- Email: [email protected]
Automating cost estimating systems
Computers ind. En~n9 Vol. 13, Nos I-4, pp.356-360, 1987 Printed in Great Britain. All rights reserved
0360-8352/87 $3.00+0.00 Copyright c 1987 Pergamon Journals Ltd
COST CONTROL AUTOMATING COST ESTIMATING SYSTEMS Sungyoul Lee Graduate Research Assistant Robert Perkins Engineering Computer Center North Dakota State University Fargo, North Dakota Dr. K. A. Ebeling Professor of Industrial Engineering and Management North Dakota State University Fargo, North Dakota
ABSTRACT Interest in Cost Estimating Systems (CES) has grown rapidly in the last few years. The availability, flexibility, speed, and accuracy of micro-computers have provided the impetus for automation of many indirect activities. Central to the successful automation of the cost estimating function is the relative ease with which the user can customize the application software to a unique set of materials, machines, and methods of the organization. Once customized to his particular applloation, cost estimating software must be easily adaptable to future business changes as well as changes in the cost estimating technology itself. This paper describes the development of a CES which provides e highly productive and flexible approach to user customization. The paper includes an explanation of the system's extensive data and program structure. It is capable of accommodating future technological changes resulting from the introduction of engineering work centers with CIM capabilities. The paper concludes with an illustration of its application to a highly diversified aerospace firm.
popular software packages evaluation, all of four systems provided reasonable estimates and were very competitive with each other. Goldberg found few differences in functional features. Even th6ugh a company has a good CES, there is a frequent need to customize the CES to the specific manufacturing environment of the company. Some of the common reasons for customlzstion are as follows : I.
Approaches to cost estimating vary widely. There is no one complete cost estimating system that will fit the unique environments of all companies. Therefore, any CES must be customized for the user's specific factory environments.
2.
In a batch manufacturing environment, customers expect products customized to their special needs. Because managers of batch manufacturing activities have typically encouraged special requests, the result is a wide range of product variations which 8 CES should be able to incorporate.
B.
To maintain historical cost data which insures that the CES estimates will be accurate and current, the CES makes estimates more and more accurate. Machine times, actual material costs, actual set up costs, and material usage variances all need to be fed back to the CES to update system data base. It is especially critics] in the cost estimating field.
4.
To adapt new manufacturing technologies in CES, the CES will need to be continually updated.
INTRODUCTION There is a strong trend in America toward fully automated factories which provide high productivity and a competitive edge. Underlying this trend is the development of a number of computer aided technologies. Traditionally, cost estimation has been a rather inexact science, where margins of inaccuracy of 25 percent and higher are common [12]. It relies more heavily on at, individual's experience and judgement than o~ a pool of scientific information. In other words, this kind of estimation is labor-intensive, error-prone and inconsistent. It is still being done manually in most American industries.
In order to satisfy above objectives, the CES must be flexible and adaptable to a wide range of customizing needs. Therefore this paper suggests an improved CES with a standardized program structure and unified data base external to the program source code. Moreover, the improved CES will provide s foundaticn for. the fully automated manufacturing company, by providing a good potential to bridge between a CAD/CAM system and Computer Aided Process Planning (CAPP) system. That is, linking CES with manufacturing. This paper does not attempt to extend the cost estimating equations oF the costing parameters which may vary for different shop floor' conditions.
Since consistency, accuracy, and speed are most inevitable factors in cost estimation, interest in the use of computers in Cost Estimating Systems (CES) has grown rapidly in the last few years. As a result, a number of commercial software packages have been developed. According to Goldberg's [3] four
356
Lee and Ebeling: Automating cost estimating systems
IMPROVED SYSTEM STRUCTURE
SPREADSHEET PREPARATION
The CES described herein was developed to provide a systematic and comprehensive a p p r o a c h t h a t facilitates c u s t o m i z a t i o n and m i n i m i z e s t h e number o f k e y s t r o k e s t h e u s e r n e e d s t o make i n o p e r a t i n g t h e s y s t e m .
The library of cost estimating programs employs any full screen editor such as PC-Write or Lotus. Using a full screen editor, the user has easy access to any position on the screen. It also allows the user to edit a multiple set of files.
