Multi-item multi-process lot size scheduling method

A program tangibly embodied on a computer-readable medium for multi-item multi-process lot size scheduling in a multi-item multi-process production system that uses a plurality of machines to process items corresponding to a plurality of steps during these steps, at least one machine or process enabling the items to be switched in connection with setup, the program enabling a computer to execute:

• solving an item-based one-dimensional sub-optimization problem independently of the other items, the problem being under a first constraint on machine interference between items and a second constraint that limits a work-in-process inventory to a non-negative value, the problem corresponding to a multi-item multi-process scheduling problem and being solved to make out a schedule for each item processed using the corresponding process;
• carrying out coordination required to meet the first and second constraints on the basis of an item-based solution found in the solving;
• causing the solving to be reexecuted every time the coordinating is executed;
• and
• generating a production schedule on the basis of the item-based solution found in the solving when the first and second constraints are met.

An article of manufacture comprising a computer-usable medium having computer-readable program code means embodied therein, for multi-item multi-process lot size scheduling in a multi-item multi-process production system that uses a plurality of machines to process items corresponding to a plurality of steps during these steps, at least one machine or process enabling the items to be switched in connection with setup, the computer-readable program code means in the article of manufacture comprising:

• the computer-readable program code means comprising for solving an item-based one-dimensional sub-optimization problem independently of the other items, the problem being under a first constraint on machine interference between items and a second constraint that limits a work-in-process inventory to a non-negative value, the problem corresponding to a multi-item multi-process scheduling problem and being solved to make out a schedule for each item processed using the corresponding process;
• the computer-readable program code means comprising for carrying out coordination required to meet the first and second constraints on the basis of an item-based solution found in the solving;
• the computer-readable program code means comprising for causing the solving step to be reexecuted every time the coordinating is executed;
• and
• the computer-readable program code means comprising for generating a production schedule on the basis of the item-based solution found in the solving when the first and second constraints are met.

A multi-item multi-process lot size scheduling apparatus that generates a production schedule applied to a multi-item multi-process production system that uses a plurality of machines to process items corresponding to a plurality of steps during these steps, at least one machine or process enabling the items to be switched in connection with setup, the apparatus comprising:

• optimizing means for solving an item-based one-dimensional sub-optimization problem independently of the other items, the problem being under a first constraint on machine interference between items and a second constraint that limits a work-in-process inventory to a non-negative value, the problem corresponding to a multi-item multi-process scheduling problem and being solved to make out a schedule for each item processed using the corresponding process;
• machine interference control means for carrying out coordination required to meet the first constraint on the basis of an item-based solution found by the optimizing means;
• inventory control means for carrying out coordination required to meet the second constraint on the basis of the item-based solution found by the optimizing means;
• and
• schedule generating means for generating a production schedule on the basis of the item-based solution found by the optimizing means when the first and second constraints are met.