How to handle un-level demand in a lean pull production environment
What if we unexpectedly run out
If you are in a repetitive or continuous process flow environment
then you probably aren't using a pure pull schedule anyway,
If you are able to approach the efficiencies of a pure lean environment,
then you might gamble on making small temporary inventories of your most popular offerings,
or you (more commonly) you will have your people do anything but make stock inventories.
(that might not be what your next customers want)
Your people should be trained to know
What to do to stay productive
Your lean objective
(Inventory that is sold,
Bookmark = throughput
Maximize throughput — not output
Output = dollar value of items produced
Throughput = dollar value of items produced that have been sold
What if we have a spike
In a lean environment, you should usually stick to your takt time —
trusting that demand will balance out soon.
If it doesn't — then you will revisit takt time soon.
Usually weekly, biweekly, or monthly
What if actual orders don't match
If there aren't enough actual customer orders for one product family,
then increase the other product families by equal ratios to stay as close to the plan as possible
Don't try to 'make up' for product family demand variances later.
Just return to the planned ratios as soon as possible
What if our customer demands
All customer demands are unpredictable in the short term.
Most prove quite stable when viewed within a longer time-frame,
One of the key enablers of Pull methods is 'excess capacity'
which is how you are able to profitably handle pretty wide demand fluctuations
If you experience seasonality, or other predictable phenomenon,
your lean consultant can help you devise appropriate demand-leveling strategies.
Very commonly, root cause analysis will reveal
that your demand fluctuations are caused by your own quirky practices,
Most products should be produced using heijunka load-leveling.
If production volumes for a given product line (not just a specific product) are extremely low,
then that product line should be produced using batch & queue
If, and only if, the product line survives careful scrutiny
It is a good idea to work with a qualified consultant
to explore best practice approaches for handling your unique demand patterns.
Bookmark = LevelSelling
Very commonly, Root Cause Analysis will reveal that the demand fluctuations that are disrupting the flow of your level schedule are caused by your own quirky sales practices, and/or compensation & reward measurement systems.
Level selling techniques help you identify and eliminate schedule-jerkers like:
Document the way YOU do it
This training page contains suggestions and ideas... not rules.
Whenever you want to systematize expert decision making (of any kind)...
Your weapon of choice will usually be a Decision Logic Flowchart
or a Decision Logic Tree
to clearly define the decision-making logic that you want your Scheduler to use
"What if we unexpectedly run out of orders?"
"What if the mix of product family demand isn't what we expected?"
"What if there's a storm? or the electricity goes out?"
It's your world. Use your process improvement tools to do your best to try to control it.