Figure I provides an overview of the functional layout of the CES. As shown, the process begins with the part and assembly drawings and operation process charts of the product to be produced. A full screen editor is used to capture the parts llst and the work center production sequence as a data file. After the parts llst data file has been saved on a spreadsheet, the user executes a master control p r o g r a m . This program reads the parts list file and automatically loads and executes the appropriate raw material "cost estimating program if required. The material cost estimating program, when used, loads the material cost estimating parameter file and prompts the user for the inputs necessary to estimate the unit cost of the raw m~ter~al selected. User responses to the prompts and the cost calculations are then stored in the material result file. In similar fashion, the master control program calls each of the work center programs in the order specified by each of the part's production sequence. As the appropriate work center program is executed, the user is prompted for the appropriate inputs which are then stored in a separate work center result file. The material result file and work center result files are then used as input to produce a d e t a i l e d routing report, a tooling report, and a labor/machine summary report. Each of the reports is a file which can be examined or I ~ : l i f i e d individually through the use of the editor. These individual report files may also be used to produce hard copy print-out as needed. The individual report file structure allows the user of the system considerable flexlbillty to return to any point in the estimating process and change one or more of bls inputs or intermediate results without the need of going through the whole process again. It also provides a convenient means of modlfylng the cost estimating parameters and menus.
FIGURE
i.
CAI gl$ : I-4-X
Figure 2 shows an example of the spreadsheet which contains parts information such as a part number, material, operation sequence etc. Assuming a fixed format, the master control program reads the required data from the sheet. The same general method is used through out all the files which the user creates.
WORK CENTER PROGRAM STRUCTURE All of the work center programs are made with essentially the same program structure. It makes it easy for the user to follow one common structure rather than needing to learn a separate structure for each estimating program in the l~brary. Figure 3 illustrates the general flow of work center programs. Through each of the work center costing functions, the program will automatically load the common cost estimating project data associated with the particular work center (i.e., date, estimate for and by, lot size and total required). The user also has an opportunity to override any of the common parameters if he so chooses. Individual work center prompts vary with the type of work center. Responses to prompts are displayed on the screen and further modiflcat~ons can be made if desired. This feature provides the user with a chance to cross examine his responses more closely. It also protects the user from unnecessary and time consuming delays caused by ~ncorrectly entered inputs. Next the particular work center program performs the required calculations and displays the results on the screen. Again, the user has an opportunity to modify his responses. He can also perform sensitivity analysis with respect to the input parameters at this point.
COST ESTIMATING
MASTER CONTROL
357
PLOW PROCESS
358
Proceedings of the 9th Annual Conference on Computers & Industrial Engineering
DATA STRUCTURE The full screen editor is also used to create and edit the two common data bases, material data base and work center data base. Like reading of the Spreadsheet, the each work center program reads the required data from the data base, assuming a fixed format. The tabular structure of these data bases provides the user with easy access to customize the costing parameters without requiring complicated reprogramming techniques. With file descriptions in the data bases, the user can edit the data bases, if needed, by using full screen editor. A description of an example material and work center data base follows.
Material Data Base A separate table is used for each material type. Within this table is all the data needed for each generic type of work center. It provides parameter data sets for drilling, machining, turning, boring, and so on. Work Center Data Base Like the data structure for materials, there is a separate file for each generic work center. The first table in the file provides the user prompts for a specific machine selection. The prompts also identify the work center by cost center code. The first sub-table is followed by machine set up parameters and machine function parameters. As an example, Figure 4 shows a partial data base of bench assembly work center. A separate table is used for each key operation type. Each table consists of all the element times with whole descriptions of assembly options for that specific operation. RESULTS The improved CES supports four basic types of reports: i.e., work center detail, production labor/machine summary, tooling summary, and routing summary. All of the reports are accessible through any full screen editor and can therefore be modified at will. A description of each report follows.
Work Center Detail This report is produced as an automatic by-product of responding to the work center prompts and forms a basis for the remaining three summary reports. Figure 5 shows an example of this report. As shown in Figure 5, the work center detail report consists of the three parts, the cost estimating project data, an echo listing of user responses, and the costing results. Production Labor/Machlne Summary This summary report accumulates set up time by part number and the production run time for each part by work center. The summary program omits unused work center columns. Figure 6 shows an example of this report. Customizing the CES for individual work centers allows for collection of estimated machine hours for a specific machine
or group of machines. This modification then allows the user to accurately estimate required machine capacity for a given estimate. Tooling Summary This report provides an accumulation of all fixture design and fabrication expenses, It also includes the cost estimate of preparing the N/C part program by individual part number. Figure 7 shows an example of this report. Routing Summary The routing summary report provides a detailed manufacturing routing report for each part at the conclusion of the estimate. Figure 8 shows an example of this report. CONCLUSIONS Central to the successful automation of the cost estimating function is the relative ease with which the user can customize the application software to the user's unique complement of production equipment and materials. This paper has described basic techniques which improves the functionality of cost estimating software from a system maintenance and user point of view. Further work in customizing CES is being directed toward establishing a direct link of the CES with a CAD/CAM data base structure to automate the cost estimating function further.
