WORK IN PROCESS INVENTORY ANALYSIS TOOL

• US 20110238537A1
• Filed: 03/23/2010
• Published: 09/29/2011
• Est. Priority Date: 03/23/2010
• Status: Abandoned Application

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations Incorporated (General Motors Company)
• Inventors: Wilson, Laird M., Kincer, Edwin R., Harris, Douglas J., Gonzales, Eric A.
• Application Number:
  US12/729,551
• Publication Number:
  US 20110238537A1
• Time in Patent Office: Days
• US Class Current: 705/29
• CPC Class Codes: G06Q 10/067 Enterprise or organisation modelling
• CPC Class Codes: G06Q 10/087 Inventory or stock management, e.g. order filling, procurement or balancing against orders
• CPC Class Codes: G06Q 10/0875 Itemisation or classification of parts, supplies or services, e.g. bill of materials

Abstract

A method of managing work-in-process (WIP) inventory includes receiving inputs, via a user interface of a computer processing device. The inputs correspond to variables defined for modules. Each of the modules includes a set of instructions for determining and quantifying a corresponding WIP inventory driver. The method also includes executing instructions on the inputs by one or more of the modules. The inputs are applied to corresponding modules based on respective variables defined for the modules. The method further includes deriving a quantified WIP inventory resulting from execution of the instructions categorized by corresponding WIP inventory drivers.

Claims

1. A method of managing work-in-process (WIP) inventory, comprising:

receiving inputs, via a user interface of a computer processing device, the inputs corresponding to variables defined for modules, each of the modules comprising a set of instructions for determining and quantifying a corresponding WIP inventory driver, wherein WIP inventory drivers each represents distinct elements that impact at least one of acquisition, handling, and movement of the WIP inventory;

executing instructions on the inputs by one or more of the modules, the inputs applied to corresponding one or more of the modules based on respective variables defined for the modules; and

deriving a quantified WIP inventory resulting from execution of the instructions, the quantified WIP inventory categorized by corresponding WIP inventory drivers.

2. The method of claim 1, wherein the inputs comprise values reflecting a current state of a manufacturing system, the current state representing levels of WIP inventory as currently existing in the manufacturing system the method further comprising:

generating a re-usable model that represents the quantified WIP inventory derived from execution of the instructions with respect to the current state.

3. The method of claim 1, wherein the inputs comprise values reflecting a prospective state of a manufacturing system, the prospective state representing unrealized levels of WIP inventory that are based upon a prospective manufacturing plan, the method further comprising:

generating a re-usable model that represents the quantified WIP inventory derived from execution of the instructions with respect to the prospective state.

4. The method of claim 1, wherein the inputs comprise values reflecting an ideal state of a manufacturing system, the ideal state reflecting levels of WIP inventory determined to keep the manufacturing system running at a maximum capacity defined for the manufacturing system, the method further comprising:

generating a re-usable model that represents the quantified WIP inventory derived from execution of the instructions with respect to the ideal state.

5. The method of claim 1, wherein the modules include a system fill module and the variables used by the system fill module include a summation of buffering locations, an index time reflecting an average amount of time it takes for a WIP inventory material to transit the buffering locations, machine cycle times for machines located on each end of a conveyor transporting the WIP inventory material, and batch move times for load and unload batch operations, the method further comprising:

using inputs for the corresponding variables, the system fill module determines a quantity of WIP inventory materials conveyed between machines and a quantity of WIP inventory materials identified for move batching operations, and sums the total number of stations, the quantity of WIP inventory materials conveyed between machines, and the quantity of WIP inventory materials identified for move batching operations;

wherein the quantified WIP inventory resulting from execution of the system fill module includes an increase to average WIP inventory determined to maintain a percentage of uptime with respect to machines running.

6. The method of claim 5, wherein the modules include a move batching module and the variables used by the move batching module include a number of units identified in preparation for loading to an operation, a number of units collected after completion of the operation and in preparation for a next operation, and the batch moves for load and unload batch operations;

wherein the quantified WIP inventory resulting from execution of the move batching module includes any increase to average WIP inventory due to moving containers of WIP inventory materials.

