Heijunka, a Japanese word that means leveling, is an important concept in lean methodology that can help eliminate...
waste and better meet customer demand.
Pioneered by the Toyota Motor Corporation, Heijunka -- also known as production leveling or production smoothing -- has seen widespread adoption in the automobile industry and by companies that use repetitive manufacturing types. Many other manufacturers can also use Heijunka to optimize resources and react more quickly to customers' changing demands and supply disruptions.
Heijunka uses the Every Part, Every Interval (EPEI) approach to its production, which means producing as many in-demand products as possible in the shortest possible time, while also taking the resources' capacity situations into account.
Many companies may overlook their access to this powerful tool -- indeed, the SAP ERP Central Component (ECC) includes Heijunka as a standard feature. To set up Heijunka in ECC successfully, you'll need to focus on the following four areas.
To set up EPEI -- that is, for systems to prioritize which parts to produce and when -- requires the following configuration settings.
- Procedure profile: This step stipulates choosing Heijunka, or production leveling, to sequence the planned orders.
- Planning profile: This step includes creating a planning profile (see Figure 1), and then assigning an already created procedure profile to the planning profile.
- Setup group category and setup group key: There's no option in ECC to define the priority of the products to produce. But with these two configuration steps, managing product prioritization is possible.
- Dispatch sequence: This step stipulates the business logic based on the specific product mix that needs to be sent to different production operations for processing.
Heijunka uses takt-based scheduling; this is scheduling based on the amount of time it takes for a product to be produced or assembled on a production line. Takt is the German word for heartbeat or rate time. Takt-based scheduling includes the following.
- Work center: A work center can be a machine or group of machines that add value to a product. It's the work center that contains not just the details of a company's factory calendar, such as holidays and other off days, but also shift details and capacity details. Too many capacity planners make the mistake of maintaining a machine's ideal or theoretical capacity, which can lead to the system reflecting the incorrect capacity available for production. It's best to maintain actual machine capacity to ensure production leveling is as practical as possible.
- Line hierarchy: A line hierarchy is an assembly line consisting of all the previously created work centers. It denotes the sequence of manufacturing operations. A line hierarchy is especially important for its ability to identify a work center's bottleneck capacity and to ensure production leveling, or Heijunka, accordingly. This is known as line balancing.
- Rate routing: This feature maintains the rate at which a product is produced in a hierarchy, as above, and also automatically calculates the takt time to provide visibility between planned production time versus actual time.
The business transactions or processes in Heijunka are as follows.
- In the Heijunka Planning Board (Transaction CM25), it is possible to use a Strategy Profile to make specific settings that promote production or capacity leveling. For example, an option such as setup time optimization enables the production of the same product together for various manufacturing orders over a specific timeframe to save time, effort and resources in setting up the production line.
- Another invaluable option in the Strategy Profile is the close gap that ensures all production operations are synchronized to take maximum advantage of available machine capacities and to produce products as quickly as possible by closing as many gaps among production operations as possible.
- The Dispatch Sequence option (see step 4 of the configuration section above) uses the configuration settings completed earlier for setup group category/setup group key to align production steps to Heijunka.
- The Heijunka Planning Board also provides visibility on materials availability to ensure there are no material shortages during production.
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