SAP QM SPC: control charts, Cpk and stability studies
sap qm spc
Also searched as
- sap qm stability study
- sap qm control chart QGC1 QGC2
- sap qm cpk process capability
Short answer
SAP QM supports statistical process control through quality control charts, created in QGC1 and evaluated with QGC2, fed by quantitative results recorded in inspection lots. Cpk and process capability indices are calculated from those results. Stability studies are a separate, time-based sampling function used mainly in regulated industries.
Applies to: SAP ECC 6.0 and S/4HANA on-premise; stability study availability depends on release and industry solution
Set up SPC for a characteristic
- 1Make sure the characteristic is quantitative and recorded with results in the inspection plan (QP01) with a target and both tolerance limits. Qualitative characteristics cannot feed a control chart.
- 2Set the sample size so each inspection lot gives a subgroup, for example 5 samples recorded per lot, so range and standard deviation charts are meaningful.
- 3Record results in QE01 or QE51N on released lots so values exist in QAMR. Without results there is nothing to plot.
- 4Open QGC1 to create a control chart. Select the characteristic, plant and material, the chart type (for example mean and standard deviation, or mean and range) and the evaluation period.
- 5Set or calculate the control limits. You can derive them from the data or enter fixed limits from a capability study.
- 6Evaluate with QGC2. Review points outside control limits and the run rules you have configured, and open the underlying lots from the chart to see what happened.
- 7Read the Cpk and Cp values from the capability evaluation and compare them with the customer requirement, commonly Cpk of 1.33 or higher for stable processes, but follow your customer specification.
Data you need before SPC works
SPC in SAP is only as good as the recorded data. The results must be numeric, recorded per sample or as a mean per lot, and attributed to the correct characteristic and lot. If operators record only pass or fail, you will see no meaningful chart.
For continuous production, collect results at the operation by production inspection type 03 or by in-process inspection points. For goods receipt, remember that each lot is a different delivery, so a chart across vendors mixes populations; chart by vendor to get meaningful limits.
Control charts and capability
A control chart plots the subgroup statistic against upper and lower control limits calculated at three standard deviations around the mean. Tolerance limits come from the specification, control limits from the process. The two are different, and a process can be in control yet out of specification, which is exactly what Cp and Cpk expose.
Cp compares tolerance width to process spread. Cpk also accounts for how well centred the process is. Report both, and record the sample basis: Cpk from 30 values is much less reliable than from 300. When customers ask for PPAP or an initial process study, document the sample plan and the period alongside the figure.
Stability studies
A stability study answers a different question: how does a product behave over time under defined storage conditions. It plans samples to be drawn and tested at scheduled intervals and compares results to specification limits across time points. It is typical in pharmaceuticals and food, and is delivered as part of the QM functionality for those uses, with its own master data for study design and time points.
Menu paths and transaction codes for stability studies vary by release and by whether the industry extension is active. Check Quality Management in your SAP menu for the stability study functions rather than relying on a single code, and confirm with your QM consultant whether it is licensed and activated in your system.
When SAP SPC is not enough
SAP's standard SPC covers the common charts but not advanced capability analysis, multivariate charts or real-time machine data. Many plants pass inspection results to a dedicated SPC tool or a quality management system. If so, define what moves where: the lot and characteristic keys from QALS and QAMV are the join keys. Do not duplicate recording in two systems.
Try it here, free
SAP QM Process Capability Cp Cpk Calculator
Turn spec limits, mean and sigma from recorded inspection results into Cp, Cpk and expected PPM.
Common pitfalls
- !Charting qualitative data or mixed units on one chart.
- !Using tolerance limits as control limits, which hides drift until parts fail.
- !Charting across vendors or tools without stratifying, which inflates the spread.
- !Calculating Cpk on too few values and reporting it as a precise figure.
- !Assuming the stability study menu is active in every system; it may not be.
How an ERP-grounded AI assistant handles this
For SPC questions a grounded assistant can pull the quantitative results for a characteristic from QAMR, compute mean, standard deviation and a Cpk estimate, and flag points that break a chosen rule, showing the lots behind each point. On-prem deployment keeps quality data inside your network. It supports analysis; your quality engineer remains responsible for the capability claim.
Frequently asked questions
What transactions are used for SPC in SAP QM?
QGC1 creates a quality control chart and QGC2 evaluates it. Both draw on quantitative results recorded in inspection lots. Capability indices such as Cp and Cpk are available in the evaluation of those results.
Can SAP QM calculate Cpk?
Yes, process capability indices can be evaluated from recorded quantitative results, subject to enough data and correct target and tolerance values. For advanced capability analysis many companies export the data to a specialised statistical tool.
What is an SAP QM stability study?
