SPC software
Control charts in the browser, with the rules from the AIAG-VDA SPC manual
x̄-R, x̄-s and individuals charts for variable data, p, np, c and u for attribute data. my8data calculates control limits, marks rule violations and shows capability indices only once the chart is stable.
- Every chart type included in the free account
- No installation, servers in Germany
- Order on invoice, no credit card
Result
This is what the result looks like
x̄-R chart with 25 subgroups, calculated with sample data. From subgroup 19, 7 means lie above the centre line and rule 9 triggers. Because the proof of stability is missing, my8data reports Pp and Ppk, not Cp and Cpk.
Chart types
Seven control charts for variable and attribute data
Which chart fits depends on the kind of data and the subgroup size.
| Chart | Use |
|---|---|
| x̄-R | Variable data, subgroups of 2 to 10 parts |
| x̄-s | Variable data, subgroups of more than 10 parts |
| Individuals (I-MR) | One reading per point in time, with moving range |
| p | Proportion of defective parts, also with varying sample size |
| np | Number of defective parts with constant sample size |
| c | Number of defects per unit with constant inspection quantity |
| u | Defects per unit with varying inspection quantity |
Evaluation
What the chart tells you
The defaults are the rules from the AIAG-VDA SPC manual and ISO 7870-2: one point outside the control limits, 7 points on one side, 7 rises or falls in a row. Western Electric and Nelson rules can be added.
With these rules my8data matches the pattern tests of the reference data sets in ISO/TR 11462-3.
my8data calculates process performance from the standard deviation of all individual values, as the AIAG-VDA SPC manual and ISO 22514-2 require.
If the chart shows a rule violation, there is no proof of stability. my8data then reports no Cp and Cpk and says why.
Checked against reference values
The public validation report documents the reference data sets, target values and deviations achieved for the methods in my8data.
Pricing
Every method in every plan
All prices excl. VAT. 12-month term, cancellable with 30 days’ notice. Order by PDF form on invoice.
- All methods
- Unlimited calculations
- PDF and Excel export
- Save analyses
- Everything in FREE
- PDF report from your own Excel template
- Excel export with data and results
- Save and reopen analyses
- Personal support from the developer
- Everything in PRO, for every user
- Shared team storage
- Seats transferable when staff change
FAQ
Questions about the SPC software
Which rules does my8data check?
Rules 1, 9 and 10 from the AIAG-VDA SPC manual are the default. Western Electric and Nelson rules can be switched on one by one. The more rules are active, the more false alarms occur.
Why does my8data not always show a Cpk?
Cp and Cpk assume a stable process. If the chart violates a rule, my8data shows Pp and Ppk from the total variation and points out that the proof of stability is missing.
How do the readings get into the chart?
You type the values in or copy them from Excel or another spreadsheet into the input. You set the subgroup size beforehand.
Does my8data monitor production in real time?
No. my8data evaluates recorded readings. There is no connection to gauges and no data entry directly at the machine.
What does the SPC software cost?
All chart types are included in the free account. PDF and Excel export and saving cost €490 per user and year excl. VAT with PRO.
Check it with your own data
Create a free account, paste an existing data series and compare the chart with your current evaluation.