Balancing workloads in an electronics assembly factory

• US 20040143352A1
• Filed: 01/17/2003
• Published: 07/22/2004
• Est. Priority Date: 01/17/2003
• Status: Active Grant

• Current Assignee: Motorola Solutions, Inc.
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Xiao, Weimin, Tirpak, Thomas, Gyorfi, Julius
• Granted Patent: US 6,829,514 B2
• Time in Patent Office: Days
• US Class Current: 700/99
• CPC Class Codes: G06Q 10/06 Resources, workflows, human or project management; Enterprise or organisation planning; Enterprise or organisation modelling
• CPC Class Codes: H05K 13/085 Production planning, e.g. of allocation of products to machines, of mounting sequences at machine or facility level

Abstract

A method of optimization of a product assembly line utilizes a mixed-integer linear programming (MILP) formulation. Line information, such as product data of products to be assembled by the line, parts data of the parts to be used to assemble the products, line data descriptive of the product assembly line and machine data of the machines of the line, is compiled and used to formulate a balancing strategy of the product assembly line (210, 240). The balancing strategy is formulated by the selective manipulation of one or more optimization variables to make the MILP closely representative of the actual manufacturing environment (240, 250, 270). Solving the MILP generates MILP output information from which output reports and metrics may be generated (270, 280).

Claims

1. A method of optimization of a product assembly line having a plurality of machines, comprising:

compiling a plurality of line information, comprising a plurality of product data of one or more products to be assembled by the product assembly line, a plurality of parts data of a plurality of parts to assemble the one or more products, a plurality of line data of the product assembly line, and a plurality of machine data of the plurality of machines of the product assembly line;

formulating a balancing strategy for the product assembly line by the selective manipulation of a plurality of optimization variables in a mixed-integer linear program (MILP);

solving the MILP to generate MILP output information; and

generating one or more reports and metrics from the MILP output information.

2. The method of claim 1, wherein formulating the balancing strategy comprises:

determining a total feeder requirement to build the one or more products from the plurality of line information; and

if the total feeder requirement exceeds a plurality of available feeders of the product assembly line, formulating the balancing strategy with a flex setup.

3. The method of claim 2, further comprising:

if the total feeder requirement does not exceed the plurality of available feeders of the product assembly line, designating one or more parts of the plurality of parts to run on one or more of the plurality of machines.

4. The method of claim 1, wherein prior to solving the MILP, further comprising:

determining whether to accept the balancing strategy; and

if the balancing strategy is not accepted, modifying one or more of the plurality of optimization variables.

5. The method of claim 1, wherein prior to solving the MILP, specifying a plurality of initial feeder assignments of one or more of the plurality of machines.

6. The method of claim 5, wherein specifying the plurality of initial feeder assignments comprises specifying one or more of a fixed initial feeder assignment and an existing initial feeder assignment.

7. The method of claim 1, wherein the plurality of optimization variables comprises one or more of part-to-station assignments, estimated workloads, changing existing setup, parts reel replenishment optimization, flexible/custom setup, feeder utilization optimization, non-bottleneck stations balancing, multi-product optimization and component constraints.

8. The method of claim 1, wherein the plurality of optimization variables comprise a total production time variable and further comprising formulating the balancing strategy for the product assembly line by the selective manipulation of the total production time variable in the MILP.

9. The method of claim 8, wherein the plurality of optimization variables further comprise a reel replenishment optimization variable and further comprising formulating the balancing strategy for the product assembly line by the selective manipulation of the total production time variable and the reel replenishment optimization variable in the MILP.

10. The method of claim 8, wherein the plurality of optimization variables further comprise a balance feeder weighting function variable added to the total production time variable and further comprising formulating the balancing strategy for the product assembly line by the selective manipulation of the total production time variable and the balance feeder utilization variable in the MILP.

11. The method of claim 8, wherein the plurality of optimization variables further comprise a balance feeder weighting function variable and an assembling time difference weighting function variable added to the total production time variable and further comprising formulating the balancing strategy for the product assembly line by the selective manipulation of the total production time variable, the balance feeder utilization variable and the assembling time difference weighting function in the MILP.

12. The method of claim 8, wherein the plurality of optimization variables further comprise an assembling process constraint variable and further comprising formulating the balancing strategy for the product assembly line by the selective manipulation of the total production time variable and the assembling process constraint variable in the MILP.

13. The method of claim 1, further comprising:

assigning the plurality of parts to a plurality of feeders of the plurality of machines in accordance with the metric information generated by solving the MILP.

