With continuous improvement and lean management, Toyota attained the level of efficiency that declared it a leader in the automobile industry. Being crowned the world’s best-selling automaker for the 3rd time in 2022 is an outstanding achievement.
Raising TPS to such heights wasn’t possible without lean management, Heijunka, and its lean siblings.
Manufacturers often face two common challenges: producing too much, which creates waste, or producing too little, which leaves customers dissatisfied and orders not filled
Imagine figuring out a middle way that balances both these extremes and results in efficiency, customer satisfaction, and zero or minimum waste.
That’s what Hejiunka does: level production to achieve efficiency and balance!
In this guide, we’ll walk you through everything you need to know about Heijunka: what it means, how it works, and why it matters.
So, let’s scoot through Hejunka to learn everything about it, from A to Z.
What is Heijunka?
Heijunka is a Japanese term meaning “Leveling.” Heijunka focuses on leveling production, which is what the terminology conveys.
Before we explain it further, you need to learn about two more terms here:
Peak: It refers to the time when the production volume is higher than usual. Correlate it to the general meaning of peak.
Valley: This presents the citation when the production volume is far lower than usual. Consider a valley that wells down, surrounded by huge mountains.
So, Heijunka means leveling production, which refers to the plant’s production volume being kept at an average rate. This rate should be based on previous customer demands to avoid peaks and valleys.
The Story of Heijunka’s Origin
The credit of Heijunka, like the other lean management tools Kaizen, Jidoka, and JIT, goes to The Toyota Production System. Back in 1956, Taiichi Ohno, one of Toyota’s industrial engineers, took a trip to the U.S.
He studied American manufacturing processes, noted certain things, and realized there was room for improvement. He also decided to implement these new learnings and upgrade once he was back in Japan.
Besides manufacturing units and factories, the American supermarkets caught his attention and flattered him. He noticed customers simply “pull” products off shelves, which the store employees would later restock.
These observations laid the foundation of lean management, with Heinjuka being the main tool. The birth of lean management was a breakthrough at that time.
Deryl Sturdevant, a former president and CEO of Canadian Autoparts Toyota, once shared these revolutionary results of lean management.
According to him, TPS dramatically boosted production efficiency. Changing the die to make an aluminum alloy wheel typically takes 4 to 5 hours. However, this time was reduced to just an hour after the complete implementation of the Toyota Production System.
Understanding Heijunka’s Production Levelling Through an Example
Let’s say your facility produces custom garden sheds. Your production unit and showroom operate six days a week, from Monday to Saturday. The table here represents the number of shed orders received last week.
| Day | No. of Orders |
| Monday | 4 sheds |
| Tuesday | 6 sheds |
| Wednesday | 3 sheds |
| Thursday | 8 sheds |
| Friday | 14 sheds |
| Saturday | 20 sheds |
In total, you received 55 orders in the previous week. The table clearly shows that the number of orders on Friday and Saturday is significantly higher.
So, what should you do here as a plant manager?
- Deliver sheds instantly without keeping the customers waiting.
- Avoid overburdening your team when responding to high-demand days such as Friday and Saturday.
Applying Heijunka
The goal here is to level production without overburdening the workforce and machinery. To level production, divide the total weekly demand by the number of days your plant operates.
To level production, you can divide the total weekly demand by the number of days your plant operates.
Daily Production Target = Total Weekly Orders / Operating Days = 55 /6 = 9.17 or 9 sheds
By producing a steady 9 sheds per day, you:
- Maintain consistent workloads for your employees.
- Avoid wasting resources
- Efficiently utilize production capacity without overburdening the manufacturing unit and workers.
- Prepare for weekend orders proactively throughout the week.
- Avoid the last-minute chaos to meet customers’ demands.
A possible outcome is producing a surplus of sheds to meet higher weekend demands. For instance, a shed produced earlier during the week can fulfill bulkier orders on Fridays and Saturdays.
Real-Life Heijunka
The example described above has explained Hejiunka most simply. However, real-life situations are more challenging, where production leveling is complicated.
Here are the factors that contribute to the situation’s complexity:
- Product Diversity
- Varying Production Machinery
- Demand Variability
Why Hejiunka? Understanding its Effectiveness
Leveling production or Heijunka is an effective strategy. Besides making the process predictable, it keeps your workforce and machinery in good shape. Here’s how:
Since leveling production is another name for finding a balance between overproduction and underproduction, the same concept applies to the use of machinery and workforce.
Some days, your overworked employees will be drained, which can negatively impact their mental and physical health (in case of overproduction). According to the National Safety Council, fatigue-related issues cause 13% of workplace injuries in the U.S.
