Week 10: Production Planning and Control Flashcards
What is forward scheduling?
In forward scheduling tasks are completed as early as possible, this offers high labour utilisation and flexibility
What is backward scheduling?
In backward scheduling tasks are completed as late as possible, this offers lower material costs and less exposure to risks in case of order changes
What are the common sequencing rules(7)?
- Physical constraint: jobs that physically fit together may be scheduled together
- Customer priority: Important customers first
- Due Date (DD): irrespective of everything else
- Last in first out (LIFO): unloading an elevator
- First in first out (FIFO): restaurant
- Longest operation time (LOT): to have less idle time
- Shortest operation time (SOT): when cash constrained, to quickly receive payments
What are the columns in a sequencing table?
- Job sequence
- Process time
- Start time
- Finish time
- Due date
- Lateness
What is Johnson’s rule?
For 2 workstations. Look for smallest processing time, if its WS1 then put at the start, if its WS2 put at the end. Repeat
What are push production management strategies?
Push strategies are those in which the production signals are in top down manner based on demand forecasts. The signals are given to workstations which push processed parts to the subsequent workstation.
What are pull production management strategies?
Pull strategies are those in which production signals are generated downstream at point of delivery to the customer and are transferred upstream to workstations in the production systems. This is used in JIT and lean manufacturing
What is MRP?
Material Requirements Planning is a push system that utilises the bill of materials (BOM) and a master production schedule (MPS) to make timing and volume calculations to meet forecast demand
What items are calculated in MRP(5)?
- Gross requirements - the total quantity needed from the item in the time period
- Scheduled receipts - the quantity that will be received due to orders placed before the planning period
- Projected on hand inventory - the quantity of the item that is expected to exist at a given time
- Planned receipts - the quantity of items to be received in the time period as the result of the planning period
- Planned order release - the quantity that is ordered in the time period
Describe the algorithm for MRP
- Draw BOM
2. Construct MRP tables for each element from top to bottom of the BOM
What is lean production/JIT?
Lean production/Just in time is a pull approach to control. The aim of this approach is to meet demand instantaneously with perfect quality and zero waste. This involves supplying products with perfect synchronisation with the demand
What are the advantages of JIT(2)?
- Great visibility
- Solving problems at each stage is everyones responsibility
What is the disadvantage of JIT?
Less capacity utilisation, when problems occur there are no buffers so all parts of production have to be stopped
What are the basic working practices of JIT(8)?
- Discipline: in following work standards, critical for safety and quality
- Flexibility: to increase people’s responsibility to their abilities
- Equality: as one person’s problem is everyone’s
- Autonomy: delegating responsibility to people so that they can make direct decisions
- Development: a more capable workforce will increase productivity
- Quality of working life: involve people in decision making, increase job security and enjoyment of facilities
- Creativity: an indispensable amount of motivation
- Total people involvement: staff take on more responsibility dealing with the supply chain, recruitment, quality issues and spending of improvement budgets
What is continuous improvement in lean?
Continuous improvement in lean is an important principle - improvement towards the ideal ‘instantly meeting demand with perfect quality and no waste’ is a never ending process. (kaizen)
