A lean manufacturing concept, it levels production by both volume and mix. In contrast to pure make-to-order, Heijunka averages demand over a time frame so that a consistent production mix can be scheduled for better use of production facilities and people.
Customer demand for a certain product or product mix may spike and recede over the course of a time period, say a month. But by aligning the workload to the long-term demand, keeping a small but fixed level of inventory and sticking to a regular production schedule/mix, a company can reduce the stress on upstream processes to meet uneven demand. This also provides other benefits such as reduced inventory and a more consistent use of resources, people and machines.
Success at using Heijunka depends on factors such as: Flexible tooling of machines, training people to be flexible to enable them to move easily between jobs and product lines, reduced set-up time and standardized work. The ability to correctly predict customer demand also plays a crucial role.
Heijunka: Leveling the Load by EMS Consulting Group, September 2004. - http://www.emsstrategies.com/dm090804article.html