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From the list ofsuitable pilot holes, the best piloting holes should be selectedbased on the following priority:(1) If only one hole is available, it must be considered in thefirst instance.(2) If there are a number of holes, then the location of theseholes should be examined. (a) If holes are located in the same direction as feed ofthe strip, then select one hole, which is nearest to thecentroid of the part.(b) If holes are located in the perpendicular direction asthat of feed, then select the two largest holes (whichare equal in diameter) and that are located at a dis-tance at least two times of sheet thickness.(3) Select the two largest holes (the diameters of which arewithin a pre-set percentage of each other), which satisfythe earlier conditions.Keeping in view of the above basic guidelines and recom-mendations, an expert system for automation of strip-layoutdesign for sheetmetalwork on progressive die has been devel-oped. A brief description of the proposed system is given asunder.3. Development and execution of theproposed systemKnowledge is acquired for each module of the proposedsystem from various sources (Kumar et al., 2006) includ-ing experienced die designers, shop floor engineers, diedesign handbooks, research journals, catalogues and indus-trial brochures. The design information gathered fromvarioussources has been converted into usable knowledge by fram-ing suitable production rules of the IF-THEN variety. For theproposed system, it was convenient to pide the whole set ofproduction rules comprising the knowledge base into sixmod-ules, namely OPRPLAN, OPRSEQ, PLTSEL, OPRSTAGE, SWLSELand STRPLYT. The production rules framed for each modulewere crosschecked from other team of die design experts bypresenting them IF-condition of the production rule of IF-THEN variety. A sample of production rules so framed andverified; and then incorporated in themodules of the proposedsystemis given in Table 1. The sequencing of production rulesof the proposed system is unstructured as this arrangementallows insertion of newproduction rules even by relatively lesstrained knowledge engineer. The rules are coded in AutoLISPlanguage as it can be interfaced with AutoCAD for model-ing of strip-layout. The production rules and the knowledgebase of the system are linked together by an inference mech-anism, which makes use of forward chaining. The knowledgebase of the proposed systemcomprisesmore than 300 produc-tion rules of IF-THEN variety. However, the system is flexibleenough as its knowledge base can be updated andmodified, ifnecessary, on the advancement in technology and availabilityof new facilities on shop floor.The execution of the systemis shown through a flow chartin Fig. 1. The system invites the user to model the blankusing AutoCAD commands. Next the user has to enter partdata information such as sheet thickness, sheet material, etc.through prompt area of AutoCAD. The system automaticallystores these part data in a part data file labeled as COMP.DAT.The firstmodule OPRPLANof the proposed systemdeterminesthe type of sheet metal operations required to manufacturethe part. The module invites the user to supply relevant inputdata namely dimensional tolerance and geometrical featuresof the part. The outputs of this module are in the form of rec-ommendations for the type of sheetmetal operations requiredtomanufacture the part. The nextmoduleOPRSEQdeterminesthe sequencing of recommended sheet metal operations. Ittakes its input directly fromthe output data file OPRPLAN.DATgenerated during the execution of module OPRPLAN. Themodule PLTSEL is developed for selection of proper pilotingscheme for positioning the strip accurately in each station ofprogressive die. The next module OPRSTAGE is developed forimparting expert advices for the number of stations requiredand preferred staging of operations on progressive die. Thismodule takes its inputs fromthe output data file OPRSEQ.DATgenerated during the execution of module OPRSEQ, and alsoinvites the user to enter job specific data as per the part fea-tures. Themodule SWLSEL determines the proper size of sheetmetal strip. The modeling module STRPLYT erases any previ-ous drawing existing in the drawing editor of AutoCAD andselects an appropriate screen setting for modeling the strip-layout. Next, it asks the user to select start point on the screenof AutoCAD. As soon as the user selects a start point using thecursor or entering in the prompt area of AutoCAD, themoduleSTRPLYTmodels the strip-layout automatically in the drawingeditor of AutoCAD.4. Validation of the proposed systemThe proposed system was tested for different types of sheetmetal parts for the problem of strip-layout design. Typicalprompts, user responses and the recommendations obtainedby the user during execution of the proposed system for oneexample component (Fig. 2) are given through Table 2. Thestrip-layout generated by the system is shown in Fig. 3. Theoutputs received from the system modules in form of iden-tification of operations, sequencing of operations, selectionof piloting scheme, number of stations required, staging ofoperations and size of stock strip are found similar and veryreasonable to those actually practiced by experienced diedesigners and process planners in stamping industry namelyIndo Asian Fuse Gear Limited,Murthal,