7. The method of claim 1, wherein the modules include a shift pattern module, and the variables used by the shift pattern module include a time difference identified between two systems that make up the shift pattern, a frequency of occurrence of the shift pattern, and a daily demand, the method further comprising:

using inputs for the corresponding variables, the shift pattern module calculates any increase to average WIP inventory due to the shift pattern by multiplying the daily demand by the time difference and dividing a result by the frequency of occurrence;

wherein the quantified WIP inventory resulting from execution of the shift pattern module includes any increase to average WIP inventory due to disparate running times attributed to shift patterns identified for manufacturing processes.

8. The method of claim 1, wherein the modules include a planned downtime module and the variables used by the planned downtime module include a time duration of a planned downtime for an operation and a frequency of occurrence of the planned downtime for the operation, the method further comprising:

using inputs for the corresponding variables, the planned downtime module calculates any increase to average WIP inventory due to planned downtimes for each operation, and sums results of calculations for the planned downtimes;

wherein the quantified WIP inventory resulting from execution of the planned downtime module includes any increase to average WIP inventory due to planned downtimes.

9. The method of claim 8, wherein the operation subject to the planned downtime includes a model change over between part types, wherein the quantified WIP inventory resulting from execution of the planned downtime module includes any increase to average WIP inventory due to the model change over;

and

wherein further, the modules include a process batching module and the variables used by the process batching module include a daily quantity of parts pulled for each part type, a daily quantity of parts pushed for each part type, a number of days a supplier builds the part type in a specified time horizon, and a number of days a customer pulls the part type in the specified time horizon, the method further comprising;

using inputs for the corresponding variables, the process batching module calculates any increase to average WIP inventory due to process batching, comprising;

calculating a push value from the daily quantity of parts, the number of days the supplier builds the part type over the specified time horizon, the number of days the customer pulls the part type over the specified time horizon, and a push system in which the supplier produces with a greatest possible delay between production and customer pulls for the parts;

calculating a pull value from the daily quantity of parts, the number of days the supplier builds the part type over the specified time horizon, the number of days the customer pulls the part type over the specified time horizon, and a pull system in which the supplier produces the parts when the customer pulls the parts;

averaging the push and pull values;

summing averaged push and pull values for each part type; and

adding together a summed average of the push and pull values with the increase, if any, to WIP inventory due to the model change over;

wherein the quantified WIP inventory resulting from execution of the process batching module includes any increase to average WIP inventory due to process batching and model change overs.

10. The method of claim 9, wherein the modules include a customer variation module and the variables used by the customer variation module include a minimum pull size representing a value reflecting a maximum quantity of parts the customer is expected to pull based upon the daily quantity of parts pulled for each part type, a maximum pull size representing a value reflecting a minimum quantity of parts the customer is expected to pull based upon the daily quantity of parts pulled for each part type, a mean increase representing a value reflecting a predicted increase in production based on a measurable sustained increase in pulls by the customer, and a variation representing a value reflecting a calculated increase in buffer size to account for variations in customer pulls;

using inputs for the corresponding variables, the customer variation module calculates any increase to average WIP inventory due to customer schedule variations;

wherein the quantified WIP inventory resulting from execution of the customer variation module includes any increase to average WIP inventory due to customer schedule variations.

11. The method of claim 1, wherein the modules include a supplier variation module and the variables used by the supplier variation module include a daily usage variable representing a number of parts produced per part type, a late to window variable reflecting a maximum amount of time the supplier has historically been late delivering parts, and a missed window variable reflecting a number of hours between scheduled deliveries of the parts;

using inputs for the corresponding variables, the supplier variation module calculates any increase to average WIP inventory due to supplier delivery variations;

wherein the quantified WIP inventory resulting from execution of the supplier variation module includes any increase to average WIP inventory due to variations in supplier deliveries.

12. A system for of managing work-in-process (WIP) inventory, comprising:

a host system computer; and

an application executing on the host system computer, the application including modules and a user interface, the application implementing a method comprising;

receiving inputs, via the user interface of the application, the inputs corresponding to variables defined for the modules, each of the modules comprising a set of instructions for determining and quantifying a corresponding WIP inventory driver, wherein WIP inventory drivers each represents distinct elements that impact at least one of acquisition, handling, and movement of the WIP inventory;

executing a respective set of instructions on the inputs by one or more of the modules, the inputs applied to corresponding one or more of the modules based on respective variables defined for the modules; and

deriving a quantified WIP inventory resulting from execution of the set of instructions, the quantified WIP inventory categorized by corresponding WIP inventory drivers.