REFERENCES I. "Cost Estimating Made Easier." Industry, June 1985. 2. IBM Co., BASIC by Microsoft, Version 1.1, 2nd ed., 1982. 3. Joel Goldberg, "Rating Cost-estimatlng Software." Manufacturing Engineering, February 1987. 4. John Timmersman,"Computer-Aided Technology Revolutionizes Field of Cost Estimating." Journal of Computerized Manufacturing. Commline, Vol. 15, No. 3, May-June 1986. 5. Machinability Data Center, Machining Data Handbook, Cincinnati, Ohio, 1972. 6. MiCAPP Inc., MiCAPP Computer Cost Estimating System Manual, 1985. 7. Philllp F. Ostwald, American Machinist Manufaoturin~ Cost Estimatin~ Guide, McGraw-Hill Book Co., 1983. 8. _ _ _ _ _ , Cost Estimating, 2nd ed.,Prentice-Hall,Inc., Englewood Cliffs, New Jersey, 1984. 9. _ _ _ _ _ , American Machinist Cost Estimator, McGraw-Hill, Inc., 1985. 10. R. D. Stewart and A. L. Stewart, Cost Estimatin$ wlth Microcomputer, McGraw-Hill Book Co., 1986. 11. Society of M~.ufacturing Engineers, Manufacturin~ Planning and Estimatin 5 Handbook, 1963. 12. "Turning Cost 'Guesstimating' Into Cost Estimating Capital Equipment Machining., Production Engineering, January 1986.
Lee and Ebeling: Automating cost estimating systems
FIGURE DATE : E S T I M A T E FOR: E S T I M A T E D BY: E S T I M A T E D OF: LOT SIZE : TOTAL REQ'D :
2.
SPREADSHEET
359
EXAMPLE
20/MARCH/87 ABC COMPANY LEE WHEEL 25 I00 ***
I-DRILL CONV 2-DRILL N/C 3-HONE 4-BROACH 5-LATHE CONV 6-LATHE N/C 7-MILL CONV
COST
CENTERS
8-BRIDGE PORT 9-HYDRO 1 0 - M A H O 600 I I - M A H O 50 12-CIM-X 13-OKUMA 14-CIN TURN ***
MATERIAL
*** 1 5 - V E E T HD 16-UNIV GRIND 17-JIG BORE 18-VMC 200 1 9 - V M C 150 20-PAINT/MARK 21-DEBURR
SELECTION
1...FREE EACH CARBON STEEL WR 2...CARBON STEEL WE 3...FREE EACH ALLOY STEEL WR 4...ALLOY STEEL WE 5...HIGH STRENGH STEEL WR 6...MARAGING STEEL WR 7...TOOL STEEL WR 8...NITRIDING STEEL WR 9...ARMOR PLATE WR 10...STRUCTURAL STEEL WR II...FREE EACH STAINLESS STEEL WR 12...STAINLESS STEEL WR 13...PRECIP HARDENING STAINLES S WR 14...CARBON STEEL CAST 15...ALLOY STEEL CAST
22-SHEET METAL 23-PROC 24-ELEC. ASSY 25-MECH ASSY 26-OTHER
*** 16. 17. 18. 19. 20. 21. 22 23 24 25. 26 27 28. 29. 30
.STAINLESS STEEL CAST .PRECIP HARDENING STAINLESS CAST .AUSTENITIC MANGANESE STEEL CAST .GRAY CAST IRON .DUCTILE CAST IRON .MALLEABLE CAST IRON ..ALUMINUM ALLOY WR ..ALUMINUM ALLOY CAST ..MAGNESIUM ALLOY WR .MAGNESIUM ALLOY CAST ..TITANIUM ALLOY WE ..COPPER ALLOY WE .COPPER ALLOY CAST .NICKEL ALLOY WR & CAST ..ZINC ALLOY CAST
PART PART MAT'L MAT'L MAT'L WORK CTR NUMBER LEVEL DESCRIPTION QTY/U EEL. SIZE COST ROUTING ........ +......... +.................... +....... +...... +.......... +..... ÷........... i04F440 1 ASSY PART I 2 3 12 1 1 / 1 6 N 2-18 203F450 1-1 ASSY PART 2 2 3/8 Y 25
FXOUR| 3. GENERAL PLON OF W0tK CENTRE PIOORAM$
~
FIGURE 4.
