Lean Manufacturing is one of the great manufacturing models of today and we have already talked about it on several occasions. Today we are going to stop at one of the bricks that usually make up the Lean manufacturing and Just in Time building: the Heijunka. This technique of Japanese origin, which can be translated as production leveling, is created to try to mitigate the effects of variations in demand in the production chain.
This leveling refers to a more balanced production among numerous SKUs, instead of dealing with large quantities of the same SKU until moving on to the next, within a usually smaller number of SKUs.
One of the first questions that arise when we are faced with a new production model is what needs it responds to. That is, why and for what should I switch to the Heijunka?
This leveling of production is opposed to the traditional production system, focused on the manufacture of large batches of a single reference. The traditional approach is especially useful when we have to serve very large quantities or supply very stable markets with few variations in demand. For its part, the Heijunka system seeks to create productive environments that have a greater response capacity for current markets, in which demand, consumer tastes and constant product rotation are increasingly present.
When a company decides to bet on knowing the demand in real time and making its production more flexible, it must be aware of the effort and resources that it must allocate to achieve it.
As we have said, this does not mean that the Heijunka is a “better” system as such, but that it may be more suitable for certain sectors, markets or companies. For example, for companies that work with very large batches of few SKUs and seek to benefit from economies of scale, Heijunka may not be the most suitable. However, it can be for a company that, instead of wanting to produce 1,000 units of its three references, wants to be able to quickly adapt in small batches of 50 units across dozens of references, while introducing new products or adapting production quantities.
The Heijunka philosophy involves adapting the company in order to achieve this leveling in the production plan and in the product mix. This has implications for information systems, traceability, visibility of the supply and production chain, manufacturing layout (the scheme according to which we have the machines and facilities to manufacture our products), etc.
In the Heijunka, the use of the work cell is common, “which responds to the concept of the flow of very close activities and which adopts the physical shape of a “U”. The continuous flow transforms several processes that work independently into a joint and flexible work cell, where all processes are linked one after the other. The distribution in form of U gives more flexibility to the line [of production] and demands a greater polyvalence of the user”.
Among the main benefits of a successful Heijunka application are:
Reduction in the amount of inventory needed by better responding to actual demand.
Decrease in storage expenses due to the reduction in the amount of product in stock and in processing.
Better response to market variations, demand and customer requests.
Reduce excess production.
Improvement of opportunity costs, by having less amount of capital leveraged in raw materials, stocks, etc.