13. The system of claim 12, wherein the inputs comprise values reflecting a current state of a manufacturing system, the current state representing levels of WIP inventory as currently existing in the manufacturing system, the method further comprising:

generating a re-usable model that represents the quantified WIP inventory derived from execution of the set of instructions with respect to the current state.

14. The system of claim 12, wherein the inputs comprise values reflecting a prospective state of a manufacturing system, the prospective state representing unrealized levels of WIP inventory that are based upon a prospective manufacturing plan, the method further comprising:

generating a re-usable model that represents the quantified WIP inventory derived from execution of the set of instructions with respect to the prospect state.

15. The system of claim 12, wherein the inputs comprise values reflecting an ideal state of a manufacturing system, the ideal state reflecting levels of WIP inventory determined to keep the manufacturing system running at a maximum capacity defined for the manufacturing system, the method further comprising:

generating a re-usable model that represents the quantified WIP inventory derived from execution of the set of instructions with respect to the ideal state.

16. The system of claim 12, wherein the modules include a system fill module and the variables used by the system fill module include a summation of buffering locations, an index time reflecting an average amount of time it takes for a WIP inventory material to transit the buffering locations, machine cycle times for machines located on each end of a conveyor transporting the WIP inventory material, and batch move times for load and unload batch operations, the method further comprising:

using inputs for the corresponding variables, the system fill module determines a quantity of WIP inventory materials conveyed between machines and a quantity of WIP inventory materials identified for move batching operations, and sums the total number of stations, the quantity of WIP inventory materials conveyed between machines, and the quantity of WIP inventory materials identified for move batching operations;

wherein the quantified WIP inventory resulting from execution of the system fill module includes an increase to average WIP inventory determined to maintain a percentage of uptime with respect to machines running.

17. The system of claim 16, wherein the modules include a move batching module and the variables used by the move batching module include a number of units identified in preparation for loading to an operation, a number of units collected after completion of the operation and in preparation for a next operation, and the batch moves for load and unload batch operations;

wherein the quantified WIP inventory resulting from execution of the move batching module includes any increase to average WIP inventory due to moving containers of WIP inventory materials.

18. The system of claim 12, wherein the modules include a shift pattern module, and the variables used by the shift pattern module include a time difference identified between two systems that make up the shift pattern, a frequency of occurrence of the shift pattern, and a daily demand, the method further comprising:

using inputs for the corresponding variables, the shift pattern module calculates any increase to average WIP inventory due to the shift pattern by multiplying the daily demand by the time difference and dividing a result by the frequency of occurrence;

wherein the quantified WIP inventory resulting from execution of the shift pattern module includes any increase to average WIP inventory due to disparate running times attributed to shift patterns identified for manufacturing processes.

19. The system of claim 12, wherein the modules include a planned downtime module and the variables used by the planned downtime module include a time duration of a planned downtime for an operation and a frequency of occurrence of the planned downtime for the operation, the method further comprising:

using inputs for the corresponding variables, the planned downtime module calculates any increase to average WIP inventory due to planned downtimes for each operation, and sums results of calculations for the planned downtimes;

wherein the quantified WIP inventory resulting from execution of the planned downtime module includes any increase to average WIP inventory due to planned downtimes.

20. The system of claim 19, wherein the operation subject to the planned downtime includes a model change over between part types, wherein the quantified WIP inventory resulting from execution of the planned downtime module includes any increase to average WIP inventory due to the model change over;

and

wherein further, the modules include a process batching module and the variables used by the process batching module include a daily quantity of parts pulled for each part type, a daily quantity of parts pushed for each part type, a number of days a supplier builds the part type in a specified time horizon, and a number of days a customer pulls the part type in the specified time horizon, the method further comprising;

using inputs for the corresponding variables, the process batching module calculates any increase to average WIP inventory due to process batching, comprising;

calculating a push value from the daily quantity of parts, the number of days the supplier builds the part type over the specified time horizon, the number of days the customer pulls the part type over the specified time horizon, and a push system in which the supplier produces with a greatest possible delay between production and customer pulls for the parts;

calculating a pull value from the daily quantity of parts, the number of days the supplier builds the part type over the specified time horizon, the number of days the customer pulls the part type over the specified time horizon, and a pull system in which the supplier produces the parts when the customer pulls the parts;

averaging the push and pull values;

summing averaged push and pull values for each part type; and

adding together a summed average of the push and pull values with the increase, if any, to WIP inventory due to the model change over;

wherein the quantified WIP inventory resulting from execution of the process batching module includes any increase to average WIP inventory due to process batching and model change overs.