KEY OPERATION ELEMENTS 8ELECTION
GRT READ|E
I...HANDLE BASIC PART 2...TUMBLE OR TURN PARTD 3...pLACE AND POSITION PART 4...GET AND PLACE ADD*L PART (WITB RESPECT TO 3) 5...GETAND PLACE MULTIPLE PART 6...HANDLE TOOL 7...pASTENERE 8...pIXTURE EARDLIHGAMD C~UqPING 9...MISCELLANEOUS E L E N E N T 8
GET READE| I XBFODNATIOE FROM Y I | IITDOARD
0TABLE I@
DZBPLAY A EDIT n J i O | t ZIFOINATIOI
[ODT DSBB PIONFTD DEIST
] PROM TR| FILE ,
yes
GET DATA FROM TH| KEYBOARD
I
GET DATA FIRM TiE J MATDRXAL • MACDXD|~ DATA FXLIO J
l
DISPLAY J EDIT DATA J
J
DO OALCOLAYIODB
J
DIDFLAZ REOELYD
l
J
HANDLE BASIC PART
TYPE OP HANDLING PART SIZE TOES PLACE STACI COI~TOR ................... +......... +......... ÷......... ÷......... + V E R Y SMALL .|27 ,|3% .|42 ,IRE SMALL .|21 .R36 .|39 ,|OR MEDIUM .%3e .|42 .|45 ,|42 LARGE .878 ,|84 .a%J oR54 VERY LARGE .||O .13 .14 .|JR ...................
+
BENCH ASSEMBLY WORK CENTER DATA EdgE| EXJULPL|
RS-11\9@
+ .........
+ .........
÷ .........
+ .........
÷
360
Proceedings of the 9th Annual Conference on Computers & Industrial Engineering
FIGURE
5.
WORK
CENTER
DETAIL
EXAMPLE
### BENCH ASSEMBLY ESTIMATE ### DATE : 20~MARCH/87 PART NUMBER : 203F450 ESTIMATE FOR: ABC COMPANY PART DESCRIPTION : ASSY PART ESTIMATED BY: L E E NEXT HIGHIER PART: ASSY PART ESTIMATED OF: WHEEL QUANTITY / UNIT : 2 LOT SIZE : 25 TOTAL REQ'D : 100 ##### USER PROMPTS ############################################# NO OF ASSEMBLY TOOLS : 1 1 .power driver TOTAL NO OF OPERATIONS : 2 THE OPERATION NUMBER : NO OF ELEMENTS FOR OPER. NO 1 : KEY ELEMENT SELECTION : 1 ..HANDLE ELEMENT NO : TYPE OF OPTIONS: NO OF COMPONENTS : KEY ELEMENT SELECTION : 2 ..TUMBLE ELEMENT NO : TYPE OF OPTIONS : NO OF COMPONENTS : NEXT OPFA%ATION OPTION :
2 1
1 2 BASIC PART 1 2 ..PLACE 3 OR TURN PARTS 2 2 ..90 - 180 3 2
THE OPERATION NUMBER : 2 NO OF EL~24ENTS FOR OPER. NO 2 : i KEY ELEMENT SELECTION : 9 ..MISCELLANEOUS ELEMENTS ELEMENT NO : i TYPE OF OPTIONS : 7 ..AIR CLEAN(LARGE) NO OF COMPONENTS : 7 NEXT OPERATION OPTION : 3 NO OF PARTS PER EACH CYCLE : 1 PF & D : .18 SHOP RATE : 24 TOOL CODE : MF TOOL DESIGN TIME : 20 TOOL FAB. TIME : 24 MATERIAL COST FOR FIXTURE : 20 NC PROGRAMMING TIME : 10 #### RESULTS ################################################### TOTAL OPERATION TIME : 0.96 T O T A L T I M E P E R PC. : 0.96 TOTAL OPERATION T I M E W I T H PF & D : 1.13 TOTAL COST (S) : 0.45 TOTAL PARTS PER HOUR AT STANDARD : 62.70 TOTAL PARTS PER HOUR AT ACTUAL : 53.13
FIGURE
6.
PRODUCTION
LABOR/MACHINE
SUMMARY
EXAMPLE
PART NO .........
DESCRIPTION ÷ ...............
WORK CENTERS M E C H AS&"/ VMC 200 DRILL N/C QTY SET-UP RUN 25 18 2 + .... + ....... + ....... ÷ .......... + ......... + ......... +
104F452 203F450 .........
ASSY PART 1 ASSY PART 2 + ...............
2 94 3.64 2 0 2.64 2.64 + .... + ....... + ....... + .......... 94
FIGURE PART NO ......... I03F440 204F450 305F458
; ~
7.
DESCRIPTION ÷ ................. ASSY ASSY ASSY
PART PART PART
1 2 3
TOOLING
6.28
SUMMARY
TOOL CODE + ...........
2.64
1.33 + .........
2.31
M A T . $$ N/C + ........ + ....... ÷
30
40
50
10
20
30
60 50 40
-÷ .................................. ~; ...... ~; ..... ~ - ~ ; ..... [;;
FIGURE
8.
ROUTING
SUM~Y
+
1.33
EXAMPLE
T/D T/F + ........ ÷ ........
DJ MCX MF
2.31 + .........
÷
EXAMPLE
................................................................................. CONTROL NO. :200 PART NAME PART NO. :504F452 N.H.A. NO ESTIMATED QTY.: 2 ..... ÷ ......... + ...................................... OP
q;
#
MACN.
