Lean Synchronisation and JIT Flashcards
What is the lean synchronisation principle?
Moving towards the elimination of all waste in order to develop an operation that is faster and more dependable, produces higher quality products and services and, above all, operates at low cost.
- the flow of items that constitute services and products always delivers exactly what customers want, in exact quantities, exactly when needed (JIT)and exactly where required with no waste (Lean).
What is the difference between the traditional approach and the lean approach?
The traditional approach: assumes that each stage in the process will place its output in an inventory that ‘buffers’ that stage from the next one downstream in the process. The next stage down will then (eventually) take outputs from the inventory, process them, and pass them through to the next buffer inventory. These buffers are there to insulate each stage from its neighbours, making each stage relatively independent.
The Lean approach: Here items are processed and then passed directly to the next stage in a synchronised manner ‘just- in-time’ for them to be processed further. Problems at any stage have a very different effect in such a system as they are detected immediately and is now everyones problem, increasing the chance of it being sold.
what do the three causes of waste, muda, mura, and murii mean?
Muda: are activities in a process that are wasteful because they do not add value to the operation or the customer
Mura: means ‘lack of consistency’ or unevenness that results in periodic overloading of staff or equipment.
Muri: means absurd or unreasonable. It is based on the idea that unnecessary or unreasonable requirements put on a process will result in poor outcomes
What are the seven types of waste?
- Over-production.
- Waiting time: amount of waiting time of items, disguised by operators who are kept busy producing WIP which is not needed at the time.
- Transport. Moving items around the operation, together with the double and triple handling of WIP, does not add value.
- Process.
- Inventory. All inventory should become a target for elimination.
- Motion. An operator may look busy but sometimes no value is being added by the work.
- Defectives. Quality waste is often very significant in operations.
How can waste be eliminated?
- through matching supply and demand exactly
- pull control
- Kanban’s - Through flexible processes
- reducing change-over times - through minimising variability
- level scheduling
- level delivery scheduling
- mixed modelling
- keep things simple
- adopt total productive maintenance
What are the 5 S’s?
- Sort (seiri). Eliminate what is not needed and keep what is needed.
- Straighten (seiton). Position things in such a way that they can be easily reached whenever they are needed.
- Shine (seiso). Keep things clean and tidy; no refuse or dirt in the work area.
- Standardize (seiketsu). Maintain cleanliness and order – perpetual neatness
- Sustain (shitsuke). Develop a commitment and pride in keeping to standards.
What is the theory of constraints (TOC) ?
It has been developed to focus attention on the capacity constraints or bottleneck parts of the operation. By identifying the location of constraints, working to remove them, then looking for the next constraint, an operation is always focusing on the part that critically determines the pace of output
What are the five steps in theory of constraint?
- Identify the system constraint – the part of a system that constitutes its weakest link; .
- Decide how to exploit the constraint – obtain as much capability as possible from the constraint For example, reduce or eliminate any non- productive time at the bottleneck.
- Subordinate everything to the constraint – the non-constraint elements of the process are adjusted to a level so that the constraint can operate at maximum effectiveness. After this, the overall process is evaluated to determine if the constraint has shifted elsewhere in the process. If the constraint has been eliminated, go to step 5.
- Elevate the constraint – ‘elevating’ the constraint means eliminating it. This step is only considered if steps 2 and 3 have not been successful. Major changes to the existing system are considered at this step.
- Start again from step 1.
Differences between MRP and lean synchronisation?
- Lean synchronization encourages a ‘pull’ system of planning and control, whereas MRP is a ‘push’ system. -
- Lean synchronization has aims which are wider than the operations planning and control activity, whereas MRP is essentially a planning and control ‘calculation mechanism’.
- MRP is driven by the master production schedule, which identifies future end-item demand. It models a fixed lead-time environment, using the power of the computer
- lean synchronization scheduling aims to meet demand instantaneously through simple control systems based on kanban. If the total throughput time (P) is less than the demand lead time (D), then lean synchronization systems should be capable of meeting that demand. But if the P:D ratio is greater than 1, some speculative production will be needed.
What is the difference between TOC and Lean synchronisation?
Overall objectives:
TOC: increase profit by increasing the throughput of a process or operation
LS: increase profit adding value from the customer perspective
Measures and effectiveness:
TOC: throughput, inventory, operating expense
LS: cost, throughput time, value added efficiency
Achieve this by:
TOC: focus on the constraints
LS: eliminate waste and add value by considering the entire process, operation or supply network
implementation:
TOC: five step continuous process
LS: continuous improvement emphasis on whole supply network