It is a time-based study that schedules sampling and testing of a product at defined intervals under storage conditions, mainly in regulated industries. It is separate from SPC control charts, which monitor process variation lot by lot.
Why is my control chart empty?
Usually the characteristic is qualitative, results were not saved on released lots, or the selection does not match the material, plant and period. Check QAMR for the characteristic, then widen the selection.
Related
SAP QM inspection results report: which tcode shows what
Use QA32 for the list of inspection lots, QE51N or QE03 for recorded results, the QM information system (for example QM12) and QGC2 for evaluations of characteristics over time, and QA11 or QAVE for usage decisions. If none fits, read the tables QALS, QAMV, QAMR and QAVE directly.
How-toHow to create an inspection plan in SAP QM (QP01)
Use QP01 to create the plan: enter the material and plant, fill the header (usage, status), add an operation with a work center, assign inspection characteristics, set the sampling procedure and save. The plan is only found at goods receipt when it is assigned to the material and the material has an active inspection type.
How-toSAP QA11 Usage Decision: Make It and Post Stock Correctly
The usage decision (UD) in QA11 closes an inspection lot, assigns a quality score and a UD code such as accepted or rejected, and posts the lot quantity from quality inspection stock to unrestricted use, blocked stock, scrap or return to vendor. The UD is blocked until required inspection characteristics are closed and results are recorded.
How-toGauge Found Out of Tolerance: How to Find Affected Product Using ERP and Calibration Data
When a calibration finds a gauge out of tolerance, you must assess every product it measured since its last in-tolerance calibration. That is only possible if inspection records carry the gauge ID. Record the gauge on each inspection result, then query by gauge and date window to list lots, jobs and shipments, and raise NCRs for any that are doubtful.
Error fixSAP M7 021: Deficit of SL Stock Quantity
M7 021 fires during a goods issue, delivery, or confirmation when SAP checks the unrestricted-use (SL) stock for the exact plant, storage location and batch combination and finds less than what you are trying to post out. Fix the entry (batch, storage location, quantity) first; only enable negative stock or downgrade the message to a warning if the business genuinely needs to post ahead of a receipt.
Error fixSAP IDoc Status 51: Application Document Not Posted
Status 51 tells you the IDoc reached the application layer and failed to post, but the status text itself is not the error - the real cause sits in the status record's long text or the linked application log. Fix the underlying data or configuration, then reprocess the IDoc through BD87 rather than editing the status.
AI for ERPAI for SAP Quality Management: Notifications, 8D, and CAPA Without the Manual Drafting
AI grounded on SAP QM data that triages notifications, drafts 8D and CAPA reports, and summarizes inspection trends, deployed on-prem for full traceability.
Stuck on SAP ECC / S/4HANA?
Talk to engineers who work inside SAP ECC / S/4HANA every week, and who build private AI that answers these questions from your own ERP data.
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Free tools
- SAP QM Process Capability Cp Cpk CalculatorTurn spec limits, mean and sigma from recorded inspection results into Cp, Cpk and expected PPM.
- SAP QM Cp and Cpk Capability CalculatorEnter the mean, standard deviation and specification limits of a quantitative characteristic and get Cp, Cpk and the expected parts per million out of tolerance.
- SAP QM in Procurement Setup ChecklistCheck each step needed to run goods receipt inspection for purchased materials, from QM control key to vendor release.
ERP fixes and how-tos
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- SAP Error: Define QM Procurement Key (How to Fix It)Fix the SAP QM procurement key error: define the key in the QM in Procurement IMG, activate QM at plant level, and set QM proc. active and the control key in the material master.
- SAP QM inspection results report: which tcode shows whatFind inspection results in SAP QM: QA32 lot list, QE51N results worklist, QM12 and QGC2 evaluations, MIC history, and the QALS, QAMR and QAVE tables.
Guides
- SPC Integration with ERP Quality Modules: Closing the Loop Between Control Charts and Quality RecordsSPC integration with ERP quality modules: control charts, Cpk data flow, AS9100D compliance, SyteLine and LN quality setup, and AI-driven quality automation.
- SyteLine Statistical Process Control (SPC) Implementation GuideImplement statistical process control in SyteLine for manufacturing quality. Configure control charts, Cpk calculations, and process monitoring in CloudSuite Industrial.
AI on your ERP
- AI for InfinityQS SPC: Explain Out-of-Control Signals Using ERP Lots, Orders and SuppliersPrivate AI for InfinityQS SPC data joined to ERP lots, orders and suppliers. Explain out-of-control signals, Cpk drift and containment with sources shown.
- AI for SAP Quality Management: Notifications, 8D, and CAPA Without the Manual DraftingAI grounded on SAP QM data that triages notifications, drafts 8D and CAPA reports, and summarizes inspection trends, deployed on-prem for full traceability.