WI-130 SPC System

This program allows the operator to weigh a specified number of samples using a specified target weight. The program will print the sample weights and provide analysis of the samples. The program utilizes a WI-130 scale indicator and a WP-234 printer.

Before samples are weighed, the system parameters must be set by selecting the PARMS key. This does not, however, need to be done every time a sample is to be taken.

After entering the appropriate password, the program prompts the operator to set the printer. If 'Yes' is selected, the printer will print after each sample is weighed. If 'No' is selected, the printer will print after all samples are weighed.

The program will then prompt the operator to choose between allowing the program to store the weight of each sample automatically, or to allow the operator to control when the weight is stored. Select 'No' to let the system automatically store the weight. Select 'Yes' to let the operator control this step.

Finally, the operator must enter the threshold weight. This number is the amount of weight the system uses in capturing a stable weight.

To begin the test, press the TEST key. Enter the target weight, the over and under tolerance weights, and the desired sample size. Then begin weighing samples.

When the selected sample size is reached, the following statistical information will print.

The value of each weighment

The over tolerance

The under tolerance

The accept value

The number of weights over tolerance

The number of weights under tolerance

The number of weights within tolerance

The average weight

The highest value

The lowest value

The standard deviation

The coefficient of variance

The number of samples taken

Calculating Statistical Values in the WI-130

The program described in this issue utilizes a function, provided by the WI-130 BASIC command set, that automatically calculates certain statistical values.

The command is CALCSTAT, and the results are based on a series of numbers provided as parameters for the command.

The command requires a starting memory location for the series of values to be used in the calculation, the number of memory locations to be used, from the previous starting location, and a starting memory location for the destination of the statistical results.

The following results are calculated: Average, Minimum, Maximum, Average Deviation, Standard Deviation, Standard Variance, Skewness, and Curtosis.