CTR.
OPER.
DESCRIPTION
: : 123
AS&"/
÷ ......... TOOL
CODE
PART
5
÷ ....... ÷ ........ SET
UP
RUN
÷ .... ~;~ ................................................... ÷--~; ..... [ ~ ; ;
DRILLING DJ ................................................................................. 20 870 57 BORING MCX .................................................................................
2.31
0360-8352/87 $3.00+0.00 Copyright c 1987 Pergamon Journals Ltd
COST CONTROL AUTOMATING COST ESTIMATING SYSTEMS Sungyoul Lee Graduate Research Assistant Robert Perkins Engineering Computer Center North Dakota State University Fargo, North Dakota Dr. K. A. Ebeling Professor of Industrial Engineering and Management North Dakota State University Fargo, North Dakota
ABSTRACT Interest in Cost Estimating Systems (CES) has grown rapidly in the last few years. The availability, flexibility, speed, and accuracy of micro-computers have provided the impetus for automation of many indirect activities. Central to the successful automation of the cost estimating function is the relative ease with which the user can customize the application software to a unique set of materials, machines, and methods of the organization. Once customized to his particular applloation, cost estimating software must be easily adaptable to future business changes as well as changes in the cost estimating technology itself. This paper describes the development of a CES which provides e highly productive and flexible approach to user customization. The paper includes an explanation of the system's extensive data and program structure. It is capable of accommodating future technological changes resulting from the introduction of engineering work centers with CIM capabilities. The paper concludes with an illustration of its application to a highly diversified aerospace firm.
popular software packages evaluation, all of four systems provided reasonable estimates and were very competitive with each other. Goldberg found few differences in functional features. Even th6ugh a company has a good CES, there is a frequent need to customize the CES to the specific manufacturing environment of the company. Some of the common reasons for customlzstion are as follows : I.
Approaches to cost estimating vary widely. There is no one complete cost estimating system that will fit the unique environments of all companies. Therefore, any CES must be customized for the user's specific factory environments.
2.
In a batch manufacturing environment, customers expect products customized to their special needs. Because managers of batch manufacturing activities have typically encouraged special requests, the result is a wide range of product variations which 8 CES should be able to incorporate.
B.
To maintain historical cost data which insures that the CES estimates will be accurate and current, the CES makes estimates more and more accurate. Machine times, actual material costs, actual set up costs, and material usage variances all need to be fed back to the CES to update system data base. It is especially critics] in the cost estimating field.
4.
To adapt new manufacturing technologies in CES, the CES will need to be continually updated.
INTRODUCTION There is a strong trend in America toward fully automated factories which provide high productivity and a competitive edge. Underlying this trend is the development of a number of computer aided technologies. Traditionally, cost estimation has been a rather inexact science, where margins of inaccuracy of 25 percent and higher are common [12]. It relies more heavily on at, individual's experience and judgement than o~ a pool of scientific information. In other words, this kind of estimation is labor-intensive, error-prone and inconsistent. It is still being done manually in most American industries.
In order to satisfy above objectives, the CES must be flexible and adaptable to a wide range of customizing needs. Therefore this paper suggests an improved CES with a standardized program structure and unified data base external to the program source code. Moreover, the improved CES will provide s foundaticn for. the fully automated manufacturing company, by providing a good potential to bridge between a CAD/CAM system and Computer Aided Process Planning (CAPP) system. That is, linking CES with manufacturing. This paper does not attempt to extend the cost estimating equations oF the costing parameters which may vary for different shop floor' conditions.
Since consistency, accuracy, and speed are most inevitable factors in cost estimation, interest in the use of computers in Cost Estimating Systems (CES) has grown rapidly in the last few years. As a result, a number of commercial software packages have been developed. According to Goldberg's [3] four
356
Lee and Ebeling: Automating cost estimating systems
IMPROVED SYSTEM STRUCTURE
SPREADSHEET PREPARATION
The CES described herein was developed to provide a systematic and comprehensive a p p r o a c h t h a t facilitates c u s t o m i z a t i o n and m i n i m i z e s t h e number o f k e y s t r o k e s t h e u s e r n e e d s t o make i n o p e r a t i n g t h e s y s t e m .
The library of cost estimating programs employs any full screen editor such as PC-Write or Lotus. Using a full screen editor, the user has easy access to any position on the screen. It also allows the user to edit a multiple set of files.
