Just In Time Manufacturing: Definition, Concept, Advantages & Disadvantages [With PDF]

Definition of JIT:

A corporate system that is designed to produce output within the minimum lead time and at the lowest total cost is the definition of Just In Time Manufacturing (JIT) and it is also known as just-in-time production or the Toyota Production System.

Concept of Just In Time Manufacturing:

Just in Time Manufacturing mainly focus on the following aspects:

  • What is JIT?
  • Focus of JIT
  • Seven basic types of wastes
  • Objectives of JIT
  • Just in Time Philosophy
  • Differences between Traditional & JIT etc. 

1. What is JIT?

A corporate system that is designed to produce output within the minimum lead time and at the lowest total cost is the definition of Just In Time Manufacturing (JIT).

just in time manufacturing
Credits : theinvestorsbook.com

2. focus of Just In Time Manufacturing:

The focus of JIT is Variance and Waste. The focus of JIT is to improve the system of production by eliminating all forms of wastes.

3. 7 Basic Types of Wastes:

The seven basic types of waste are:

  • Transportation waste
  • Process waste
  • Inventory waste
  • Waste of motion
  • Waste from product defects
  • Waiting time
  • Overproduction

4. Objectives of JIT:

These are the following objectives of JIT:

  • You need to produce only those products that the customer wants.
  • Produce with perfect quality
  • Produce with a minimum lead time
  • Produce products with only those features that customer wants.
  • Produce products only at the rate of customer need.

5. Just in Time Philosophy:

The philosophy of Just in Time can be traced back to Henry Ford but formalized JIT originated in Japan as the Toyota Production System. W. Edwards Deming’s lesson of variable reduction was a huge influence.

The 7 zeros:

To identify the targets of waste reduction following are the 7 points that need to be considered:

  • Zero lot size: To avoid delays in batching 
  • Zero Defects: Quality at the source
  • Zero Breakdowns: To avoid stopping tightly coupled lines.
  • Zero Surging: It should be necessary for the system without WIP buffers.
  • Zero Setups: Allow production in small lots to minimize setup delay.
  • Zero Handling: To promote the flow of parts.
  • Zero Lead Time: The rapid replenishment of parts must be ensured.

The Environment as a control:

A JIT environment requires that management control process aspects that formally were considered beyond control.

Constraints or Controls:

  • Machine setup times
  • Vendor Deliveries
  • Quality levels (Scrap/rework)
  • Product Design
  • Production Schedule (ex. customer due dates)

6. Differences between Traditional Manufacturing & JIT Manufacturing:

In Traditional Manufacturing:

  • Goal: By minimizing disruptions, you can maximize production 
  • Management Assumption: “We can sell what we make”
  • Spread resources evenly: Line balancing
  • Dependable and efficient operations: Automation and Forecasting
  • Decouple Operations: Line pacing and extensive scheduling

In JIT Manufacturing:

  • Goal: Produce goods that are ready to sell quickly and efficiently.
  • Management Assumption: “We make what we can sell
  • Flow Manufacturing: GT/CM and cross-training
  • Level production with visual control: JIT, SPC, Kanban
  • Clean up the workplace(5Ss)
  • Manpower Reduction.

Video by Prof. Inderdeep Singh on JIT Manufacturing:

Just In Time Stock Replenishment:

It is all about having the right goods/products at the right place, at the right time, and in the exact amount without the safety net of excessive inventory. 

Working of Just in Time(JIT) Stock Replenishment:

  • It requires setting up a contract with a logistics provider(JIT) company to store and deliver equipment as and when needed.
  • An order will be made via an EDI (Electronic Data Interchange) system direct to the supplier.
  • Orders are captured by a bar code reading handheld terminal.

Tactics of Just In Time Stock Replenishment:

Following are the some tactics of JIT Stock Replenishment:

  • Use a pull system to move inventory
  • Reduce lot size
  • Reduce setup time
  • Develop JIT delivery systems with supplier
  • Deliver directly to the point of use
  • Perform-to-schedule
  • Reduce set up time
  • Use group technology.

Advantages of JIT Manufacturing:

There are several benefits of JIT inventory in Manufacturing and those are:

  • In JIT Manufacturing we can see the constant production rate.
  • In JIT Manufacturing there is less manpower needed.
  • It is based on “We make what we can sell” i.e. if the product is required in the next stage only then it will be produced so that the wastage is zero.
  • In the long term, we can see a low production rate, less time needed to manufacture a product, and more importantly, it establishes a good relationship between customers and manufacturers.

Disadvantages of JIT Manufacturing:

Although this is a very effective method of production however still there are some disadvantages of JIT Manufacturing:

  • As this system based on “We make what we can sell” that’s why when the stock of product is limited, the product can easily go out of stock.
  • For JIT manufacturing you have to understand the requirements of each customer and plan accordingly. Otherwise, you cannot deliver the product on time.
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