4 - lean training - pull

8/12/2019 4 - Lean Training - Pull

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LEAN TRAINING

PULL



LEAN TRAINING

1. PRODUCTION STRATEGIES.

2. WHY INVENTORIES ARE USEFUL.

3. TYPES OF PULL.

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LEAN TRAINING

DESIGN SUPPLY MANUFACTURING ASSEMBLY DELIVER

a) Manufacturing to order:Production is planned after the reception of the order.

To do that is necessary:

• Complete Lead Time must be lower than the delivery time agreed with the

customers.

• Production capacity must be enough to cover the customer demand in a

period of time.

1. PRODUCTION STRATEGIES

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ETO: Engineer to order.MTO: Manufacturing to order.

ATO: Assembly to order.

MTS: Manufacturing to Stock.

There are different types depending on the moment of the process the order is

done.



LEAN TRAINING

b) PUSH strategy:

Production is planned according to the forecasted demand or according to the

productive resources capacity.

- Forecasted demand can change or false (the longer the forecast is done

the bigger is the mistake or the change).

- Different process steps are often governed by their own planning.- Planning variations or deviations generates non controlled inventories in

the production system.


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MRP ORDER

CUSTOMERSUPPLIERS

ORDER

Materials flow

Information flow



LEAN TRAINING

c) PULL strategy:

The production is authorized according to real consumptions, and thanks to the

information of the other parts of the production system.

- It is me main way to promote FLOW in your line.

- Connect the different processes and their variations.

- Allows to limitate the whole line inventory level.- The lower variation of the processes, the less inventory needed.

- Pull looks to produce what is necessary, when is necessary and in the

requested quantity.


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ORDER

CUSTOMERSUPPLIERS

ORDER

Materials flow

Information flow



LEAN TRAINING

PULL SYSTEM ADVANTAGES

• Only produces what is needed.

• Automatic planning.

• Synchronize the work in the whole value chain.

• Controls Work In Process (WIP): Maximum Limit.

• Controls Lead Time (LT): Less Dispersion.

• Quick response to demand changes.


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LEAN TRAINING

In the real life, there are situations (INEFFICIENCIES) which difficult ormake impossible to establish a continous flow (one by one piece):

• Processes which work using batches (Ovens, Baths...).

• Connection between processes with very different cycle time. In this

case it is not possible to balance them.

• Non dedicated processes which work for different production lines.

• Separated processes in which the big distance recomemnds a delivery

batch big enough to make a transport feasible.

• High variation processes which no warranty the continuous flow due to

lack of resources availability (failures, high change time, micro-stops,…).


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LEAN TRAINING

WATER =

INVENTORY LEVEL

ROCKS =

INEFFICIENCIES

Variations

Long

machine

change

BatchMachine

stops

Non-qualityPoor

LayOut

Inventories are the way to cover our line from the INEFFICIENCIES of

the processes, technologies, organization,..

- If we reduce the inventory level without inefficiencies reduction, our ship will not sail.

- It is a common mistake to prepare a production system without inventories (Just In Time) if there are

inefficiencies, so it is necessary to work firstly to reduce inefficiencies and later to slowly reduce the inventory

level.

CONCLUSION: The aim is to have a production system without inventories, but it is possible to use

them CONTROLLED to cover the inefficiencies, if there is a commitment to reduce them after the

improvements.


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LEAN TRAINING

SIMPLE PULL: customer process (B) communicate using a signal (trigger) that the supplier

process (A) can start to produce.

Simple pull, without inventory between processes, is only effective if the time between the

trigger launch and the moment the supplier delivers the product, is short enough to assure that

the customer is not going to wait (zero inventory would be achieved).

In other case, or if the process has too much variations or uncertainty, PULL WITH FIFOINVENTORY should be used.

3. TYPES OF PULL – SIMPLE

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SIMPLE PULL



LEAN TRAINING

PULL FIFO INVENTORY: it is like the simple, but allows a controlled inventory (maximumcapacity), in which the first unit which enters in the process would be the first to out of it. Once

the inventory reach the maximum capacity, the supplier would stop the production until the

reduction of the inventory level.

To stop the supplier production, the customer will not launch the trigger until the controlled

inventory could have free space again.

PULL FIFO INVENTORY

3. TYPES OF PULL – FIFO INVENTORY

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LEAN TRAINING

SUPERMARKET: replacement are done as in a traditional supermarket, covering the emptypositions in the shelves.

It is the as a pull system (simple or with inventories) of differents products at the same time.

If there is a appreciate distance between the supermarket and the customer process, another

trigger is used to supply the main line.

3. TYPES OF PULL - SUPERMARKET

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SUPERMARKET



LEAN TRAINING

CONSTANT WORK IN PROCESS (ConWIP): it looks the limitation of the work in processunits of a production system. It sends a trigger at the beginning of the system only when the

end of the system has finished one unit.

It is often used in complex production systems and with many production order at the same

time (I.E. machining area). It assures that there will not be more work in process order on

going at the same time than the allowed (controlled inventory), so it is a good measure toimprove the FLOW.

3. TYPES OF PULL – CONSTANT WIP.

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TRIGGER

WHEN ONE

UNIT IS

FINISHED

PROCESS ONLY

STARTS IF

THERE IS

AVAILABLE

CARDS

THE NUMBER OF CARDS IS LIMITED

FOR THE WHOLE SYSTEM

CONSTANT WORK IN PROCESS



LEAN TRAINING

TRIGGER: it is the signal used to indicate to the previous process that it has to start themanufacturing process of a new unit.

There are many different kinds of trigger, but the most common are:

a) Empty site: visual signal which is very useful when to processes are not very separated.

b) Transport empty box: it is like an “empty site”, but with the capacity to connect which are

very separated (no visual connection between them).

c) Kanban card: it is usually used with the “empty site”, and generally includes information to

the supplier process about the product to manufacture or deliver, the quantity, the

destination or another important information.

Whatever it is the trigger, must be clear, easy to use and known for all the system

participants.

3. TYPES OF PULL – TYPES OF TRIGGERS.

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