Job Switching in SMD Mounting Lines
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Solution Overview
Problem
In mounting lines, continuous setup changes are hindered when specific combination components, such as LEDs and current limiting resistors, are mounted on separate machines, leading to production delays due to uncertainty in the second component's resistance value until the first component is set, necessitating a more efficient job switching method.
Innovation Solution
The job switching method involves two phases: first job switching for the upstream machines to complete production and setup changes before starting the second type's production, and second job switching for downstream machines to initiate production after setup changes, allowing parallel processing and minimizing delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If continuous setup change is performed in all mounting machines, then productivity is improved, but reliability deteriorates when combination components are mounted on separate machines
Solution Approach 1:
The mounting line is divided into multiple mounting machines (first mounting machine, second mounting machine, etc.) that can operate independently. Each machine can perform setup changes at different times based on its specific requirements, allowing the system to segment the production process into reliable units while maintaining overall productivity.
Solution Approach 2:
The patent implements dynamic job switching where the production schedule is adjusted based on real-time status of each mounting machine. When continuous setup change is not feasible due to combination component constraints, the system dynamically modifies the production sequence to maintain reliability while minimizing productivity impact.
2Reliability
If setup change is performed after waiting for production completion, then reliability is improved, but loss of time increases
Solution Approach 1:
The patent performs preliminary setup changes in mounting machines that do not have combination component constraints while the previous production is still completing. This preliminary action allows these machines to be ready for the next job type in advance, reducing the overall production delay when switching between board types.
Solution Approach 2:
The system maintains continuous useful action by having different mounting machines operate at different stages of their production cycles. While some machines complete current production before setup change, others can begin setup changes earlier, ensuring that the overall line maintains continuous productive activity without complete idle periods.
3Reliability
If second component is determined after first component is set, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent introduces a control device that acts as an intermediary between mounting machines. This control device manages the coordinated setup changes across multiple machines, tracking which components have been set and determining subsequent component requirements. The intermediary handles the complexity of coordinating combination components while maintaining reliable matching between paired components like LEDs and current limiting resistors.
Data Source
AI summary
In a job switching method, when switching jobs, a first job switching is performed for a first mounting machine group from the most upstream mounting machine to a predetermined downstream mounting machine among multiple mounting machines constituting a mounting line, and a second job switching is performed for a second mounting machine group located downstream from the predetermined mounting machine. In the first job switching, jobs are switched so that production of a board of a second type is started after production of a board of a first type is completed in all the mounting machines in the first mounting machine group and a setup change is completed at least in a specific mounting machine in the first mounting machine group. Meanwhile, in the second job switching, jobs are switched so that the production of the board of the second type is started after a setup change is executed in an upstream mounting machine on which the production of the board of the first type is completed, in parallel with producing of the board of the first type by a downstream mounting machine in the second mounting machine group, and the setup change is completed.