In 1953, Toyota Motor Company implemented the just-in-time (JIT) production concept in a large scale to reduce waste of capital, manpower, and materials in manufacturing. The concept originated in the United States. The JIT approach aims at:
- Just-in-time delivery of supplies
- Make subassemblies from just-in-time parts
- Subassemblies are produced just in time for assembly
- Ready-to-sell finished products.
just-in-time (JIT) production
Manufacturing traditionally involves producing parts in batches, placing them in inventory, and using them as needed. An inventory-driven approach is called a push system, and parts are manufactured according to a schedule and then put into stock, ready for use when needed.
As opposed to JIT, it is a pull system, with parts produced as needed, followed by final product assembly matching demand.
Stockpiles do not exist, and the ideal production amount is one. Stockless production, JIT, and demand-driven production are also terms for JIT. In addition, parts are inspected immediately after manufacturing and use within a short period of time. This method allows workers to maintain continuous production control, identify defective parts immediately, and reduce the variation caused by the production process.
It is also important to note that, in order for JIT to be implemented successfully, it is imperative that all aspects of manufacturing operations be monitored and reviewed in order to eliminate any operations or resources which are not contributing to the value of the product.
As part of this approach,
- (a) pride in the production of high-quality products is emphasized,
- (b) idle resources are minimized, and
- (c) teamwork between workers, engineers, and management is emphasized to solve problems quickly.
It has been compared to identifying production problems based on the change in water level in a lake (representing inventory levels) when boulders cover a bed of water (representing production problems). A high water level (similar to high inventories associated with push production) prevents boulders from being exposed.
Contrary to this scenario, a low level (nearby to the low inventories of pull production) results in the boulders becoming visible and thus identifiable and able to be removed. The analogy suggests that high inventories can mask manufacturing and quality problems with parts that have already been manufactured and are already in stock.
It reduces or eliminates in-plant inventory by requiring timely delivery of parts and supplies from outside the company and from other divisions. On a daily basis, suppliers are expected to deliver pre-inspected goods to the factory in order to meet the needs of production and assembling.
As a result of this method, the company has to find reliable suppliers, maintain close cooperation and trust between its suppliers, and ensure that the distribution system it has is efficient and reliable. The number of suppliers of the company is also a crucial factor for smoother operation. The annual sales of Apple Computer went from 280 to 60 due to a reduction in supplier numbers.
JIT’s advantages. Listed here are its major advantages:
- Low cost of holding inventory
- This results in a low scrap loss since defects can be detected quickly during production or delivery
- Parts can be inspected and reworked less often
- Low-cost products of high quality
Just-in-time production has reduced production costs by 30 to 40%, inventory by 60 to 80%, rejection rates by 90 percent, lead times by 90 percent, and scrap, rework, and warranty costs by 50 percent. Indirect-labor productivity has also increased by 30 to 50%.
In today’s manufacturing environment, companies have to listen to the demands of the customers and make sure their products meet their individual needs as well as meeting the fluctuating demands of the global market. To ensure that a manufacturing enterprise is competitive, it is important that the enterprise is run with minimal waste of resources whenever possible. Lean manufacturing or lean production strategies have evolved as a result of this realization.
The following steps are involved in lean manufacturing:
Lean thinking begins with a customer-centered approach, which is only possible through a customer-focused approach. Providing the wrong product or service, even if it is efficiently provided, will waste time and money. Organizations must produce the goods and services their customers want. Optimizing processes to maximize value-added needs to be applied to all manufacturer’s activities. An activity can be assessed according to this viewpoint by:
- Exhibits clear value.
- Is of no value, but ought to be done.
- Does not add any value; it can be avoided.
Identify value streams
As part of the value stream, all activities required to produce a product are included, such as:
- Tasks related to product design and development, including the entire design process, from conception to product launch;
- Information management, which includes order taking, schedules, and deliveries;
- Tasks that enable raw materials to become finished products in the customer’s hands.
There are many to note that there can be no one person who is accurately described as a car, boat, or airplane manufacturer. These products are produced through organizations or systems that often become unwieldy and complex, with tasks that do not add value. It is possible to identify and eliminate those tasks by identifying value streams.
Flow the value stream
When producing small lots, flow is harder to achieve than when producing large lots. A just-in-time approach is essential so that there is no batch production. As such, manufacturing cells are the most logical solution, where switching between products is as quick and as easy as possible, and a production line encounters continuous flow.
Establishing just-in-time approaches to manufacturing requires the following in addition to just-in-time programs:
- Waiting time can be eliminated. An unbalanced workload, maintenance issues, or quality problems can cause a customer to wait. As a result, workers must always be as efficient as possible.
- Eliminate redundant steps and processes, because they are expensive.
- Aim to minimize or eliminate product transportation, since it represents a non-value-added activity. By providing machining cells, for example, we can either eliminate or minimize this waste. In order to identify time and motion inefficiencies, time and motion studies are done.
- Removing defects from parts.
Create a pull
The reduction of inventory, as well as order processing, physical production, and product development, is significant once value streams start flowing. Some cases have observed 90 percent reductions in physical production. In these circumstances, pull manufacturing may be possible, where products are made based on orders from customers and not in batches of unused products.
Every organization needs to improve continuously. It has been found that continuous improvement through lean manufacturing is accelerated, allowing wasteless production. As an additional benefit of lean manufacturing, firms experience the concept of kaikaku, which means “radical improvement.”