Item Quality Analysis

Standard Filters

  • Company
  • Year
  • Quality Order Inspection Origin
  • Item
  • Business Partner
  • Inspection Test Result

Dashboard

The Item Quality Analysis dashboard lists the aggregated inspection results for each aspect characteristic combination of the selected inspection order. Specifically, the norm/nominal values, the upper and lower level warning limits, the upper and lower limits and the calculated mean value are displayed.

For each aspect/characteristic combination, these analysis criteria are reported:

  • Process Capability (Cp)
  • Process Capability Index Cpk)
  • Process Performance (Pp)
  • Process Performance Index (Ppk). A Ppk of 1 means the process is exactly centered.

Aspect/Characteristic Alerting Categories

  • Pass (green) relates to characteristics for which the measured value is between the upper and lower control limits
  • Intermediate (yellow) relates to characteristics for which the measured value is between the upper and lower warning limits and the upper and lower control limits
  • Fail (red) relates to characteristics for which the measured value is outside the upper and lower control limits.

Process Capability and Process Capability Index Calculations

The Process Capability (Cp) allows users to find the measurable properties of a process against a specification. The Process Capability Index (Cpk) shows users how well a process can perform against the specification.

Process Capability (Cp) formula
Upper Specification Limit (USL) - Lower Specification Limit (LSL) / 6 * Standard Deviation.
Process Capability Index (Cpk) formula
The minimum of USL - the mean / 3 * Standard Deviation, or the mean - LSL / 3 * Standard Deviation.
USL (Upper Control Limit) 49
LSL (Lower Control Limit) 39
Standard Deviation 2
Mean of Measurements 40
Process Capability (Cp)
The outcome is .833, which is calculated as follows:

= (49 – 39) / (6 * 2)

= 10 / 12

= 0.833

Process Capability Index (Cpk)
The outcome is .166, which is calculated as follows:
Solution 1

= (49 – 40) / (3 * 2)

= 1.5

Solution 2

= (40 – 39) / (3 * 2)

= .166

The minimum value between solution 1 (1.5) and solution 2 (.166) is .166.

Process Performance Process Performance Index Calculations

The Process Performance (Pp) allows users to decide if a process performs correctly within a certain period of time and against the specification. The Process Performance Index (Ppk) shows users how well a process can create a product that meets the specification.

Process Capability (Pp) formula
Upper Specification Limit (USL) - Lower Specification Limit (LSL) / 6 * Standard Deviation.
Process Capability Index (Ppk) formula
The minimum of USL - the process midpoint / 3 * Standard Deviation, or the process midpoint - LSL / 3 time * Standard Deviation.
USL (Upper Control Limit) 49
LSL (Lower Control Limit) 38
Standard Deviation 2
Process Midpoint (49 + 38) / 2 = 43.5
Process Performance (Pp)
The outcome is .917, which is calculated as follows:

= (49 – 38) / (6 * 2)

= 9 / 12

= 0.917

Process Performance Index (Ppk)
The outcome is .917, which is calculated as follows:
Solution 1

= (49 – 43.5) / (3 * 2)

= 0.917

Solution 2

= (43.5 – 38) / (3 * 2)

= .917

The minimum value between solution 1 (.917) and solution 2 (.917) is .917.