Control chart software that starts from a paste.
Paste readings from Excel or your CMM into the box. Cpkboard draws the X-bar and R chart with control limits from your data, marks the Western Electric rule violations in red, and shows Cp, Cpk, Pp and Ppk against your spec. Then it does the same for every feature in your shop, on one board.
125 readings in 25 subgroups. Nothing you paste here leaves your browser.
- Rule 1 Point 19 is beyond a control limit
- Rule 2 2 of 3 points beyond 2 sigma, at point 19
- Rule 3 4 of 5 points beyond 1 sigma, at point 21
The charts, and the constants behind them.
Shewhart charts as the AIAG SPC manual defines them. No decision tree to follow: pick the subgroup size and the right chart is used.
X-bar and R
Subgroups of 2 to 10 readings. Limits from A2, D3, D4; sigma from R-bar over d2.
X-bar and S
Subgroups over 10. Limits from A3, B3, B4; sigma from S-bar over c4.
Individuals and moving range
One reading at a time. Limits from 2.66 × MR-bar; sigma from MR-bar over 1.128.
p and np
Defective parts per sample, fixed or variable sample size.
c and u
Defects per unit, fixed or variable area of opportunity.
Histogram with spec limits
Bins against USL and LSL, out-of-spec readings in red, normal curve overlay.
Out of control is flagged, not left for you to spot.
Rule 1
One point beyond 3 sigma.
Rule 2
Two of three points beyond 2 sigma on the same side.
Rule 3
Four of five points beyond 1 sigma on the same side.
Rule 4
Eight points in a row on one side of the center line.
Nelson rules 5 to 8 can be switched on per feature. Rule violations show on the chart, on the feature board, and as an alert on the Pro plan.
Put your first feature on the board tonight.
Create your account in two minutes. Paste last week's readings or send us a CMM export, and the chart and Cpk your customer asked for are ready to send.