21. The system of claim 20, wherein the modules include a customer variation module and the variables used by the customer variation module include a minimum pull size representing a value reflecting a maximum quantity of parts the customer is expected to pull based upon the daily quantity of parts pulled for each part type, a maximum pull size representing a value reflecting a minimum quantity of parts the customer is expected to pull based upon the daily quantity of parts pulled for each part type, a mean increase representing a value reflecting a predicted increase in production based on a measurable sustained increase in pulls by the customer, and a variation representing a value reflecting a calculated increase in buffer size to account for variations in customer pulls;

using inputs for the corresponding variables, the customer variation module calculates any increase to average WIP inventory due to customer schedule variations;

wherein the quantified WIP inventory resulting from execution of the customer variation module includes any increase to average WIP inventory due to customer schedule variations.

22. The system of claim 12, wherein the modules include a supplier variation module and the variables used by the supplier variation module include a daily usage variable representing a number of parts produced per part type, a late to window variable reflecting a maximum amount of time the supplier has historically been late delivering parts, and a missed window variable reflecting a number of hours between scheduled deliveries of the parts;

using inputs for the corresponding variables, the supplier variation module calculates any increase to average WIP inventory due to supplier delivery variations;

wherein the quantified WIP inventory resulting from execution of the supplier variation module includes any increase to average WIP inventory due to variations in supplier deliveries.

23. A computer program product for managing work-in-process (WIP) inventory, the computer program product comprising a storage medium encoded with machine-readable computer program code, which when executed by a computer implements a method, the comprising:

receiving inputs corresponding to variables defined for modules, each of the modules comprising a set of instructions for determining and quantifying a corresponding WIP inventory driver, wherein WIP inventory drivers each represents distinct elements that impact at least one of acquisition, handling, and movement of the WIP inventory;

executing a respective set of instructions on the inputs by one or more of the modules, the inputs applied to corresponding one or more of the modules based on respective variables defined for the modules; and

deriving a quantified WIP inventory resulting from execution of the set of instructions, the quantified WIP inventory categorized by corresponding WIP inventory drivers.

24. The computer program product of claim 23, wherein the inputs comprise values reflecting a current state of a manufacturing system, the current state representing levels of WIP inventory as currently existing in the manufacturing system the method further comprising:

generating a re-usable model that represents the quantified WIP inventory derived from execution of the set of instructions with respect to the current state.

25. The computer program product of claim 23, wherein the inputs comprise values reflecting a prospective state of a manufacturing system, the prospective state representing unrealized levels of WIP inventory that are based upon a prospective manufacturing plan, the method further comprising:

generating a re-usable model that represents the quantified WIP inventory derived from execution of the set of instructions with respect to the prospect state.

26. The computer program product of claim 23, wherein the inputs comprise values reflecting an ideal state of a manufacturing system, the ideal state reflecting levels of WIP inventory determined to keep the manufacturing system running at a maximum capacity defined for the manufacturing system, the method further comprising:

generating a re-usable model that represents the quantified WIP inventory derived from execution of the set of instructions with respect to the ideal state.

27. The computer program product of claim 23, wherein the modules include a system fill module and the variables used by the system fill module include a summation of buffering locations, an index time reflecting an average amount of time it takes for a WIP inventory material to transit the buffering locations, machine cycle times for machines located on each end of a conveyor transporting the WIP inventory material, and batch move times for load and unload batch operations, the method further comprising:

using inputs for the corresponding variables, the system fill module determines a quantity of WIP inventory materials conveyed between machines and a quantity of WIP inventory materials identified for move batching operations, and sums the total number of stations, the quantity of WIP inventory materials conveyed between machines, and the quantity of WIP inventory materials identified for move batching operations;

wherein the quantified WIP inventory resulting from execution of the system fill module includes an increase to average WIP inventory determined to maintain a percentage of uptime with respect to machines running.