On the contrary, on days with less workload, workers sitting idly is also a bad idea. This doesn’t justify the working environment, the salaries and wages that they get, or their services.
Now, apply the situation to machinery. Overusing machinery will lead to breakdowns, and irregular use due to fluctuating demand can negatively impact the machine’s life.
Two Ways of Level Production
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Levelling by Production Volume
This is the most straightforward sort of leveling. It features visualizing the number of orders in a certain time period on a table.
Once the customer data and time period are tabulated, you can apply the formula to calculate your optimum production volume.
Optimum Production Volume = No of Customer Order / Time Period
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Levelling by Product Type
This method is more advanced than leveling by volume. It is used for manufacturing facilities that produce multiple products. Unlike leveling by production volume, it involves an extra variable, the product variation.
The formula for production volume is the same. The only difference is that it is calculated for every product produced in the manufacturing unit.
Heijunka Tools / Heijunka Board Examples
Implementing Heijunka becomes efficient by utilizing Heijunka tools. They behave like GPS on the manufacturing floor, giving you the exact locations of the products throughout the manufacturing process. Let’s have a look at these.
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The Heijunka Board
A Hejunka board or box is one of the most popular tools for production leveling. Consider it a shelf with many compartments. The horizontal excess across the top represents time, which could be hours, days, weeks, or months.
The vertical axis lists the different products that your plant manufactures.
Working if Heijunka Box
When starting production for a product, put all the relevant documents into a brightly colored folder.
- Place the folder in the correct box on the shelf.
- Once the product is finished, remove the folder.
Using bright-colored folders makes it easy for employees to spot what’s happening while moving around. At a glance, they can quickly see how many products are being worked on during the designated time period, which is based on the number of folders in the boxes.
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The Kanban Board
Kanban board is another incredible tool that streamlines your production. It focuses on the stages of the production process. Here are the four stages that a Kanban board indicates:
- To do: Tasks that need to be done
- In progress: Tasks that are currently being worked on
- In review: A stage in the lifecycle of a task
- Complete: Tasks that have been completed / Stuck
Steps for Using Kanban
- Write down the name of each product on a sticky note.
- Place the sticky note in the appropriate section on the board. It depends on where the reproduction occurs.
- Move the sticky note as the production progresses into the upcoming sections.
This is how everyone gets a quick update on the location of each product in the process. For instance, if there are too many sticky notes in the stuck section, it’s evident that some problems should be immediately addressed.
The Kanban board gives everyone a quick visual update on where each product is in the process. For instance, if there are too many post-its in the Backlog section, it signals that something needs attention.
How to Achieve Heijunka Flow
Achieving a true Heijunka isn’t a walk in the park. Dedication to lean practices and a consistent commitment to improvement are the conditions that must be fulfilled.
Achieving leveled production is seen as a milestone achieved in mature lean implementation.
However, companies that have managed to make a mark often pair this approach with other effective practices.
| Single Minute Exchange of Die or SMED | Used for quick tool and equipment changes. |
| Small Batch Sizes | This approach focuses on producing in smaller quantities and aims to reduce waste. |
| Kanban System | A production system strictly aligned with customer demand. |
| Knowing Your Customers | Truly understanding their needs and timings |
Working toward Heijunka also requires you to follow the following steps.
Step 1: Standardize Work
Begin with a schedule for consistent work. This is crucial for identifying underperforming areas that need improvement and making operations predictable.
Work can be standardized by:
- Understanding the difference between internal and external tasks
- Practicing operating procedures until they are second nature (involving multiple operations)
- Handling errors systemically and efficiently.
Step 2: Improve Takt Time
Takt time refers to the rhythm of your customer’s buying habits. It involves your response to their needs. Elaborating on this, takt time tells you how often you need to produce a product to fulfill customers’ needs.
Here’s how working on takt time can ultimately contribute to mature Heijunka:
| Understand Your Customer Buying Rate
When do they need your product? |
Use Kanban
Manage both the work and materials based on customer orders. |
Step 3: Sequence Your Work
Sequencing facilitates leveled production! It focuses on small-batch production. Here’s what to do:
| Follow the Order Sequence | This refers to producing and delivering the items in the same order they’re placed. |
| Switch Between Tasks Quickly | Use SMED to rapidly change tools and switch between product types. |
Key Takeaway
Meaning of Hejunka? Leveled production! This excellent lean tool streamlines your manufacturing by balancing overproduction and underproduction. If you’ve been facing these extremes, implement Heijunka to enjoy the following.
- Lower Costs
- Better Customer Service
- Smarter Supplier Communication
- Happier Employees
If you’re ready to overcome production challenges, Heijunka is the solution to streamline operations and drive success.