Figure I provides an overview of the functional layout of the CES. As shown, the process begins with the part and assembly drawings and operation process charts of the product to be produced. A full screen editor is used to capture the parts llst and the work center production sequence as a data file. After the parts llst data file has been saved on a spreadsheet, the user executes a master control p r o g r a m . This program reads the parts list file and automatically loads and executes the appropriate raw material "cost estimating program if required. The material cost estimating program, when used, loads the material cost estimating parameter file and prompts the user for the inputs necessary to estimate the unit cost of the raw m~ter~al selected. User responses to the prompts and the cost calculations are then stored in the material result file. In similar fashion, the master control program calls each of the work center programs in the order specified by each of the part's production sequence. As the appropriate work center program is executed, the user is prompted for the appropriate inputs which are then stored in a separate work center result file. The material result file and work center result files are then used as input to produce a d e t a i l e d routing report, a tooling report, and a labor/machine summary report. Each of the reports is a file which can be examined or I ~ : l i f i e d individually through the use of the editor. These individual report files may also be used to produce hard copy print-out as needed. The individual report file structure allows the user of the system considerable flexlbillty to return to any point in the estimating process and change one or more of bls inputs or intermediate results without the need of going through the whole process again. It also provides a convenient means of modlfylng the cost estimating parameters and menus.
FIGURE
i.
CAI gl$ : I-4-X
Figure 2 shows an example of the spreadsheet which contains parts information such as a part number, material, operation sequence etc. Assuming a fixed format, the master control program reads the required data from the sheet. The same general method is used through out all the files which the user creates.
WORK CENTER PROGRAM STRUCTURE All of the work center programs are made with essentially the same program structure. It makes it easy for the user to follow one common structure rather than needing to learn a separate structure for each estimating program in the l~brary. Figure 3 illustrates the general flow of work center programs. Through each of the work center costing functions, the program will automatically load the common cost estimating project data associated with the particular work center (i.e., date, estimate for and by, lot size and total required). The user also has an opportunity to override any of the common parameters if he so chooses. Individual work center prompts vary with the type of work center. Responses to prompts are displayed on the screen and further modiflcat~ons can be made if desired. This feature provides the user with a chance to cross examine his responses more closely. It also protects the user from unnecessary and time consuming delays caused by ~ncorrectly entered inputs. Next the particular work center program performs the required calculations and displays the results on the screen. Again, the user has an opportunity to modify his responses. He can also perform sensitivity analysis with respect to the input parameters at this point.
COST ESTIMATING
MASTER CONTROL
357
PLOW PROCESS
358
Proceedings of the 9th Annual Conference on Computers & Industrial Engineering
DATA STRUCTURE The full screen editor is also used to create and edit the two common data bases, material data base and work center data base. Like reading of the Spreadsheet, the each work center program reads the required data from the data base, assuming a fixed format. The tabular structure of these data bases provides the user with easy access to customize the costing parameters without requiring complicated reprogramming techniques. With file descriptions in the data bases, the user can edit the data bases, if needed, by using full screen editor. A description of an example material and work center data base follows.
Material Data Base A separate table is used for each material type. Within this table is all the data needed for each generic type of work center. It provides parameter data sets for drilling, machining, turning, boring, and so on. Work Center Data Base Like the data structure for materials, there is a separate file for each generic work center. The first table in the file provides the user prompts for a specific machine selection. The prompts also identify the work center by cost center code. The first sub-table is followed by machine set up parameters and machine function parameters. As an example, Figure 4 shows a partial data base of bench assembly work center. A separate table is used for each key operation type. Each table consists of all the element times with whole descriptions of assembly options for that specific operation. RESULTS The improved CES supports four basic types of reports: i.e., work center detail, production labor/machine summary, tooling summary, and routing summary. All of the reports are accessible through any full screen editor and can therefore be modified at will. A description of each report follows.
Work Center Detail This report is produced as an automatic by-product of responding to the work center prompts and forms a basis for the remaining three summary reports. Figure 5 shows an example of this report. As shown in Figure 5, the work center detail report consists of the three parts, the cost estimating project data, an echo listing of user responses, and the costing results. Production Labor/Machlne Summary This summary report accumulates set up time by part number and the production run time for each part by work center. The summary program omits unused work center columns. Figure 6 shows an example of this report. Customizing the CES for individual work centers allows for collection of estimated machine hours for a specific machine
or group of machines. This modification then allows the user to accurately estimate required machine capacity for a given estimate. Tooling Summary This report provides an accumulation of all fixture design and fabrication expenses, It also includes the cost estimate of preparing the N/C part program by individual part number. Figure 7 shows an example of this report. Routing Summary The routing summary report provides a detailed manufacturing routing report for each part at the conclusion of the estimate. Figure 8 shows an example of this report. CONCLUSIONS Central to the successful automation of the cost estimating function is the relative ease with which the user can customize the application software to the user's unique complement of production equipment and materials. This paper has described basic techniques which improves the functionality of cost estimating software from a system maintenance and user point of view. Further work in customizing CES is being directed toward establishing a direct link of the CES with a CAD/CAM data base structure to automate the cost estimating function further.
