Heijunka (Level scheduling) is a
Lean method for reducing the unevenness in a production process and minimizing
the chance of overburden. The term Heijunka comes from Japanese and literally
means leveling. It can help you react to demand changes and utilize your
capacity in the best possible way. By implementing Level scheduling, you can
stop producing work in batches and start processing orders according to
customer demand. This will allow you to reduce your inventory costs as you will
have a lesser amount of goods in reserve waiting to be purchased when the
volume of orders is low.
On the other hand, your process and
team will be protected from overburden when demand spikes up as you will be
producing value according to your takt time, or simply said, your average sell
rate.
Level scheduling allows you to
produce and deliver value to your customer at a steady pace so that you can
react to fluctuations according to your average demand. For that purpose the
method has two ways of leveling production
ü
Leveling by volume
ü
Leveling by type
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Leveling by volume
When establishing a continuous flow of job,
in order to produce only what was ordered and keep your inventory costs low. In
form, Lean teaches that you should start new work only when an order arrives.
However, this may not be a option in companies that have a steady stream of new
orders and just have to adapt their workflow to meet demand. Hence Level
scheduling allows you to level your production by the average volume of orders
you receive.
For example, if your average demand
is 20 orders per week, but the number fluctuates by the day (e.g. Mon 3; Tue
10; Wed 5; etc.), it would be wise to implement Level scheduling to level the
production by volume.
This way you can establish a stable
flow of work and process 5 orders per day to meet the average demand by the end
of the week. By doing so, you will be able to keep your process running all the
time without extra pressure when the number of orders spikes up during the
week.
Leveling by type
Level scheduling is applicable when you are managing a portfolio of products as
well. It allows you to level production based on the average demand for each
product in the portfolio and organize your work around it.The principle stays
the same, you create enough of each good to meet the average customer demand
for the product portfolio.
For example, if you get 10 orders
per week for Product A, 2 orders for Product B, 5 orders for Product C, and 3
orders for Product D on average, you need to level your capacity to produce a
total number of 20 products per week.
However, in this case, you need to
use Level scheduling to level production even further so you can keep up with
the demand for each product.
Heijunka Box
A Heijunka
box is a scheduling tool used to visualize the work items that need to be
completed to meet your average customer demand. Basically, it is a system that
visualizes the orders of each product and according to the average demand, it
levels a production sequence for achieving an optimal flow. The typical Heijunka box looks like a
grid broken down by the type of product and the amount that needs to be
produced of it on each day of the work week.
The horizontal rows represent each product of the product
portfolio, while the vertical columns are dedicated to each day of the work
week. Each box serves as a container for the scheduled work items that your
team needs to complete.
The Heijunka box may be visualized
in different ways. You can either draw it on a flat surface like a wall or a
window and put work items inside as sticky notes, or even build an actual box
depending on your preferences.
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