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UPSC MainsMANAGEMENT-PAPER-II201310 Marks
Q9.

In Just In Time (JIT) manufacturing system, how does the 'subsequent process' signal the 'preceding process' to produce the quantity required?

How to Approach

This question requires a detailed explanation of the signaling mechanism within a Just-In-Time (JIT) manufacturing system. The answer should focus on the 'Kanban' system as the primary method of signaling. It should explain how demand at the subsequent process triggers production at the preceding process, avoiding overproduction and minimizing inventory. Structure the answer by first defining JIT and Kanban, then detailing the signaling process, and finally, illustrating with examples.

Model Answer

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Introduction

Just-In-Time (JIT) manufacturing, pioneered by Toyota in the 1970s, is an inventory management system aiming to align raw material orders directly with production schedules. This minimizes inventory costs and waste. A core component of JIT is the ‘Kanban’ system, a visual signaling system that controls the flow of materials. The fundamental principle is that nothing is made until it is needed, and the subsequent process ‘pulls’ production from the preceding process, rather than the preceding process ‘pushing’ materials onto the subsequent process. This question asks how this ‘pull’ mechanism operates, specifically how the subsequent process signals the preceding process to produce only what is required.

The Kanban System: A Visual Signaling Mechanism

The Kanban system is the primary method by which the subsequent process signals the preceding process in a JIT manufacturing system. ‘Kanban’ is a Japanese word meaning ‘signal’ or ‘card’. These signals can take various forms, but are most commonly physical cards, containers, or even electronic signals in modern implementations.

How the Signaling Works: The ‘Pull’ System

The process unfolds as follows:

  • Demand Trigger: When the subsequent process consumes a part or material, it creates a demand signal.
  • Kanban Release: This demand signal is represented by a Kanban. For example, when a workstation completes assembling a product and needs more of a specific component, it releases a Kanban card.
  • Kanban Transmission: The Kanban card is sent back to the preceding process – the one responsible for producing that component.
  • Production Authorization: The preceding process receives the Kanban card. This card *authorizes* the production of one unit of that component. Crucially, no production happens without a Kanban.
  • Kanban Return: Once the component is produced, it is sent to the subsequent process *along with* the Kanban card.
  • Cycle Repetition: The subsequent process receives the component and uses it in its production process. When it needs another component, the cycle repeats.

Types of Kanban Systems

There are several types of Kanban systems, each suited to different production environments:

  • Single Card Kanban: A single card authorizes both production and movement of materials.
  • Dual Card Kanban: Separate cards are used for production authorization and material movement, offering more control.
  • Withdrawal Kanban: Signals the movement of materials from one workstation to another.
  • Production Kanban: Signals the production of materials at a specific workstation.

Benefits of the Kanban Signaling System

  • Reduced Inventory: Production is only triggered by actual demand, minimizing work-in-progress (WIP) and finished goods inventory.
  • Improved Quality: Problems are quickly identified as they disrupt the flow of Kanban cards.
  • Increased Efficiency: Streamlined production process with minimal waste.
  • Enhanced Flexibility: The system can adapt to changes in demand more easily.

Example: Automobile Manufacturing

Consider an automobile assembly line. When the chassis assembly station uses a set of tires, it sends a Kanban card back to the tire manufacturing station. This card authorizes the production of one set of tires. The tire station produces the tires, attaches the Kanban card to the set, and sends them to the chassis assembly station. This ensures that tires are only produced when needed, preventing a buildup of excess inventory.

Limitations

While effective, Kanban systems require:

  • Reliable Suppliers: Dependable supply of raw materials is crucial.
  • Stable Demand: Significant fluctuations in demand can disrupt the system.
  • Disciplined Implementation: Strict adherence to the Kanban rules is essential.

Conclusion

In conclusion, the ‘subsequent process’ signals the ‘preceding process’ in a JIT system through the Kanban system, a visual and responsive mechanism. By ‘pulling’ production based on actual demand, Kanban minimizes inventory, improves quality, and enhances efficiency. Successful implementation requires a disciplined approach and a reliable supply chain. Modern JIT systems often integrate electronic Kanban systems for greater visibility and control, but the underlying principle of demand-driven production remains the same.

Answer Length

This is a comprehensive model answer for learning purposes and may exceed the word limit. In the exam, always adhere to the prescribed word count.

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Additional Resources

Key Definitions

Just-In-Time (JIT)
An inventory management system aiming to minimize inventory costs and waste by aligning raw material orders directly with production schedules.
Kanban
A Japanese term meaning ‘signal’ or ‘card’, used in JIT manufacturing as a visual signaling system to control the flow of materials and authorize production.

Key Statistics

Toyota, the pioneer of JIT, reduced its inventory turnover ratio from 12 days in 1975 to 4 days in 1985 after implementing JIT and Kanban systems.

Source: Toyota Motor Corporation Annual Reports (Knowledge Cutoff: 2023)

Companies implementing JIT systems have reported an average reduction of 30-50% in inventory costs.

Source: APICS (Association for Supply Chain Management) research (Knowledge Cutoff: 2023)

Examples

Dell’s Direct Sales Model

Dell’s early success was partly attributed to a JIT-inspired build-to-order model. Customers configured their computers online, and Dell only began assembling the computer *after* receiving the order, minimizing finished goods inventory.

Zara’s Fast Fashion

Zara utilizes a JIT approach to fashion. They produce small batches of clothing, quickly respond to changing trends, and minimize inventory by rapidly replenishing popular items and discontinuing unpopular ones.

Frequently Asked Questions

▶What happens if a Kanban card is lost?

A lost Kanban card disrupts the flow. Procedures are in place to investigate the loss and issue a replacement card, often requiring a temporary halt in production to avoid overproduction.

▶Can JIT be applied to service industries?

Yes, the principles of JIT can be adapted to service industries. For example, a restaurant can use a ‘pull’ system where dishes are only prepared when an order is received, minimizing food waste and ensuring freshness.

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