Heijunka:
Just-in-time requires a stable production plan. If the volume or the product mix varies widely over time, it becomes very difficult to maintain a just-in-time environment. While customer demand is rarely known in advance, master production schedules are typically used to aggregate customer behavior and to govern production volume and mix for a specified time period. The master production schedule is typically given in units to be produced per week or per month. This must be further broken down to indicate smaller increments of time and more specific product identification. Heijunka boards generally show time increments of 5 - 30 minutes. The work day is divided into even time increments shown as column headings on the heijunka board. Various work areas or processes are shown as rows on the heijunka board. Each cell, then, on the heijunka board represents what is to be started by each area in each time slot. Ideally, there will be a short pattern of what is to be produced, and the pattern will be repeated throughout the day. For example, if two products of equal volume are produced, rather than producing X for four hours and then Y for four hours each day, the heijunka board would show alternating production X - Y, throughout the day.
Discuss how heijunka or production leveling is related to each of the following techniques or concepts.
- Five S
- Standardized Work
- Flexible or Cross-Trained Employees
- Kanban
- Value Stream Mapping