28. The computer program product of claim 27, wherein the modules include a move batching module and the variables used by the move batching module include a number of units identified in preparation for loading to an operation, a number of units collected after completion of the operation and in preparation for a next operation, and the batch moves for load and unload batch operations;

wherein the quantified WIP inventory resulting from execution of the move batching module includes any increase to average WIP inventory due to moving containers of WIP inventory materials.

29. The computer program product of claim 23, wherein the modules include a shift pattern module, and the variables used by the shift pattern module include a time difference identified between two systems that make up the shift pattern, a frequency of occurrence of the shift pattern, and a daily demand, the method further comprising:

using inputs for the corresponding variables, the shift pattern module calculates any increase to average WIP inventory due to the shift pattern by multiplying the daily demand by the time difference and dividing a result by the frequency of occurrence;

wherein the quantified WIP inventory resulting from execution of the shift pattern module includes any increase to average WIP inventory due to disparate running times attributed to shift patterns identified for manufacturing processes.

30. The computer program product of claim 23, wherein the modules include a planned downtime module and the variables used by the planned downtime module include a time duration of a planned downtime for an operation and a frequency of occurrence of the planned downtime for the operation, the method further comprising:

using inputs for the corresponding variables, the planned downtime module calculates any increase to average WIP inventory due to planned downtimes for each operation, and sums results of calculations for the planned downtimes;

wherein the quantified WIP inventory resulting from execution of the planned downtime module includes any increase to average WIP inventory due to planned downtimes.

31. The computer program product of claim 30, wherein the operation subject to the planned downtime includes a model change over between part types, wherein the quantified WIP inventory resulting from execution of the planned downtime module includes any increase to average WIP inventory due to the model change over;

and

wherein further, the modules include a process batching module and the variables used by the process batching module include a daily quantity of parts pulled for each part type, a daily quantity of parts pushed for each part type, a number of days a supplier builds the part type in a specified time horizon, and a number of days a customer pulls the part type in the specified time horizon, the method further comprising;

using inputs for the corresponding variables, the process batching module calculates any increase to average WIP inventory due to process batching, comprising;

calculating a push value from the daily quantity of parts, the number of days the supplier builds the part type over the specified time horizon, the number of days the customer pulls the part type over the specified time horizon, and a push system in which the supplier produces with a greatest possible delay between production and customer pulls for the parts;

calculating a pull value from the daily quantity of parts, the number of days the supplier builds the part type over the specified time horizon, the number of days the customer pulls the part type over the specified time horizon, and a pull system in which the supplier produces the parts when the customer pulls the parts;

averaging the push and pull values;

summing averaged push and pull values for each part type; and

adding together a summed average of the push and pull values with the increase, if any, to WIP inventory due to the model change over;

wherein the quantified WIP inventory resulting from execution of the process batching module includes any increase to average WIP inventory due to process batching and model change overs.

32. The computer program product of claim 31, wherein the modules include a customer variation module and the variables used by the customer variation module include a minimum pull size representing a value reflecting a maximum quantity of parts the customer is expected to pull based upon the daily quantity of parts pulled for each part type, a maximum pull size representing a value reflecting a minimum quantity of parts the customer is expected to pull based upon the daily quantity of parts pulled for each part type, a mean increase representing a value reflecting a predicted increase in production based on a measurable sustained increase in pulls by the customer, and a variation representing a value reflecting a calculated increase in buffer size to account for variations in customer pulls;

using inputs for the corresponding variables, the customer variation module calculates any increase to average WIP inventory due to customer schedule variations;

wherein the quantified WIP inventory resulting from execution of the customer variation module includes any increase to average WIP inventory due to customer schedule variations.

33. The computer program product of claim 23, wherein the modules include a supplier variation module and the variables used by the supplier variation module include a daily usage variable representing a number of parts produced per part type, a late to window variable reflecting a maximum amount of time the supplier has historically been late delivering parts, and a missed window variable reflecting a number of hours between scheduled deliveries of the parts;

using inputs for the corresponding variables, the supplier variation module calculates any increase to average WIP inventory due to supplier delivery variations;

wherein the quantified WIP inventory resulting from execution of the supplier variation module includes any increase to average WIP inventory due to variations in supplier deliveries.