Process specifications for Short Run

A process specification is very similar to a standard, but it defines the combination of process + characteristic instead of part number + characteristic.

You can set up Short Run process specifications in several places:

• For instructions beginning with the Administration module, click here:

  1. Navigate to the Configurations tab in the Administration module.

  2. Expand the Configurations tree (if needed).

  3. For the configuration you want to change, expand the tree.

  

  4. Expand the Lists, Standards, and Tables tree.

  5. Expand the SPC tree.

  6. Right-click the Processes node on this tree.

  If you have changed some configuration settings but not yet saved them, you will be prompted to save or cancel your changes before continuing.

  7. If multiple indexes have been defined, or if GainSeeker runs on a SQL Server, Oracle, or MySQL database, you will be prompted to choose the traceability field for which to set up process specifications:

  

• For instructions beginning with the GainSeeker Charts, GainSeeker Inspections, PC Collect, SPC Data Entry, or legacy SPC Charts and Reports module, click here:

  1. Launch the GainSeeker Charts, GainSeeker Inspections, PC Collect, SPC Data Entry, or legacy SPC Charts and Reports module.

  2. Click the Setup menu.
     In the GainSeeker Charts, GainSeeker Inspections, PC Collect, point to Standards.

  3. Then click SPC Process Specs.

  4. If multiple indexes have been defined, or if GainSeeker runs on a SQL Server, Oracle, or MySQL database, you will be prompted to choose the traceability field for which to set up process specifications:

  

To enter a new process specification:

1. Click New. Enter a name for the new process specification, and then click OK.

Best practice is to specify a combination of process name and characteristic being measured. For example: if multiple part numbers are modified by the CUTOFF process and are routinely sampled for length and weight, then you should create one process specification for CUTOFF LENGTH and a second process specification for CUTOFF WEIGHT.

2. Specify all desired settings for the process specification, and then click OK.

Almost all of the settings on the Process Spec Information screen are identical to the settings for standards. The two settings that are different are found on the General tab:

1. • Add to traceability list

Selecting this check box will add this item to the predefined list for this traceability field. This makes it easy to select the correct process specification during data entry or while setting up a planned session.

1. • Short Run method

Select the method of Short Run calculations to use for this process. Your choices are:

1. 1. • Target/Nominal:  This subtracts the target or nominal dimension from the chart plot point. Target/Nominal assumes a constant subgroup size, and the variability of each process is not significantly different.

      • Range/Short Run:  Range/Short Run codes measurements by variability (range values). This subtracts the target value from the plot point, but also divides the coded value and R value by the variance factor (target R or s). This method requires uniform subgroup sizes across part numbers. The center line for the chart will be zero. The center line for the R chart will be one. The control limits for and R charts are plus/minus factors.

This is useful when the specification width from product to product is significant. The Range/Short Run method uses the range values from the Standard to factor out the difference from product to product.

1. 1. • Standardized:  Values are plotted as expressions of standard deviation. Standardized charts subtract a constant from the plot point and divide that value by the variance factor. The center line of the chart will always be zero, and the control limits will always be placed at plus or minus three standard deviations. Variance and sample size may vary.

The Standardized method uses the target range value from the Standard to factor out the difference from product to product.

1. 1. • Uncoded:  Functions as a conventional SPC program. The data is displayed as actual values. Dimension and variation must be identical or statistics will not be valid.

During data entry, almost all of the settings from the process specification will be used instead of the settings from the standard. The only settings that will be used from the standard are:

• • Subgroup size  

  • Data entry constant  

  • Target X (for coding the data values on Target/Nominal, Range/Short Run and Standardized short run charts)

  • Target R (for coding the data values on Range/Short Run and Standardized short run charts)

This means that for all data entered in Short Run mode:

• • the Decimal places setting in the process specification will be used to display data values.

If different part numbers will measure this characteristic with different numbers of decimal places, then you should configure this process specification with the largest number of decimal places that will be needed to display this characteristic.

• • the settings for Reasonable limits, Write to monitor tables, Real-time checks, and all Specs, Gates and Ind. Gates will come from the process specification instead of the standard.

Additionally:

• • If you plan to report a ProcessCpk, you should enter coded Spec limits on the Limit X tab of the process specification.

  • It is not necessary to store historical control limits as Gate limits for Standardized short run charts. On this type of chart, the Upper Control Limit on X-bar charts and on Range charts is always 3, and the Lower Control Limit on both charts is always -3.