USING THE COMPUTER: A FULL DESCRIPTION OF HOW TO USE MINITAB AND SPC WITH MACHINE ACCEPTANCE TYPE DATA

With the proliferation of computers, machine acceptance capability has become very simple. There are many software companies that provide a variety of software packages, and the majority of them do a very good job. However, for us to evaluate every one of them is beyond the scope of this chapter as well as this volume. We have decided to use two very common software products because of their ease and popularity ” especially in the automotive world. By using this software, we are not endorsing a particular product; rather, we are explaining their process for evaluating machine acceptance.

The following is a list and explanation of conventions used in this section: (1) all of the computer commands are listed in the left-hand column; explanations are in the right-hand column, directly across from the commands; (2) when a command is to be entered, the first column will say [command]. The command between the brackets should be typed in, then the Enter or Return key pressed. Note that DOS, Minitab, and SQC commands are not case sensitive; that is, the command [STOP] can also be entered [stop].

GETTING STARTED

First, set up Minitab and SQC on the hard drive.

To set up Minitab on the hard drive, follow these commands at the DOS prompt:
[CD\]	Puts the user in the root directory.
Insert the Minitab disk A or A\B in the floppy drive.
[A:]	Transfers computer control to drive A.
[MINSTALL]	Begins the Minitab install program.

Read all instructions on the screen carefully . Copy Minitab into a directory named Minitab on the hard drive of the computer. When the computer is finished copying Minitab Disk A, it will prompt you to insert Minitab Disk B. The process continues until all the disks have been copied onto the hard drive.

After all of the floppy disks have been copied onto the hard drive, try the following exercise to ensure that Minitab will work without flaws. If warning messages are encountered , consult the Minitab owner's manual.

[END]

Tells the Minitab software you are finished entering data.

The software will prompt '6 Rows Read'.

[Print C1-C2]

Tells Minitab to print Column 1 and Column 2 on the computer screen.

At this point check the 2 columns , 6 rows of data. The data should look like this:

ROW	C1	C2
1	1	2
2	3	4
3	5	6
4	3	4
5	2	5
6	3	4

Check the data for errors. The Minitab software allows many ways to edit data.

Consult the manual.

After the data have been checked and verified , the data file should be saved.

[SAVE "TEST" C1-C2]

Saves the minitab data file in file named TEST.MTW. The Minitab software will put an .MTW extension on the file automatically.

The software will prompt 'Worksheet saved into file: Test.MTW'.

Now that the data file is created and saved for Minitab, create an ASCII data file that the SQC software can read. Above, the Minitab data file was named TEST, the Minitab software put an .MTW extension on the file. Name the ASCII file TEST also; the following command will put a .DAT extension on the file.

MINITAB CHECK

[C:]	Puts control back to the hard drive.
[CD\Minitab]	Gets into the Minitab directory.
[Minitab]	Starts the Minitab software.
[Read C1 C2]	Tells the Minitab software you are going to enter two columns of data.
[1 2]	Minitab takes the value 1 and puts it in the 1st column and 1st row position. It also takes the value 2 and places it in the 2nd column, 1st row position.
[3 4]	Puts 3 in the 1st column, 2nd row position. Puts 4 in the 2nd column, 2nd row position
[5 6]	Puts 5 in the 1st column, 3rd row position. Puts 6 in the 2nd column, 3rd row position.
[3 4]	Puts 3 in the 1st column, 4th row position. Puts 4 in the 2nd column, 3rd row position.
[2 5]	Puts 2 in the 1st column, 5th row position. Puts 5 in the 2nd column, 4th row position.
[3 4]	Puts 3 in the 1st column, 6th row position. Puts 4 in the 2nd column, 6th row position.
[Write 'TEST' C1-C2]	Creates a data file named TEST.DAT that contains the data from Columns 1 and 2 in ASCII code.
[Stop]	Exits the Minitab software.

Now Minitab is loaded, checked, and ready to run. Do the same with the SQC software.

