Lecture 6: Requirements Planning Flashcards Preview

3P4 HUGO > Lecture 6: Requirements Planning > Flashcards

Flashcards in Lecture 6: Requirements Planning Deck (10):

How does PUSH scheduling work?

  • In a PUSH system, the orders are planned and issued centrally
  • Upon completion, the order is moved forward, until the next process is issued with the order to start processing it
  • Hence, the longest lead time process sees the new order first 
  • This is BACKWARD scheduling


What is MRP and why was it invented?

Material requirements planning

A set of techniques which uses BOMs, inventory data and the master production schedule to calculate future requirements for materials. 


Invented in '60s to cope with complexity of scheduling.

Computerised inventory control & production planning system

Schedules component items and processes when needed


Net requirements is?

Gross requirements + Allocations

On hand balance + scheduled receipts 

Net requirements


MRP can be used to generate a wide range of outputs such as:

  • Inventory order action: details of when orders for raw materials must be placed
  • Factory schedule: broad timing information on what should be occurring throughout the factory over the planning time horizon
  • Machine loading information: data on the quantity of work to be undertaken by each machine
  • Rescheduling data: given some discrepancy between reality and the schedule, the MRP system can indicate precisely what will be affected by late completion of some component


Limitations to MRP

  • Assumes infinite capacity
  • Works with fixed lead times and fixed batch sizes
  • Has no feedback - having issued the plan assumes it will work
  • Forecasting data may not be accurate
  • Inventory levels may not be accurate
  • Any delay prior to assembly will prevent completion
  • MRP pushes production so can distort demand patterns in supply chain


Explain Just in Time scheduling

Production orders are based on replenishment

Demand signal is conveyed via kanban cards

System is tightly controlled, as it is fragile, (unable to cope with large swings in volume/product mix)

Requires suppliers to deliver components using JIT

Need to keep schedule variability within 5-10%


Explain the push pull system


What is OPT

Optimised production technology

Further production planning/control/scheduling approach:

Main concept is importance of bottlenecks

  • Protect throughput at bottleneck
  • Bottleneck becomes pacemaker
  • Every minute not used at constraint is a minute lose


Explain the different aspects of MRP, JIT and OPT