on it is drawn rather than photographed, it stays sharp enlarged to A3, A2 or A1 at a copy shop. Colour carries emphasis only, so a greyscale print of Process Capability loses nothing.Printing guide

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