REFERENCES I. "Cost Estimating Made Easier." Industry, June 1985. 2. IBM Co., BASIC by Microsoft, Version 1.1, 2nd ed., 1982. 3. Joel Goldberg, "Rating Cost-estimatlng Software." Manufacturing Engineering, February 1987. 4. John Timmersman,"Computer-Aided Technology Revolutionizes Field of Cost Estimating." Journal of Computerized Manufacturing. Commline, Vol. 15, No. 3, May-June 1986. 5. Machinability Data Center, Machining Data Handbook, Cincinnati, Ohio, 1972. 6. MiCAPP Inc., MiCAPP Computer Cost Estimating System Manual, 1985. 7. Philllp F. Ostwald, American Machinist Manufaoturin~ Cost Estimatin~ Guide, McGraw-Hill Book Co., 1983. 8. _ _ _ _ _ , Cost Estimating, 2nd ed.,Prentice-Hall,Inc., Englewood Cliffs, New Jersey, 1984. 9. _ _ _ _ _ , American Machinist Cost Estimator, McGraw-Hill, Inc., 1985. 10. R. D. Stewart and A. L. Stewart, Cost Estimatin$ wlth Microcomputer, McGraw-Hill Book Co., 1986. 11. Society of M~.ufacturing Engineers, Manufacturin~ Planning and Estimatin 5 Handbook, 1963. 12. "Turning Cost 'Guesstimating' Into Cost Estimating Capital Equipment Machining., Production Engineering, January 1986.
Lee and Ebeling: Automating cost estimating systems
FIGURE DATE : E S T I M A T E FOR: E S T I M A T E D BY: E S T I M A T E D OF: LOT SIZE : TOTAL REQ'D :
2.
SPREADSHEET
359
EXAMPLE
20/MARCH/87 ABC COMPANY LEE WHEEL 25 I00 ***
I-DRILL CONV 2-DRILL N/C 3-HONE 4-BROACH 5-LATHE CONV 6-LATHE N/C 7-MILL CONV
COST
CENTERS
8-BRIDGE PORT 9-HYDRO 1 0 - M A H O 600 I I - M A H O 50 12-CIM-X 13-OKUMA 14-CIN TURN ***
MATERIAL
*** 1 5 - V E E T HD 16-UNIV GRIND 17-JIG BORE 18-VMC 200 1 9 - V M C 150 20-PAINT/MARK 21-DEBURR
SELECTION
1...FREE EACH CARBON STEEL WR 2...CARBON STEEL WE 3...FREE EACH ALLOY STEEL WR 4...ALLOY STEEL WE 5...HIGH STRENGH STEEL WR 6...MARAGING STEEL WR 7...TOOL STEEL WR 8...NITRIDING STEEL WR 9...ARMOR PLATE WR 10...STRUCTURAL STEEL WR II...FREE EACH STAINLESS STEEL WR 12...STAINLESS STEEL WR 13...PRECIP HARDENING STAINLES S WR 14...CARBON STEEL CAST 15...ALLOY STEEL CAST
22-SHEET METAL 23-PROC 24-ELEC. ASSY 25-MECH ASSY 26-OTHER
*** 16. 17. 18. 19. 20. 21. 22 23 24 25. 26 27 28. 29. 30
.STAINLESS STEEL CAST .PRECIP HARDENING STAINLESS CAST .AUSTENITIC MANGANESE STEEL CAST .GRAY CAST IRON .DUCTILE CAST IRON .MALLEABLE CAST IRON ..ALUMINUM ALLOY WR ..ALUMINUM ALLOY CAST ..MAGNESIUM ALLOY WR .MAGNESIUM ALLOY CAST ..TITANIUM ALLOY WE ..COPPER ALLOY WE .COPPER ALLOY CAST .NICKEL ALLOY WR & CAST ..ZINC ALLOY CAST
PART PART MAT'L MAT'L MAT'L WORK CTR NUMBER LEVEL DESCRIPTION QTY/U EEL. SIZE COST ROUTING ........ +......... +.................... +....... +...... +.......... +..... ÷........... i04F440 1 ASSY PART I 2 3 12 1 1 / 1 6 N 2-18 203F450 1-1 ASSY PART 2 2 3/8 Y 25
FXOUR| 3. GENERAL PLON OF W0tK CENTRE PIOORAM$
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FIGURE 4.
