X̄-R · X̄-S · I-MR Limits locked at baseline, never silently recomputed

From messy Excels to live control charts in a minute

Upload your quality exports, map two columns, and get charts your auditor can check. Nelson rules fire the moment the process drifts — not three shifts later when someone reopens the workbook.

Shaft diameter — X̄ chart

Plant 1 · Shaft line A · n=5 · mm
3 points out of control demo data
Cp
1.62
Cpk
1.09
Rules tripped
1, 3
Limits locked
v2 · 14 Jul

The upward drift at the right tips over the locked limit. A spreadsheet chart that recalculates its limits with every new point would have absorbed that drift and shown a process in control.

One screen for the whole line

Every characteristic on the line, judged against its own locked limits. Put it on a shop-floor display with a read-only link — no login, refreshes itself.

Value in 60 seconds

Upload a CSV, map two columns, get a working control chart. No consultants, no six-week rollout, no IT ticket.

Forgiving CSV import

Decimal commas, semicolons, odd date formats, blank rows and extra columns parse on the first try. Bad mapping? Fix it and re-parse — no re-upload.

Shop-floor ready

Share any dashboard as a read-only link and put it full-screen on a factory display. Auto-refreshing, glanceable, no login.

How it works

01

Upload or connect

Drop in the CSV your CMM or gauge already spits out. Machines and scripts can post straight to the token-authenticated API instead.

02

Baseline your limits

Pick the window that represents a stable process, compute limits from it, and lock them. Re-baselining is a deliberate act with full version history.

03

Watch, share, act

New data is judged against the locked limits as it arrives. Out-of-control points flag themselves on the line display and at the manager's desk alike.

The charts you actually run

Control chart constants, limit formulas, Cp/Cpk and all eight Nelson rules are tested against worked examples with published answers.

X̄-R

subgroups of 2–10

The default for a gauge that measures a handful of parts per subgroup. Mean chart over range chart, both against locked limits.

X̄-S

subgroups of 10+

Larger subgroups where the standard deviation carries more information than the range.

I-MR

individuals

One reading at a time — bath temperature, batch assay, anything you can only measure once.

p and np

attributes

Fraction and count defective, with limits that follow varying lot size.

c and u

defect counts

Defects per unit or per area, for weld and surface inspection.

CUSUM and EWMA

small shifts

Catches slow drift a Shewhart chart needs many subgroups to confirm.

Gets data out of wherever it lives

No IT project. Start with the export you already have and move to a live feed when you're ready.

CSVGauge, CMM and lab exports. Re-map columns and re-parse without re-uploading.
PLCOPC UA and Modbus tags via a small on-prem collector.
MESPer-characteristic tokens so a line's system only writes its own data.
ERPPull part numbers and tolerances so nominal, USL and LSL stay in sync.
POST a subgroup from the line
curl -X POST https://api.spcvisuals.com/v1/measurements \
-H "Authorization: Bearer spc_live_..." \
-d '{"characteristic":"shaft-diameter",
"readings":[25.004,24.998,25.011,25.006,25.001],
"measured_at":"2026-08-14T06:40:00Z"}'

201 Created
{ "subgroup": 156, "xbar": 25.004,
"in_control": false, "rules": [1, 3] }

Evidence, not screenshots

When an auditor asks why a point passed, the answer is in the record: which limit set judged it, who locked that set, and when. Nothing is recomputed behind your back.

Versioned control limits

Every limit set is kept with its baseline window, author and timestamp.

Audit trail on every change

Tolerance edits, re-baselines and deletions are logged and exportable.

Validation pack

IQ/OQ templates plus the test results for the calculation engine, mapped to the textbook datasets they reproduce.

Tenant isolation and SSO

EU hosting, per-site roles, SAML on the plant plan.

What earlier detection is worth

Most of the cost of a drifting process is the parts you keep making before anyone notices. Move the sliders to your own numbers.

$900,000
30%
4 shifts

Assumes live charting cuts the lag to half a shift and that scrap from late-caught drift scales with the lag. Rough by design — bring your own numbers to the demo.

Avoidable scrap per year
$236,250

Drift-related scrap today$270,000
Lag after live charting0.5 shifts
Plant plan, 4 lines$14,400
Walk through your numbers

Pricing

Priced per line, not per seat. Everyone on the shop floor can look at a chart for free.

Line
One production line, one site.
$180/mo

  • Up to 25 characteristics
  • CSV import and REST API
  • Locked, versioned limits
  • Unlimited shop-floor viewers
Start a trial
Group
Several plants, one quality org.
Talk to us

  • Cross-site comparison views
  • Central limit governance
  • On-prem or private cloud
  • Custom data residency
Contact sales

Questions we get

Do we have to change how the line records data?

No. Start with the export you already produce. Most customers stay on CSV for months before wiring up the API.

What happens when the process legitimately changes?

You re-baseline deliberately. The old limit set stays on record with the points it judged, so history stays readable.

Can operators break something?

Shop-floor links are read-only and need no login. Editing limits and tolerances is a role you grant.

Is the math verifiable?

Yes. The engine is tested against published worked examples, and every chart shows the limit set and baseline window it used.

Where does our data sit?

EU hosting by default, isolated per tenant. Private cloud and on-prem are available on the Group plan.

How long does onboarding take?

First chart in the demo call. A full line, with limits baselined and a display in the hall, usually inside a week.

Bring one CSV. Leave with a working chart.

Twenty minutes, screen shared, your own data. If the limits don't match what your quality engineer computes by hand, we'll say so on the call.

No slides No procurement Data deleted after, on request