Method and system for scheduling a stream of products in a manufacturing environment by using process-specific WIP limits

A method of automatically controlling a process flow in a manufacturing environment, the method comprising:

• determining a plurality of sections of said process flow performed in said manufacturing environment by using a plurality of process tools for processing products, each of said plurality of sections corresponding to a group of interrelated processes;
• determining a maximum work in progress value for each of said plurality of sections on the basis of at least a section-specific characteristic and a characteristic relating to a production target value of said process flow;
• for each of the plurality of sections, comparing, in a control system, a current work in progress value of a respective section with a respective maximum work in progress value associated with said respective section to provide a comparison result;
• and
• controlling, using the control system, a flow of products to each of said plurality of sections by using said comparison result, wherein at least one process tool is used to perform a first process in a first one of said plurality of sections and a second process in a second one of said plurality of sections, and wherein said process tool is controlled to perform said second process while rejecting requests for said first process when the work in progress values of said first and second sections are higher and lower, respectively, compared to said maximum work in progress value.

A method of automatically controlling a process flow comprising a plurality of process operations in a manufacturing environment, the method comprising:

• determining a critical work in progress value for each process operation on the basis of a characteristic related to a production target value of said process flow, said critical work in progress value indicating a required work in progress value at each process operation to support said production target value;
• comparing, in a control system, each critical work in progress value with a current work in progress value of each process operation to provide a comparison result;
• when said comparison result indicates that a first process operation has a first current work in progress value that is greater than a critical work in progress value associated with said first process operation, generating, using the control system, a reduced priority value for each of a plurality of process operations preceding said first process operation;
• and
• processing products according to the plurality of process operations on the basis of said reduced priority values.

A method of automatically controlling a process flow comprising a plurality of process operations in a manufacturing environment, the method comprising:

• determining a critical work in progress value for each process operation on the basis of a characteristic related to a production target value of said process flow, said critical work in progress value indicating a required work in progress value at each process operation to support said production target value;
• comparing, in a control system, each critical work in progress value with a current work in progress value of each process operation to provide a comparison result;
• when said comparison result indicates that a first process operation has a first current work in progress value that is greater than a critical work in progress value associated with said first process operation, generating, in the control system, a reduced priority value for each of one or more process operations preceding said first process operation;
• and
• processing products according to said one or more process operations on the basis of said reduced priority values, wherein generating a reduced priority value for each of said one or more preceding process operations comprises estimating a number of preceding process operations on the basis of said comparison result and a cycle time of process operations preceding said first process operation.

A method of automatically controlling a process flow comprising a plurality of process operations in a manufacturing environment, the method comprising:

• determining a critical work in progress value for each process operation on the basis of a characteristic related to a production target value of said process flow, said critical work in progress value indicating a required work in progress value at each process operation to support said production target value;
• comparing, in a control system, each critical work in progress value with a current work in progress value of each process operation to provide a comparison result;
• when said comparison result indicates that a first process operation has a first current work in progress value that is greater than a critical work in progress value associated with said first process operation, generating, in the control system, a reduced priority value for each of one or more process operations preceding said first process operation;
• and
• processing products according to said one or more process operations on the basis of said reduced priority values, wherein said first process operation and a second process operation are performed by a first process tool and wherein the method further comprises reducing priority for performing said first process operation and increasing priority for performing said second process operation, when said second operation is not one of said one or more preceding process operations.