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SPC Statistical Process

SPC Statistical Process · Control Charts and CPK

Upgrade quality management from "firefighting after the fact" to "preventing within the process." Six chart types — Xbar-R, Xbar-S, P, NP, C and U — are plotted in real time, CPK / PPK process-capability indices are calculated automatically, the Nelson 8 out-of-control rules are detected automatically, and alerts fire before a deviation ever occurs.

6
Control-chart types
8
Nelson out-of-control rules
1.33
CPK target auto-tracked
Capabilities

Core Capabilities of the SPC Engine

From data capture and control-chart plotting to anomaly detection and a closed improvement loop

📈 Variable Control Charts

Xbar-R / Xbar-S / individual X-MR / median charts, for continuous variables such as dimension, weight and current.

📊 Attribute Control Charts

P / NP / C / U charts, for discrete data such as defect rate, defect count, number of defects and defects per unit.

📐 CPK / PPK Calculation

Process-capability indices are calculated automatically and compared in real time against customer baselines (1.33 / 1.67), with trends visible.

🚨 Nelson 8 Out-of-Control Rules

Automatic detection of 8 abnormal patterns such as 1 point beyond 3σ, 9 consecutive points on one side, and 6 consecutive increasing / decreasing points.

🔥 Real-Time Alerts

The moment an out-of-control point appears, it's pushed to PDA / DingTalk / WeCom, getting a quality engineer on-site within 5 minutes.

📝 Anomaly-Cause Logging

Once an anomaly is confirmed, log the cause with 5W2H, link it to an 8D improvement workflow, and close the PDCA loop.

mes.shangbangke.com/spc/collect3 channels
SPC
SPC Capture Channels
ConfigLive capture
ChannelSourceSubgrpStatus
PDAKey dims at reportingn=5Active
BluetoothDigital caliper readoutn=5Active
EquipmentCNC in-line measure pushn=3Live
SCADAInjection process paramsn=3Live

SPC Data Capture: Three Channels — Manual + Gauge + Equipment

The biggest pain in SPC isn't plotting — it's collecting data. SBK MES extends data sources to 3 channels: ① worker PDA reporting ② direct Bluetooth readout from gauges such as calipers, micrometers and height gauges ③ automatic push of PLC / SCADA equipment data.

  • Enter key dimensions during PDA reporting, automatically entering the SPC data pool
  • Bluetooth gauge direct readout: data goes from instrument to screen with zero delay and zero error
  • Automatic equipment-data push: CNC in-line measurement results enter SPC in real time
  • Subgroup size and sampling frequency are sampled automatically per process definition
mes.shangbangke.com/spc/cpkCapability
SPC
CPK Trend — OD Ø50
HistogramExport
1.52CPK
1.48PPK
1.33Baseline
0.011Sigma

CPK over last 8 periods

1.5W14
1.4W15
1.6W16
1.4W17
1.3W18
1.5W19

CPK Trend Dashboard: Process Capability at a Glance

Customer audits care most about whether CPK is stable and meets target. The system rolls up CPK by operation + critical characteristic, comparing the trend chart against the customer baseline (1.33 or 1.67), with an automatic alert when it falls below baseline for 3 consecutive periods.

  • Calculate CPK separately by operation + critical-characteristic dimension
  • Run short-term PPK and long-term CPK metrics in parallel
  • Three-in-one: trend chart + histogram + normality test
  • One-click export of customer audit reports (including data details + charts)
mes.shangbangke.com/spc/8d8D loop
SPC
Improvement Loop — Chart OOC
5W2HSubmit 8D
Contain D3
Quarantine 18 pcs · done
Cause D4
Tool wear · confirmed
Action D5
Shorten tool cycle 70%
Verify D6
Sampling verify 40%
Prevent D7
Capture into SOP

When Anomalies Occur: A Closed Loop from Alert to Improvement

When an anomaly alarm appears, the system doesn't just "beep" and move on — it triggers 5W2H cause logging, an 8D improvement workflow, effectiveness verification and mistake-proofing measures, for a complete PDCA loop.

  • Click an out-of-control point to pop up the 5W2H logging form
  • Linked 8D report workflow, including containment, cause and countermeasures
  • Verify effectiveness over N sampling points after countermeasures are implemented
  • Mistake-proofing measures are captured in the SOP, never to recur
Use Cases

SPC in Practice Across Industries

Auto Parts: Critical-Dimension CPK

IATF 16949 requires critical-characteristic CPK ≥ 1.67; the system auto-generates the PPAP report monthly.

Injection Process-Parameter SPC

Injection pressure / holding / mold temperature enter SPC in real time, warning of process drift before products go out of spec.

SMT Solder-Joint Yield P-Chart

Per-board solder-joint defect rate is plotted as a P-chart; 9 consecutive boards increasing triggers preventive maintenance.

Chemical pH Individual Chart

An individual-moving-range chart for batch pH automatically halts feeding before pH drifts to the customer limit.

Related Features

SPC Works Hand-in-Hand with These Capabilities

SPC is the quality brain — its data comes from inspection and reporting, and its results drive traceability and defect handling

Experience SPC Statistical Process Now

Sign up to try control charts and automatic CPK calculation for free, or book a consultant demo