Data for Tolerancing Procedure
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Required data

The tolerancing procedure uses two dialog boxes: Calculate Gap Pools and Allocate Gap Pools. To begin the procedure, the worksheet must contain these columns:

·    Means of each element in the assembly. All values must be positive.

·    Standard deviations of each element in the assembly. All values must be greater than or equal to 0. The sum of the variances (standard deviation squared) must be greater than 0.

·    Directional vectors for each element in the assembly. For elements that add to the gap width, enter a 1. For elements that subtract from the gap width, enter a -1.

Use Six Sigma > Create Template to create a worksheet for entering tolerancing data.

The only missing values allowed are standard deviations.

To complete the procedure using Allocate Gap Pools, you must enter one or two columns of allocation weights. The allocation weights you enter depend on the output from the first part of the command. The weights must be all positive numbers from 0 to 1, and the sum of each column must be equal to 1. See Brake Assembly Example, Part II for an illustration of designating allocation weights.

Optional data

You can include columns containing the following information:

Element names

If you don't enter this column, the defaults are Element 1, Element 2, etc.

Complexities

Number of times each particular element occurs. The values you enter must all be positive integers.

Lower specification limits

If you don't enter this column, Minitab uses the initial nominal - 4.6505 times the initial long-term standard deviation for each element.

Initial nominal specifications

If you don't enter this column, Minitab uses the initial element means as the nominal specifications when calculating the initial default upper and lower specification limits.

Upper specification limits

If you don't enter this column, Minitab uses the initial nominal + 4.6505 times the initial long-term standard deviation for each element.

Diametrical correction factors

Can be either 0.5 or 1.0. By default, this value is set to 1 for each element.

Shift factors

Reflect the size and direction of the shift from the mean. Values must be between -20 and 20. The default is 1.5. A value of 2, for instance, means the element's mean shifts 2s. Positive values shift the mean in a positive direction; negative values shift the mean in a negative direction, relative to the gap.

Drift factors

Ratios between the long-term and short-term standard deviations. The values must be greater than or equal to 1. The default drift factor is 1.8.

Number of standard deviations

Use for defining the upper and lower specifications. The default value is 4.6505, and says to set the specifications at the nominal + 4.6505 times the long-term standard deviation.