Productivity Tip 16 - Constraint-Based Scheduling

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Constraint-Based Scheduling methodologies can be used in your manufacturing business to make productivity gains at many levels.

When Operational computer systems were first developed they looked at Material Requirements Planning (MRP).  MRP is a production planning and inventory control system used to manage manufacturing processes and simulatenously address three objectives:

  • Ensure materials are available for production and products are available for delivery to customers
  • Maintain the lowest possible material and product levels in store
  • Plan manufacturing activities, delivery schedules and purchasing activities.

Evolution of MRP then extended to looking at Resource Scheduling. i.e. the Plant, Labour, and Equipment required to convert the raw materials into finished goods.  For this reason the initials `MRP' now meant Manufacturing Resources Planning and MRP was renamed MRPII.  The advantages of this development are that detailed plans could be put to the shop floor and be reported on by Assembly Step, which offers much tighter control over the plant.  Moreover loading by resource meant that capacity is taken into account. 

The main problem encountered with MRPII is that capacity is only considered after the initial MRP schedule has been prepared. It may turn out that insufficient time was allowed within the MRP schedule for the individual steps to be completed.   Therefore it was realised that throughput and component supply must also be considered to achieve the most cost effective production method.  A means of achieving this is by the Synchronised Manufacturing methodology.  Synchronised Manufacturing uses the fact that every organisation has at least one Resource which can be identified as having 'Capacity Constraint Resources' (CCR's).  Any effort in turning that Resource into a non-CCR will only result in other Resources becoming CCR's.  It is better, therefore, to control the current known CCR's and ensure that the maximum throughput is maintained.  Synchronised Manufacturing was introduced as the Theory of Constraints (TOC) by Dr Eliyahu Moshe Goldratt in his book “The Goal” which applies the theory of constraints to various manufacturing, engineering, and other business processes.

Ostendo Operations Software not only facilitates running MRP and MRPII but also addresses constraint-based Resource Scheduling by loading Assembly Orders in priority sequence against both constrained and non-constrained Resources (Labour and/or Equipment) to produce a recommended ‘Work-To’ List and Gantt Chart.

Ostendo also provides additional options for the Production Planner to adjust this priority List to take account of short-term changes such as Urgent Orders being introduced or required Inventory not being available (either as Buffer stock or simply incorrect ‘Book’ stock).  As of April 2012.

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