We are glad to have a guest writer on our blog that will explain his point of view about the Push and Pull strategy.
Quality & Process Excellence veteran, Lean Systems advisor, Change Agent & Coach, Published author & Academic Lecturer.
Push and Pull Strategy
It is easier to push than to pull a cart.
But it may not be easier (or better) to push rather than pull a manufacturing process.
What is this push manufacturing/pull manufacturing!
Consider a manufacturing process consisting of three operations A, B and C to be carried out in the sequence of A to B to C.
- PUSH is when operation A ‘pushes’ manufactured products up to the next operation (B) because so much has been produced at operation A.
- PULL is when operation B ‘pulls’ from the previous operation (A) as much as is needed by B to send to the next operation (C).
Pull manufacturing tends towards lean manufacturing.
You produce, only what you need for the customer and dispatch it immediately creating fastest throughput time and minimum in process or finished goods inventory.
A practical situation to understand.
A manufacturing process consists of eight operations starting with cutting steel strips to length, moving on to cold forming and then to welding and so on as shown below.
Cutting to length is the fastest operation while welding is the slowest operation.
All the operations subsequent to welding are slightly faster than welding.
As soon as the production plan or an individual work order was received, the production will issue all available strips and push cut to length material to downstream operations, creating an in-process inventory situation as shown below.
His contentions mainly were:
- He was freeing his labor from slitting and forming as soon as possible and utilizing them elsewhere.
- After this (crowding of inventory in slitting and forming sections) he was free to concentrate on welding.
This used to result in many obvious problems one of the major ones being ‘lack of control on no. of the product planned’. There was invariably a mismatch between the pieces planned and pieces received at welding.
Transformation to Pull
It was scheduled that slitting shall be done as per the welding requirements for the next day only and no more.
Stores would issue only a controlled quantity of steel strips.
Instead of PUSH by slitting, it became PULL by welding and all the resultant benefits of lean were obtained.
The actual business scenarios are not as simplistic and 100 % pull is likely to be a utopia.
But the organization has to keep on tending towards this utopian aim to derive the benefits associated with lean manufacturing.
The operations cannot, always be kept waiting for customer orders and then suddenly, ‘race’ to produce in time all that the customer wants.
Let us, then look at a model to get advantages of ‘pull’ with less than 100 % pull by making marketing the ‘the internal customer’.
Marketing can continue their work of forecasting and planning and place their demands on operations.
The output can be dispatched either to the external customer or to the internal customer i.e the Finished Goods store dispatch to the customer as and when ordered by marketing.
It should be noted that pull systems gel very well with Kanban and JIT.
Supermarkets are also very conducive to ‘pull’.
Virendra Kumar Gupta