Heijunka is a japanese term that can be translated as product smoothing or load leveling. The heijunka technique is used to assist and in many ways facilitate Just in time production. Heijunka is often used to smooth out production both internally and externally. Heijunka gives organizations the ability to efficiently and effectively meet customer demands without having to produce excessive batches of work. Additionally heijunka helps to keep inventories to a minimum level, lower holding costs, increase resource power and improve the overall lead time of an organization.
Example of Heijunka Board:
As you can see in the photo above heijunka helps us to understand our production sequence in terms of both volume and style of product.
Volume Leveling: To level production by volume or quantity a Takt Time must be established. Establishing Takt time helps us to understand how many units we need to make and in what amount of time each of the individual units needs to be made in.
Style/Quantity Leveling: When looking to level production based on style or quantity you must also first understand what the Takt Time is first. Traditionally using a batch production approach understanding the time it takes to keep up with demand helps you to calculate the appropriate number of resources at each station, however this often results in batched production which builds a lot of waste into the process. The key to leveling style or quantity is being able to answer the question; where is the waste in the process? Some common examples of waste are slow changeovers excessive waiting, overproduction, and motion. Once you have identified the waste in the process you can then begin to reduce changeover times, transportation, inventory (batching), overproduction (batching) and any other of the 8 forms of waste you may have discovered. This gives companies the ability to reduce batch sizes and establish tactical production buffers so that lines do not lag behind or worse yet shutdown.