The second screen to appear is the main menu. It is where most of the commands that we need are located. The main menu looks like this:

Toggle variable/Attribute mode

Input data from a file

Transform the working data set

Toggle the capability flag

Formatted report (Stat + Hist)

Specification limits

Xbar chart

Range chart

Individual charts

Additional charts and graphs menu

Statistical parameters menu

Charting and graphing parameters menu

Clear and restart the SQC session

Route report output to file/printer

Execute an SQC command file

Terminate the SQC session

Hit RETURN to select item

Hit "?" for explanation of item

Hit RETURN to select item

Hit "?" for explanation of item

Data file:

LOADING SQC

When loading SQC, create a directory (off the root directory) in which to store the software programs. To do this:

[CD\]	Puts control back to the root directory.
[MD SQC]	Creates a directory called SQC.
[CD\SQC]	Puts control to the SQC directory.

Put the SQC floppy disk in the A: drive.

[Copy A:*.*]

Copies the program software into the SQC directory on the hard drive.

Once the floppy disk has been copied onto the hard drive, do the following exercise to ensure that SQC works. If warning messages are encountered consult the owner's manual.

[SQC]

Runs the SQC software.

The first screen states the software and developer's name.

Press Enter

Continue.

Using the up and down arrow keys, highlight the second line down 'Input data from a file'.

Press Enter

Allows data file input.

Input the data file made when checking the Minitab software. It is in the Minitab subdirectory. The following command will import the data from the Minitab subdirectory. At this time the software has prompted 'Enter data from'.

[C:\MINITAB\TEST.DAT]

Gets the ASCII data file created earlier by the Minitab software in the Minitab subdirectory.

The software will tell the number of lines read and will read the data file title if you have included one (see Using Edlin section). If there is no title, the software will say 'no title found'.

Press Enter	Returns to the Main Menu.
Highlight the 'Toggle the Capability Flag' line, press Enter	Tells the software to report Cp and Cpk values with the statistics block.
Enter the limit [1], Press Enter	The computer will prompt for the nominal value.
Enter the nominal blueprint value [3], press Enter	The computer will prompt for the upper limit.
Enter upper limit [5], press Enter	The computer will print the current specification limits.
Press Enter	Continue.
Highlight the 'Formatted Report (Stats + Hist)' line, press Enter	Prompts the software to display a statistics report and histogram.

The software will prompt for the group size .

Enter the group size [4], press Enter	The software displays the statistics report including the Cp and Cpk values.
Press Enter	A histogram of the data will scroll by on the screen.

If all appears correct in the stats block and histogram, then continue on. If entry problems occurred while in Minitab, they will also be present here. The SQC data file can be edited with EDLIN or any line editor software (to edit with Edlin you will need to terminate the SQC session). Assuming that all is correct, continue.

Highlight the 7th line down 'Xbar chart', press Enter	Displays an Xbar chart on the screen.
Press Enter	Continue.
Highlight the 8th line down 'Range chart', press Enter	Displays a Range chart on the screen.

If no unusual error messages appear while using the above commands then SQC should be operating properly. This scenario does not cover the full gamut of SQC. However, most problems encountered will occur within the above commands. To exit the software:

Highlight the bottom line of the main menu, press Enter

Exits the SQC software.

BATCH FILES

During a machine acceptance session, it is common to finish running Minitab and need to go directly to SQC. To aid in reducing the amount of keystrokes necessary to enter another directory, make a BATCH file. If the subdirectories have been created exactly as outlined in Getting Started, the following keystrokes will create a BATCH file that transfers control from Minitab to SQC.

[CD\]	Get into the root directory.
[CD\MINITAB]	Get into minitab directory.
[Edlin SQC.BAT]	Tells the computer to edit or create a file named SQC.BAT.
[1I]	Edlin command to insert new lines beginning at Line #1.
[Echo off]
[CLS]
[CD\SQC]
[SQC]
Press the F6 key and then Press Enter	Gets out of Edlin edit mode.
[1L]	Lists the file.
[E]	Gets out of Edlin and saves any changes to original file.

Now you have a BATCH file that transfers control from the Minitab directory to the SQC directory and invokes the SQC software. This file will save seven key strokes every time you go from Minitab to SQC. To use it, when in the Minitab directory, do the following:

[SQC]

Executes BATCH file.

The BATCH file will transfer control to the SQC directory and run the SQC software automatically.