Control Charts
The Control Charts page is used to display and compare measurement charts for selected parts and features.
Click a measurement point on a control chart to view its details.
Options
Recalculate Control Limits - Estimate a feature's control limits, starting from the selected measurement and ending after a set number of measurements (default: 25).
The Upper Control Limit (UCL) and Lower Control Limit (LCL) are static values calculated from a feature’s first 25 measurements. The Recalculate Control Limits button resets these values and recalculates them from the 25 measurements following the selected measurement.
Exclude Point - Do not consider this measurement when calculating a feature's control limits or SPC values (such as Real CPK).
Filters
Single Feature / Multi Feature - Toggle between showing a single feature's control charts, or multiple features' individual charts.
IX / Moving Range - Types of charts displayed on the page. Select from Individual and Moving Range charts.
Internal/Supplier - Toggles the Part Number filter between showing your account's parts (Internal) and your suppliers' parts (Supplier).
Supplier - Name of a part's supplier.
Part Number - Number corresponding with a part record.
Feature Number (or Features) - Number corresponding with the feature on the selected Part Number's inspection plan. If "Multi Feature" is toggled, then multiple feature numbers can be selected.
Range - Selection of measurements displayed on the control chart. If "Run Number" is selected, then one or more run numbers must be selected from the Runs filter.
Number of Points - Number of measurements to display on the control chart(s).
Runs - Run number(s) to be shown on the control chart(s).
Summary Data and other capability information
“Static CpK" and "Static CP" are initially calculated using the feature’s first 20 measurements by default and are not affected by further measurements. These values can be recalculated at any point from another set of 20 measurements chosen by a user.
“Real CPK and "Real CP" are calculated from a feature’s most recent 20 measurements by default and are continually updated as additional measurements are recorded.
USL = upper specification limit
LSL = lower specification limit
σ = process variability (standard deviation)
μ = process mean
UCL = Upper control limit
LCL = Lower control limit
CPK: min(CpU,CpL)
CPU: (USL - μ) / 3σ
CPL: (μ - LSL) / 3σ
CP: (USL - LSL) / 6σ
UCL: μ + 3σ
LCL: μ - 3σ
Moving Range Chart
The moving range control limit is calculated based on the following formula. But note, this value is not currently being displayed or used by the software for out-of-control notifications.
UCL = [Average] * 3.267
[Average] is calculated by averaging all of the ranges in a defined set. Each range shown on the Moving Range chart is calculated from 2 consecutive measurements.
Each point is the difference between two consecutive measurement points in the top chart.
Add to Favorites
To add a custom chart to your dashboard, please see Adding to Favorites.