Heijunka
Heijunka is a tool in the lean world that is striving for a leveled and smoothed dispatching of manufacturing demands which therefore leads to a reduction of waste. The meaning of levelling is to transform irregular incoming orders into uniform production batches. The target is to bring all demands on the smallest batch size possible based on a leveled production pattern. The Heijunka Board visualizes the predefined production plan for the production process. The beauty of it is that it enables you with little effort of control to implement a steady and synchronous flow of production.
If you are in a leading manufacturing position you already know how painful it can be to maintain a steady flow of work.
Customer demands are typically not perfectly leveled and this fluctuation needs to be translated into a defined takt that is given by your production process. To keep up with the incoming stream of orders and to avoid overproduction and therefore tied up cash, Heijunka can help you lowering the peaks and smoothing out production.
Heijunka is a well-known lean method for smoothing and reduce the over stressing of a production process. Heijunka is Japanese and means roughly translated levelling. The main reason for implementing Heijunka is a faster reaction time on fluctuating demands and improving the utilization of installed capacity.
With the help of Heijunka you minimize the sizes of batches to smallest size possible and start processing customer orders based on demand. This will support you on reducing your inventory as you will stop producing based on utilization of line capacity and then pile up finished goods without being sold.
At the bottom, Heijunka allows you to produce and deliver value to your customer at a steady pace and gives you the chance to react faster on deviations, while not overstressing the process. Therefore this method gives you always two options for levelling your production: By type or by quantity.
Balancing by type:
Go through your portfolio and define the average demand of each product. Based on the average demand the production is smoothed out to meet it. The target is to level the capacity of our line. Use Heijunka to keep up with the demands of each product of your portfolio and use it to visualize the production plan.
Balancing by quantity:
The main road blocker to establish a smooth and continuous production flow is producing in batches. The target is clear: produce only what is ordered. Therefore, Heijunka enables you to level your production by the average volume you get. By levelling your production this way, you will be able to achieve all demand by the end of the week. With the help of Heijunka you will keep your processes running without overburden it when unplanned peaks are coming in.
The Heijunka Box is a tool implemented on the shop floor in order to visualize the workload that needs to be fulfilled in order to meet the average demand. Simply spoken it has cards spread over the week for each product in a logical sequence to reach optimal flow.
The Heijunka Board
Usually the Heijunka box is set up in a matrix with the first column separated by product type for each line, the following columns are the workdays of the week. Therefore your Matrix defines Product type and the quantity that needs to be produced on a specific day. Two ways are most common, either as boxes where cards are placed in or as a board with magnetic cards that stick on it.
Depending on your installed capacity and the team size you want to cover with Heijunka you might need multiple Heijunka boards. Typically the cards you use are having the format of Kanban cards, that are following the process of the processed good until the end and then are placed back to the collection box for new planning.
Heijunka is a great lean method that allows you to organize your workflow around average customer demand. You protect your processes and employees from over stressing due to uneven production and quantity sizes. Furthermore, it supports you on realizing a complete pull system throughout production.
