System and Method for Determining Quality Analysis on Fabrication and/or Assembly Design Using Shop Capability Data

This invention relates to quality determination analysis and more particularly to quality determination analysis on fabrication and/or assembly designs.

It is highly desirable in today's market place to provide higher quality products at lower cost by improving the quality of the fabrication and assembly designs. One such quality measurement has been termed the "six sigma" model for quality. Some view this six sigma measurement in terms of the total number of failures for a given overall fabrication or assembly design and others include every fabrication and assembly feature of that design.

It is highly desirable to provide, during the fabrication or assembly design process, a convenient way of analyzing the results of that design in terms of quality and the results of alternative fabrication or assembly procedures. This will permit the designer to choose those procedures for a given fabrication or assembly design feature that produce the best quality.

In accordance with one embodiment of the present invention, quality analysis on fabrication and/or assembly designs is achieved using the shop capability data stored in a database.

In the drawing:

FIG. 1 is a block diagram of the system in accordance with one embodiment of the present invention.

FIG. 2 illustrates the arrangement of a process capability data file in the system of FIG. 1.

FIGS. 3, 3a, 3b and 3c are flow charts of the application program according to one embodiment of the present invention.

FIG. 4 is a screen view of the main menu.

FIG. 5 is a screen view of a listing of assembly work sheets.

FIG. 5a is an example of a menu of fabrication worksheets.

FIG. 6 is a screen view of an assembly worksheet menu.

FIG. 6a is a screen view of the assembly worksheet menu with an example.

FIG. 7 is a flow chart of the analyzer subroutine of FIG. 3a and 3b.

Referring to FIG. 1, there is illustrated the file server 11 which includes therewith user interface layer 13 and application program 15 in addition to the process capability data file 17. A designer at terminal 21 for example, may interface at layer 13 the file server 11 and the application program 15 via LAN network 23. The user at terminal 21 (DOS) or terminal 25 (UNIX) in accordance with the system described may also interface to a design center 24 for user consulting. The process capability data file 17 in server 11 may be improved or altered by the process owners at terminal 27 also coupled to the file server 11 via a coupling means 28. Updating of the process capability data file by programming at system 30 may be also input to the process capability data file 17 of the file server 11 over coupling means 31 as shown in FIG. 1 to update the files, in particular the process capability data file. The file 17 may be a magnetic storage device such as a magnetic disc or tape or a semiconductor storage device such as a ROM, a CD ROM or a RAM.

FIG. 2 illustrates how the manufacturing process capability data file 17 may be arranged. For example, the process capability file 17 may be comprised of files for mechanical assembly, optics assembly, printed wiring board (PWB) assembly, SMT assembly, detector assembly, microwave assembly, symbolizing, deburring, coating, microwave fabrication, detector fabrication, SMT fabrication, PWB fabrication, optics fabrication, metal fabrication, non-metal fabrication and composites. Each of these files may further have more definition therein such as in the example of metal fabrication may have sub-databases of casting, forming, sheet metal, milling, and turning. The process of turning may further have the sub-database of rough turn, semi finish turn, finish turn, grind and hone. These databases would be updated, corrected, and maintained via the file development updates maintenance by programming as indicated by block 30 of FIG. 1. The names and addresses of process owners will be maintained and provided from block 27.

