Often, people confuse Lean Manufacturing with Just in Time production (JIT), understanding the two concepts as they had the same meaning when Lean Manufacturing and JIT have a few similarities but are essentially different. While JIT is focused on making production processes more efficient, lean manufacturing cares about using efficiency to add value to products than can be recognized by customers, while reducing “muda” or waste along the manufacturing process. Sometimes Lean Manufacturing is dedicated to reducing JIT costs associated with transportation, warehousing and, packaging.
So, what is Just-in-Time Manufacturing?
JIT was created in Japan by the Toyota Production System. The entire concept was inspired by the form U.S. supermarkets replenish products on the shelves, providing to customers a way of interaction with products that allows them to buy what they need in the quantity they need it. Due to this dynamic supermarkets only replenish product amount in small batches according to the way they are consumed.
When JIT didn’t exist, most manufacturers kept huge inventories just in case the needed to produce something. When Toyota introduced the JIT system, they found a way to be competitive in the American market investing only in the manufacturing processes. JIT allowed Toyota to reduce lead time on orders and costs of production. This system was successful enough to be copied by other companies.
JIT can be defined as the group of ideas and practices on which a company bases its philosophy of keeping a small inventory, requiring what is needed to manufacture a specific product only when it is needed. This allows manufacturers to receive the needed raw materials even hours before starting with the production process. Also, it doesn’t keep the finished goods on a warehouse agilely shipping them to the final consumer.
One of the main concepts that characterize JIT is that production is intended to be pulled through instead of being push through. Meaning that production only takes place for customer orders, and the production cycle starts when an order has been placed by a customer. This forces suppliers to deliver raw materials when they are needed, requiring more frequency on the delivery of stocks.
What are the differences with Lean Manufacturing?
Lean manufacturing reexamined the concept of JIT thinking in how it could add value to the product keeping in mind the customers perspective. For this reason, Lean Manufacturing embraces JIT evaluating every step of the production process in order to add value through each one of them.
Another important aspect of Lean Manufacturing is that its main goal is to reduce waste along the production process, it is not only about keeping a small inventory, and it aims to enhance cost efficiency while securing a competitive advantage over other manufacturers. Reducing waste means the minimization of unnecessary processes such as extra transportations, wrapping material, extra-large location or expensive labor.
Lean manufacturing is in a larger sense an American version of Japanese JIT and Kaizen, embracing continuous improvement while measuring results, reducing inventory and streamlining a production system that adds value to products on each manufacturing step. Lean manufacturing tries to use not only a small inventory but a set of efficient workers in an efficient space, no matter if it is dedicated to a mass or a small production.
Greatly emphasizing on using a few resources, Lean Manufacturing focuses on eliminating activities that may represent a cost and don’t add value to the finished product for customers. Lean Manufacturing evaluates and reshapes the design process, the way the supply chain is managed and the relation between the company and its customers, something that JIT doesn’t consider.
Another thing that makes Lean Manufacturing different is that it uses multi-skilled workers that can operate at different functions and levels at the organization. This also applies to machines that are designed in a way they can produce a wide variety of products in smaller or bigger amounts depending on the market needs, allowing companies to have mass and craft productions at a low cost, without having to invest in specialized equipment every time they want to launch a new product to the market.
In practice, both JIT and lean manufacturing need to consider numerous conditions in order to be successfully implemented. These includes keeping small lots of finished products, agile setups and changeover times, controlling product quality efficiently and effectively and developing a production process that aims to minimize waste and maximize the efficiency of any type of labor.
David Kiger knows that in the end, both methods are pretty similar since they aim to be better and more efficient manufacturing processes, however, JIT mainly focuses on production related concepts while lean manufacturing deeply cares about what customers really want and studies different ways to create production processes that allow to developing perfect products at the perfect price.
To read more about how JIT and Lean Manufacturing differ from each other, click here.