Method for part procurement in a production system with constrained resources

Claim 2

A computer implemented process for determining procurement level for parts (P) in a production system having constraints comprising at least one of constrained resources (r) and known maximum demands d j , comprising: 1) inputting to the computer, data including decision variables, production quantity, demand quantity, bill of material, bill of capacity and usage rate; 2) constructing in computer memory a production planning decision space consisting of independent sets of hyperplanes defined by decision variables q j ,t corresponding to production quantities for products (j), said constructing including the steps of: a) expressing a potential usage of part (p) as a linear combination of production quantities (q j ); b) limiting the production quantities (q j ) so that it is less than or equal to the maximum demand quantity (d j ); and c) limiting the production quantities (q j ) so that the usage of each other resource (r) based on multiple level bill of material and bill of capacity usage rates is less than or equal to the availability of that resource; 3) locating a region in the decision space corresponding to a high level of usage of part (p); and 4) interactively displaying to a user candidate values in said decision space corresponding to the highest level of usage of part (p) so assist the user in deciding quantities of part (p) to procure necessary to enable achievement of the highest level of service, corresponding to the highest level of usage of part (p), while maintaining the lowest possible WIP and inventory on the basis of linear demand, resource, and supply constraining information.

Claim 3

A method according to claim 1, wherein the decision space is temporally expanded by the step of separating each decision variable q j ,t into a set of decision variables q j ,t according to a calendar mechanism to determine the quantity of activity j to do in a period t, said step further including modifying the creation of said independent sets of hyperplanes by adding decision variables q j ,t corresponding to shipment of product, stock of materials, and scrapping of resources in each period; and expressing the demand for a product as demand quantities over time; and determining the time based cost factors on backlogging demand and carrying material; and expressing the availability of resources over time; and constructing an objective function consisting of a plurality of objective function coefficients and associated decision variables q( j ,t), wherein said objective function rewards the shipment of products using a specific part(p) and penalizes holding or scrapping of part (p) or products using part(p); and using said objective function to locate a region in the decision space corresponding to a high level of usage of part (p).

Claim 4

A method according to claim 2, wherein step 2) comprises: a) expressing a potential usage of part (p) in period t as a linear combination of production quantities q j ; b) limiting the production quantities q j so that a cumulative production through a period r is less than or equal to cumulative maximum demand quantity through period r; and c) limiting the production quantities q j so that the usage of each other material or capacity resource (r) in a time period r based on bill of material and bill of capacity usage rates is less than or equal to the availability of that resource in time period r; and wherein step (2) further comprises locating a region in the decision space corresponding to a high level of usage of part (p) in period r.

Claim 5

A method according to claim 2, comprising the additional step of procuring parts in a period closest to the actual usage period for said parts consistent with the constraints of known available external supply.

Claim 6

A method according to claim 1, wherein the decision space is temporally expanded by the steps of: (i) separating each decision variable q j ,t into a set of decision variables q j ,t according to a calendar mechanism to determine the quantity of activity i to do in a period t, said step further including modifying the creation of said independent sets of hyperplanes by adding decision variables q j ,t corresponding to shipment of product, stock of materials, and scrapping of resources in each period; and expressing the demand for a product as demand quantities over time; and determining the time based cost factors on backlogging demand and carrying material; and expressing the availability of resources over time; and constructing an objective function consisting of a plurality of objective function coefficients and associated decision variables q.sub.(j,t), wherein said objective function rewards the shipment of products using a specific part(p) and penalizes holding or scrapping of part (p) or products using part (p); and using said objective function to locate a region in the decision space corresponding to a high level of usage of part (p). (ii) adjusting the hyperplane to represent non-zero manufacturing lead times.

Claim 7

A method according to claim 5 where the Bill of Material BOM is multi-level ensuring that unnecessary parts are not procured when a choice exists between procuring parts or using existing subassemblies.

Claim 8

A method according to claim 1, wherein the step of locating an optimal region in the decision space comprising a high level of usage further includes constructing a special objective function comprising objective function coefficients for each of the decision variables.

Claim 9

A machine suitable for determining procurement level for parts (P) in a production arrangement having constraints comprising at least one of constrained resources (r i ) and known maximum demands (d j ) the machine comprising: 1) means for inputting data comprising variables including decision variables, production quantity, demand quantity, bill of material, bill of capacity and usage rates; 2) means for creating a production planned decision space comprising independent sets of hyperplanes defined by decision variables q j ,t corresponding to product quantities for product (j), said means for creating comprising a) expressing a potential usage of part p) in period t as a linear combination of production quantities (q(j)) b) limiting the production quantities q j so that a cumulative production through a period r is less than or equal to cumulative maximum demand quantity through period r; and c) limiting the production quantities q j so that the usage of each other resource (r) based on multiple level bill of material and bill of capacity usage rates is less than or equal to the availability of that resource and 3) means associated with each part (p) for locating a region in the decision space corresponding to the highest level of usage of part (p); and 4) means for interactively displaying to a user candidate values in said decision space corresponding to the highest level of usage of part (p) to assist the user in deciding quantities of part (p) to procure necessary to enable achievement of the highest level of service, corresponding to the highest level of usage of part (p), while maintaining the lowest possible Work in Process WIP and inventory on the basis of linear demand, resource, and supply constraining information.

Claim 10

A machine suitable for determining procurement level for parts (P) in a production arrangement having constraints comprising at least one of constrained resources (r i ) and known maximum demands (d j ) the machine comprising: 1) means for inputting data comprising variables including decision variables, production quantity, demand quantity, bill of material, bill of capacity and usage rates; 2) means for creating a production planned decision space comprising independent sets of hyperplanes defined by decision variables q j ,t corresponding to product quantities for product (j), said means for creating comprising a) expressing a potential usage of part p) in period t as a linear combination of production quantities (q(j)) b) limiting the production quantities q j so that a cumulative production through a period r is less than or equal to cumulative maximum demand quantity through period r; and c) limiting the production quantities q j so that the usage of each other resource (r) based on multiple level bill of material and bill of capacity usage rates is less than or equal to the availability of that resource and 3) means associated with each part (p) for locating a region in the decision space corresponding to the highest level of usage of part (p); and 4) means for interactively displaying to a user candidate values in said decision space corresponding to the highest level of usage of part (p) to assist the user in deciding quantities of part (p) to procure necessary to enable achievement of the highest level of service, corresponding to the highest level of usage of part (p), while maintaining the lowest possible Work in Process WIP and inventory on the basis of linear demand, resource, and supply constraining information.

Claim 11

A machine according to claim 8 wherein the bill of materials comprises multiple levels ensuring that unnecessary parts are not procured when a choice exists between procuring parts or using existing subassemblies.