FIGS. 3, 3a, 3b and 3c shows a functional flow chart for the application program 15 in the file server 11 accessed by a user at terminal 21.. File server 11 includes a CPU 11a which runs the application program 15 and accesses the process capability files 17 in accordance with normal computer processing. Referring to FIG. 3, the first Step 301 is to access the file server 11 over the LAN 23. The second Step 302 is to select the process capability data file 17 in the file server 11 and the application 15. The application 15 will present to the user at terminal 21 the question in Step 303 whether to view the database or to call up a worksheet for fabrication, a worksheet for assembly, or select the stand alone DPU analysis. A typical screen is shown in FIG. 4 At this point, selection of either the Fab Worksheet or Assembly Worksheet will invoke identical worksheet formats and analysis functions with the only differences being in the worksheet headings which indicate either a Fab (fabrication) worksheet (Step 304) or Assembly worksheet (Step 324). If the worksheet for assembly is selected in Step 324, a technology must then be selected from the list of technologies mentioned previously. That selection would take place in Step 325 and follows diagram of FIG. 3b. An example of a menu of assembly worksheets is shown in FIG. 5 and an example of a menu of fabrication worksheets is shown in FIG. 5a. Interconnect, for example, is selected in the menu of FIG. 5. For a given technology, a worksheet form on the CPU screen is provided from the process capability data file 17 in Step 326. Assume, for example, a Mechanical Assembly worksheet is selected in Step 326. In Step 326 a standard worksheet format will be displayed with the title in the worksheet heading indicating, for example, "Mechanical Assembly Process Worksheet." FIG. 6 is a blank mechanical assembly worksheet and FIG. 6a is an example of a filled in mechanical assembly process worksheet. A similar worksheet would be called up for a selected fabrication worksheet such as metal. The user after calling up the worksheet can place a cursor on a button or area and "enter" or a selection arrow using a mouse and click on the button on area to edit, browse, file, print, verify, analyze, pareto, consult, get help, etc. A file is retrieved via steps 310 or 330 which can be edited via steps 331,331a or 311 and 311a. The worksheet is analyzed in Steps 307 and 327. The analyzed step 307,327 follows the flow chart of FIG. 7. In the first step 701 of FIG. 7, the design engineer is presented a screen that notifies that he is in a particular technology and given a listing of selectable processes and subprocesses in that technology from process capability data file 17. The design engineer once he has selected the process and subprocess is also notified of is given a listing of parameters. When sufficient parameters are provided, the system as indicated in Step 702 pulls out from the data file 17 the process mean standard deviation or DPMO, opportunity count, distribution code, short/long term indicator, actual or estimate capability for the process under analysis. From that information, if the DPMO is presented the DPU is calculated in Step 703 and if standard deviation DPU is calculated by Step 704 to present that data on a screen shown in 705. This screen summarizes a description trail and calculated information along with pertinent process information. This data is then put on the appropriate row and column of the associated process. Once this is done for all rows, all processes are then totalled for the total opportunity and total DPU. If a consultant is requested, a message is sent via Step 309 or 329. A pareto listing of the file is made in steps 312, 313, 332 and 333. The worksheet format is divided vertically into seven sections indicated at the left in FIG. 6:

The worksheet column titles found in section 5 of the worksheet format discussed above, along with a description of each column follow:

The input procedure for the "Analysis Field" in Section 6, described above, follows:

1. After entering the required information in the "Heading" section of the worksheet, the user will list the Fabrication and/or Assembly processes required to manufacture the unit being analyzed (preferably in the proper sequential order). The "technology code" for each process is automatically displayed in their respective data fields in the TECH CODE column.

2. The user enters the number of applications of each process in their respective fields in the QTY column.

3. The user will "highlight" the process description on line number I and either enter the process code (if known) or select the ANALYZE function button.

4. The user follows the instructions for using the functions while in the ANALYZE mode to supply detailed descriptions of all processes listed in the "Process Description" column beginning with line number 1 for automatic retrieval of process capability data from the Process Capability Data File 17. As the process capability data is retrieved for the process, the process capability data is automatically entered into it's respective data field in the worksheet (whether a DPMO or a STD DEV); the process code is automatically entered for the process in it's respective data field in the PROCESS CODE column; the process opportunity count for the process is automatically retrieved from the Process Capability Data File 17 and entered into it's respective data field in the PROCESS OPPOR column; the total number of opportunities associated with the process is automatically calculated and entered in it's respective data field in the TOTAL OPPOR column; the DPU for the process is automatically calculated and entered in it's respective data field in the DPU column; an "A" (ACTUAL) or "E" (ESTIMATE) is automatically retrieved from the Process Capability Data File 17 and entered in it's respective data field in the A/E column; and the PCL PROCESS DESCRIPTION is automatically retrieved form the Process Capability Data File 17 and entered into it's respective data field in the PCL PROCESS DESCRIPTION column. The flow chart for steps taken while in ANALYZE mode is shown in FIG. 7.

5. Steps 2 & 3 are repeated until all processes listed have data in their respective DPMO or STD DEV columns.

If the VIEW DATABASE function is selected at Step 303, Step 316 would allow the user to select a particular technology area (Step 316a) of the Process Capability Data File 17 for viewing or to select the entire Capability Data File 17 in all technology areas in Step 316b for viewing.

If the STANDALONE DPU ANALYSIS function is selected at Step 303, Step 317 would allow the user to perform a DPU analysis on a single process by selecting the appropriate technology area in Step 318, entering the detailed process description through selection of process descriptors from the Process Capability Data File 17 and entering the number of applications for the process in Step 319. Completion of data entry invokes a window with the calculated total opportunity count and calculated DPU for the process in step 320. If the requested data is not found in the Process Capability Data File 17, the user may choose to select the CONSULT button function to invoke the input screen for Process Consulting help. Selecting the CONSULT button (Step 321) will invoke a screen with instructions and function buttons for sending a message to an appropriate consultant (Step 322) requesting the desired process capability data.

In accordance with the system as described above, a design engineer is allowed to predict the number of types of defects that are expected to occur during production of the product(s) analyzed using this system. This system uses established statistical mathematical concepts and measured manufacturing process capability data stored in a Process Capability Data File 17 to perform DPU predictions for each manufacturing process used. The design engineer is also allowed to use the embedded Pareto analysis functions to facilitate evaluation of alternative designs before actual manufacturing occurs.