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JUST IN TIME (JIT)
It is also called ZERO INVENTORY operation.
It is actually philosophy which can be installed after eliminating an unwanted operation.
It is a continuous process.
It seeks to eliminate raw material stock and finished stock.
It has to adhere to other norms of manufacturing excellence like right time delivery every time, perfect quality and right implementation of plan.
JIT cannot be maintained if quality components are not continuously made available.
The internal and external suppliers are the key to success in JIT system.
Quality and timely supply schedule are necessary for it.
JIT has been successfully employed in Taiwan, Korea, Japan .
On installing JIT, they have reduced inventory level of only 2 days in place of 8-12 weeks inventory levels.
JIT reduces inventory carrying costs
JUST IN TIME PHILOSOPHY The basic concept is not to make anything till it is needed.
JIT teaches us an effective method of manufacturing.
A working definition of just in time is that it is a structural approach in a manufacturing organisation focused on improving timeliness, quality, productivity and flexibility utilising various methods of work simplification and waste reduction.
In JIT, we have to meet customer’s requirement of quality, cost and delivery time.
JIT is not restricted however to manufacturing, but can be
extended to distribution, sales, marketing and finance.
WASTE DEFINITION JIT is achieved through work simplification and waste
reduction.
Waste is anything other than minimum amount of equipment, material, parts and working time absolutely essential for production. Absolute minimum resources mean for example:
• One supplier• No people, equipment or space dedicated to work• No safety stock• No excess lead times• No people doing jobs that do not add value.
MATERIAL MANAGEMNET IN JIT
The vendor plays important role in JIT. Following are the points indicating requirements:-
Total Vendor Involvement
Total Vendor Quality Control
Smooth Material Flow
BENEFITS OF JIT
Set up times are significantly reduced in the factory.
The flow of goods from warehouse to shelves improves.
Employees who possess multiple skills are used more efficiently.
JIT provides better scheduling and work hour consistency.
There is an increased emphasis on supplier relationships.
Supplies come in around the clock, which keeps workers productive and businesses focused on turnover.
For the purpose of eliminating or reducing waste “JIT” gave birth to many ‘ common sense’ techniques in the organization such as:
• KANBAN an integrated JIT system• Group technology (GT)• JIDOKA (Low Cost Automation)• Total Productive Maintenance (TPM)• Pokayoke (Mistake Proofing)• Single Minute Exchange of Dies
Single Minute Exchange of Dies
Single Minute Exchange of Dies (SMED) is the approach to reduce output and quality losses due to changeovers.
The method has been developed in Japan by Shigeo Shingo, and has proven its effectiveness in many companies by reducing changeover times from hours to minutes.
"The flow must go on", was Shigeo's reaction when he witnessed change over times of more than 1 hour. Based on his huge experience, he developed a method to analyse the changeover process, enabling local personnel to find out themselves why the change over took so long, and how this time can be reduced.
In many cases, change over and setup times can be reduced to less than ten minutes, so the change over time can be expressed with one single digit, and is therefore called "Single Minute Exchange of Dies".
Implementation
Shigeo Shingo recognizes eight techniques that should be considered in implementing SMED.
1. Separate internal and external setup operations
2. Convert internal to external setup operations
3. Standardize function, not shape
4. Use functional clamps or eliminate fasteners altogether
5. Use intermediate jigs
6. Adopt parallel operations
7. Eliminate adjustments
8. Mechanization
He suggests that SMED improvement should pass through four conceptual stages:
1. Ensure that external setup actions are performed while the machine is still running.
2. Separate external and internal setup actions, ensure that all parts function and implement efficient ways of transporting the die and other parts.
3. Convert internal setup actions to external.
4. Improve all setup actions.
Formal method:
There are seven basic steps to reducing changeover using the SMED system:
1. OBSERVE the current methodology (A)
2. Separate the INTERNAL and EXTERNAL activities (B). Internal activities are those that can only be performed when the process is stopped, while External activities can be done while the last batch is being produced, or once the next batch has started. For example, go and get the required tools for the job BEFORE the machine stops.
3. Convert (where possible) Internal activities into External ones (C) (pre-heating of tools is a good example of this).
4. Streamline the remaining internal activities, by simplifying them (D). Focus on fixings - Shigeo Shingo rightly observed that it's only the last turn of a bolt that tightens it - the rest is just movement.
5. Streamline the External activities, so that they are of a similar scale to the Internal ones (D).
6. Document the new procedure, and actions that are yet to be completed.
7. Do it all again: For each iteration of the above process, a 45% improvement in set-up times should be expected, so it may take several iterations to cross the ten minute line.
Effects of Implementation:
Stockless production which drives capital turnover rates.
Reduction in footprint of processes with reduced inventory freeing floor space.
Productivity increases or reduced production time.
Increased machine work rates from reduced setup times even if number of changeovers increases.
Elimination of setup errors and elimination of trial runs reduces defect rates
Improved quality from fully regulated operating conditions in advance
Elimination of unusable stock from model changeovers and demand estimate errors
Ability to mix production gives flexibility and further inventory reductions as well as opening the door to revolutionized production methods (large orders ≠ large production lot sizes)