KEY OPERATION ELEMENTS 8ELECTION
GRT READ|E
I...HANDLE BASIC PART 2...TUMBLE OR TURN PARTD 3...pLACE AND POSITION PART 4...GET AND PLACE ADD*L PART (WITB RESPECT TO 3) 5...GETAND PLACE MULTIPLE PART 6...HANDLE TOOL 7...pASTENERE 8...pIXTURE EARDLIHGAMD C~UqPING 9...MISCELLANEOUS E L E N E N T 8
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TYPE OP HANDLING PART SIZE TOES PLACE STACI COI~TOR ................... +......... +......... ÷......... ÷......... + V E R Y SMALL .|27 ,|3% .|42 ,IRE SMALL .|21 .R36 .|39 ,|OR MEDIUM .%3e .|42 .|45 ,|42 LARGE .878 ,|84 .a%J oR54 VERY LARGE .||O .13 .14 .|JR ...................
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BENCH ASSEMBLY WORK CENTER DATA EdgE| EXJULPL|
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360
Proceedings of the 9th Annual Conference on Computers & Industrial Engineering
FIGURE
5.
WORK
CENTER
DETAIL
EXAMPLE
### BENCH ASSEMBLY ESTIMATE ### DATE : 20~MARCH/87 PART NUMBER : 203F450 ESTIMATE FOR: ABC COMPANY PART DESCRIPTION : ASSY PART ESTIMATED BY: L E E NEXT HIGHIER PART: ASSY PART ESTIMATED OF: WHEEL QUANTITY / UNIT : 2 LOT SIZE : 25 TOTAL REQ'D : 100 ##### USER PROMPTS ############################################# NO OF ASSEMBLY TOOLS : 1 1 .power driver TOTAL NO OF OPERATIONS : 2 THE OPERATION NUMBER : NO OF ELEMENTS FOR OPER. NO 1 : KEY ELEMENT SELECTION : 1 ..HANDLE ELEMENT NO : TYPE OF OPTIONS: NO OF COMPONENTS : KEY ELEMENT SELECTION : 2 ..TUMBLE ELEMENT NO : TYPE OF OPTIONS : NO OF COMPONENTS : NEXT OPFA%ATION OPTION :
2 1
1 2 BASIC PART 1 2 ..PLACE 3 OR TURN PARTS 2 2 ..90 - 180 3 2
THE OPERATION NUMBER : 2 NO OF EL~24ENTS FOR OPER. NO 2 : i KEY ELEMENT SELECTION : 9 ..MISCELLANEOUS ELEMENTS ELEMENT NO : i TYPE OF OPTIONS : 7 ..AIR CLEAN(LARGE) NO OF COMPONENTS : 7 NEXT OPERATION OPTION : 3 NO OF PARTS PER EACH CYCLE : 1 PF & D : .18 SHOP RATE : 24 TOOL CODE : MF TOOL DESIGN TIME : 20 TOOL FAB. TIME : 24 MATERIAL COST FOR FIXTURE : 20 NC PROGRAMMING TIME : 10 #### RESULTS ################################################### TOTAL OPERATION TIME : 0.96 T O T A L T I M E P E R PC. : 0.96 TOTAL OPERATION T I M E W I T H PF & D : 1.13 TOTAL COST (S) : 0.45 TOTAL PARTS PER HOUR AT STANDARD : 62.70 TOTAL PARTS PER HOUR AT ACTUAL : 53.13
FIGURE
6.
PRODUCTION
LABOR/MACHINE
SUMMARY
EXAMPLE
PART NO .........
DESCRIPTION ÷ ...............
WORK CENTERS M E C H AS&"/ VMC 200 DRILL N/C QTY SET-UP RUN 25 18 2 + .... + ....... + ....... ÷ .......... + ......... + ......... +
104F452 203F450 .........
ASSY PART 1 ASSY PART 2 + ...............
2 94 3.64 2 0 2.64 2.64 + .... + ....... + ....... + .......... 94
FIGURE PART NO ......... I03F440 204F450 305F458
; ~
7.
DESCRIPTION ÷ ................. ASSY ASSY ASSY
PART PART PART
1 2 3
TOOLING
6.28
SUMMARY
TOOL CODE + ...........
2.64
1.33 + .........
2.31
M A T . $$ N/C + ........ + ....... ÷
30
40
50
10
20
30
60 50 40
-÷ .................................. ~; ...... ~; ..... ~ - ~ ; ..... [;;
FIGURE
8.
ROUTING
SUM~Y
+
1.33
EXAMPLE
T/D T/F + ........ ÷ ........
DJ MCX MF
2.31 + .........
÷
EXAMPLE
................................................................................. CONTROL NO. :200 PART NAME PART NO. :504F452 N.H.A. NO ESTIMATED QTY.: 2 ..... ÷ ......... + ...................................... OP
q;
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MACN.
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OPER.
DESCRIPTION
: : 123
AS&"/
÷ ......... TOOL
CODE
PART
5
÷ ....... ÷ ........ SET
UP
RUN
÷ .... ~;~ ................................................... ÷--~; ..... [ ~ ; ;
DRILLING DJ ................................................................................. 20 870 57 BORING MCX .................................................................................
2.31