Show the distribution of a measured value against its specification limits, with Cp and Cpk.

Reference → Controls → Charts → HistogramChart


Available from FrameworX 10.1.6.

The HistogramChart is a process-capability histogram: it groups the samples of a measured characteristic into bins, draws the lower and upper specification limits (LSL, USL) and the target, overlays a normal curve and computes the capability indices Cp and Cpk (and optionally Pp and Ppk).


Requirements

This component is Portable. It runs both on Windows and on Web Pages hosted on any platform.

Clients: works in the Rich Client and in the web client (HTML5), with the same values and layout on both. Verified on FrameworX 10.1.6.


Configuration

  1. Go to Displays / Draw.
  2. In the Components Panel, select Charts, then choose HistogramChart.
  3. Click or drag-and-drop the component into the drawing area.
  4. Double-click the object to open the configuration window.

Data Binding

  • Live mode (default): bind LinkedValue to a tag. The chart keeps the newest SampleSize value changes.

  • Table mode: set UseDataTable to true and point DataSourceLink to a Dataset query or table (@Dataset.Query.Name / @Dataset.Table.Name) or a tag that holds a DataTable (@Tag.Name). ValueColumn names the column of samples.

  • LowerSpecLimitLink, UpperSpecLimitLink and TargetValueLink (a number or a tag) draw the LSL, USL and Target lines.

Behavior

  • Bins have equal width. BinCount 0 chooses the number of bins automatically (Sturges rule, 5 to 30). With UseFixedRange, the bins cover RangeMinimum to RangeMaximum and values outside are counted separately.

  • Cp and Cpk use the within-subgroup sigma (average moving range / 1.128): Cp = (USL − LSL) / 6σ and Cpk = min(USL − mean, mean − LSL) / 3σ. With only one limit set, Cpk uses that side.

  • With ShowPp, Pp and Ppk are computed in the same way with the overall sample standard deviation (n − 1).

  • ShowNormalCurve overlays the normal curve of the mean and the overall standard deviation.

  • Capability needs at least 2 samples and at least one specification limit; otherwise the chart shows a message instead of the indices.

Properties

Property

Description

Default

LinkedValue

Live mode: the measured value.

(empty)

UseDataTable

Read the samples from a table instead of sampling LinkedValue.

false

DataSourceLink

Table mode: the data source (Dataset query or table, or a DataTable tag).

(empty)

ValueColumn

Table mode: column that holds the samples.

Value

SampleSize

Live mode: number of newest samples kept.

100

BinCount

Number of bins; 0 for automatic.

0

UseFixedRange

Use a fixed range (RangeMinimum to RangeMaximum) for the bins.

false

RangeMinimum

Start of the fixed range.

0

RangeMaximum

End of the fixed range.

100

LowerSpecLimitLink

Lower specification limit (LSL), a number or a tag.

(empty)

UpperSpecLimitLink

Upper specification limit (USL), a number or a tag.

(empty)

TargetValueLink

Target value, a number or a tag.

(empty)

ShowNormalCurve

Overlay the normal curve.

true

ShowCapability

Show the statistics text (n, mean, Cp, Cpk).

true

ShowPp

Also show Pp and Ppk.

false

ShowAxisLabels

Show the axis labels.

true

Decimals

Number of decimals of the mean and sigma in the statistics text.

3

CurveStrokeThickness

Thickness of the normal curve.

2

LabelFontSize

Font size of the labels.

11

LabelFontFamily

Font family of the labels.

Verdana

Colors follow the Display theme by default: each color property has a theme slot. Set an explicit color (#AARRGGBB) only to override the theme. Color properties: BarFill (theme accent), CurveStroke (theme amber), SpecLimitStroke, TargetStroke, GridStroke and LabelForeground.


Example

Twenty measurements of a part dimension in table mode, with LowerSpecLimitLink 9, UpperSpecLimitLink 11, TargetValueLink 10, ShowPp true and Decimals 4. The chart shows:

Statistic

Value

n

20

Mean

10.0405

Cp / Cpk

1.21 / 1.16 (within σ 0.2758)

Pp / Ppk

1.52 / 1.45 (overall σ 0.2199)

Bins (automatic)

6 bins with 2, 3, 6, 4, 3 and 2 samples

The x axis runs from LSL (9.0) to USL (11.0), with the Target line at 10.0 and the normal curve over the bars.


Runtime Execution

At runtime the HistogramChart recomputes the bins and the indices as new samples arrive or the table changes. The image shows the example above in the Rich Client; the web client shows the same values.


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