Toyota defines Heijunka as the overall leveling, in the production schedule , of the volume and variety of items produced in given time periods and adds that it is a pre-requisite for just-in-time delivery.
The basic Japanese translation of Heijunka, is “levelization.”
Production leveling, as it is also referred to is essential to any Lean facility in their pursuit to eliminate waste and improve their production efficiency. Demands frequently change and without the means to adjust, organizations will continue to fail to meet the customer’s demands, or lack their of.
No matter what industry you’re in, you will undoubtedly experience fluctuations in customer demand. Whether it’s seasonal or market influenced, you have to be prepared for change. What we’ve often seen in build-to-order approaches is a “hurry up, then slow down” attempt at meeting the changing demands of a customer. This leads to an uneven production schedule that produces more inventory than needed, overtime expenses, and the added stress on the employees and equipment that have to handle a rush of orders one week, only to be laid off the next. This is exactly the type of environment Heijunka aims to avoid.
Heijunka allows you to level your production in both volume and product diversity. Lean facilities that have implemented Heijunka, don’t base their production off the actual flow of customer orders. Instead, the company will use the Heijunka methodology to calculate the total volume of orders place in a specific time frame and level them out. This allows the facility to produce the same amount and mix each day, without the ebbs and flows of demand cycles.
Balancing your workflow has many benefits to your organization. For instance, if you have an above average week of orders, followed by a below average week, you end up paying overtime the first week and sending employees home the following. This is waste in the simplest form, that could have been avoided with Heijunka.
Heijunka has two basic objectives.
- Stabilize and standardize work flow
- Assemble alternate models on the same line while eliminating waste along the way
The slower but consistent tortoise causes less waste and is much more desirable than the speedy hare that races ahead and then stops occasionally to doze. The Toyota Production System can be realized only when all workers become tortoises.
Consistency is key with Heijunka. The strain that comes with peak ordering times is alleviated and the downtime associated with low ordering times is thus eliminated. Instead, you have a constantly working production line, working at the same pace, throughout the year.
Benefits of Heijunka:
- Customer demands are met in total over a given period of level production.
- Work schedules are predictable and can be planned accordingly.
- Avoid paying overtime.
- Finished goods inventory is in place to meet periods of high demand.
- Less strain on employees, keeping them happy and productive.
You can’t just flip a switch and implement Heijunka. It takes a lot of discipline and even more planning to be successful. You need accurate customer data which can help provide the information you need to project certain events.
With the right information and the right culture behind you, Heijunka can be a key pillar in your Lean organization. But it’s not for everyone. You need to understand your business and your customers to determine if Heijunka is right for you.