14. The method of claim 13, wherein assigning the plurality of parts further comprises:

maintaining a part assignment of the plurality of parts specified in a fixed feeder setup file of the plurality of machine data and appending a plurality of remaining parts to a plurality of available locations of the plurality of feeders.

15. The method of claim 13, wherein assigning the plurality of parts further comprises:

changing a part assignment of the plurality of parts specified in an existing feeder setup file of the plurality of machine data and appending a plurality of remaining parts to a plurality of available locations of the plurality of feeders.

16. The method of claim 1, wherein formulating the balancing strategy comprises:

determining a feeder ratio of a total feeder requirement for a build on the product assembly line to a total number of available feeders on the product assembly line;

if the feeder ratio is less than or equal to a first predetermined value, formulating the balancing strategy to recommend balancing one or more non-bottleneck machines of the plurality of machines and balancing a feeder utilization of the plurality of machines of the product assembly line;

if the feeder ratio is greater than the first predetermined value and less than or equal to a second predetermined value, formulating the balancing strategy to recommend balancing the one or more non-bottleneck machines;

if the feeder ratio is greater than the second predetermined value, formulating the balancing strategy with a flex set-up.

17. A method for generating a balancing strategy of a product assembly line having a plurality of machines, comprising:

compiling a plurality of line information, comprising a plurality of product data of one or more products to be assembled by the product assembly line, a plurality of parts data of a plurality of parts to assemble the one or more products, a plurality of line data of the product assembly line, and a plurality of machine data of the plurality of machines of the product assembly line; and

formulating the balancing strategy for the product assembly line by the selective manipulation of a plurality of optimization variables in a mixed-integer linear program (MILP);

wherein the plurality of optimization variables in the MILP comprise a total production time variable and formulating the balancing strategy for the product assembly line comprises selectively manipulating the total production time variable in the MILP.

18. The method of claim 17, wherein formulating the balancing strategy further comprises:

determining a total feeder requirement to build the one or more products from the plurality of line information; and

if the total feeder requirement exceeds a plurality of available feeders of the product assembly line, formulating the balancing strategy with a flex setup.

19. The method of claim 18, further comprising:

if the total feeder requirement does not exceed the plurality of available feeders of the product assembly line, designating one or more parts of the plurality of parts to run on one or more of the plurality of machines.

20. The method of claim 17, wherein the plurality of optimization variables further comprise a reel replenishment optimization variable and formulating the balancing strategy further comprises selectively manipulating the total production time variable and the reel replenishment optimization variable in the MILP.

21. The method of claim 17, wherein the plurality of optimization variables further comprise a balance feeder weighting function variable added to the total production time variable and formulating the balancing strategy further comprises selectively manipulating the total production time variable and the balance feeder utilization variable in the MILP.

22. The method of claim 17, wherein the plurality of optimization variables further comprise a balance feeder weighting function variable and an assembling time difference weighting function variable added to the total production time variable and formulating the balancing strategy further comprises selectively manipulating the total production time variable, the balance feeder utilization variable and the assembling time different weighting function in the MILP.

23. The method of claim 17, wherein the plurality of optimization variables further comprise an assembling process constraint variable and formulating the balancing strategy further comprises selectively the total production time variable and the assembling process constraint variable in the MILP.

24. The method of claim 17, further comprising:

solving the MILP to generate MILP output information; and

generating one or more reports and metrics from the MILP output information.

25. The method of claim 24, wherein prior to solving the MILP, further comprising:

determining whether to accept the balancing strategy; and

if the balancing strategy is not accepted, modifying one or more of the plurality of optimization variables.

26. The method of claim 24, wherein prior to solving the MILP, specifying a plurality of initial feeder assignments of one or more of the plurality of machines.

27. The method of claim 17, wherein formulating the balancing strategy further comprises:

determining a feeder ratio of a total feeder requirement for a build on the product assembly line to a total number of available feeders on the product assembly line;

if the feeder ratio is less than or equal to a first predetermined value, formulating the balancing strategy to recommend balancing one or more non-bottleneck machines of the plurality of machines and balancing a feeder utilization of the plurality of machines of the product assembly line;

if the feeder ratio is greater than the first predetermined value and less than or equal to a second predetermined value, formulating the balancing strategy to recommend balancing the one or more non-bottleneck machines;

if the feeder ratio is greater than the second predetermined value, formulating the balancing strategy with a flex set-up.