L3- Batch scheduling Flashcards
Production planning ensures
All orders met, stocks maintained, raw material procured efficiently
Utilisation
Fraction of time used over all schedule time
Optimise individual plant items
State-task network
Shows input/outputs, and intermediate flows of all materials (tasks not physical flows)
Resource-task network
Materials and equipment shown
Utilisation in terms of process tasks shown
Gantt chart options:
1) Run successive batches without overlap - each batch is complete before next begins
2) Overlap successive batches- next batch starts before preceding batch complete
Cycle time & how to reduce this?
Time between start of one batch and start of next batch
Reduced by introducing overlap
Makespan
Time required to produce a given number of batches- either one product or one sequence
Bottleneck
Production rate limited by capacity of plant item- process is only as fast as slowest stage
Breaking bottleneck
Design conditions change
Parallel reactor
In multi-product plant, a further reaction vessel can be used
Multiproduct plant
Another product run on same equipment
Flowshop
Plant manufactures multiple products but each product uses same stages in same order (multiproduct)
Jobshop
Plant produces multiple product, each using some or all stages but not in same order (multipurpose)
Campaign
Time interval which one or more production lines are dedicated to making a specific set of products
No-wait operation & impact on cycle time
Material transferred to next stage as soon as ready (necessary if products degrade/cool).
Shorter cycle time as more efficient use of resources
No intermediate storage & impact on cycle time
Batches cannot be stored in between operations- processed continuously.
Longer cycle times as time between batches increased from need to wait for previous batch before starting next batch.
