Just-In-Time (JIT) Manufacturing

Introduction

Just-In-Time (JIT) Manufacturing is a philosophy rather than a technique. By eliminating all waste and seeking continuous improvement, it aims at creating manufacturing system that is response to the market needs.

The phase just in time is used to because this system operates with low WIP (Work-In­Process) inventory and often with very low finished goods inventory. Products are assembled just before they are sold, subassemblies are made just before they are assembled and components are made and fabricated just before subassemblies are made. This leads to lower WIP and reduced lead times. To achieve this organizations have to be excellent in other areas e.g. quality.

According to Voss, JIT is viewed as a “Production methodology which aims to improve overall productivity through elimination of waste and which leads to improved quality”. JIT provides an efficient production in an organization and delivery of only the necessary parts in the right quantity, at the right time and place while using the minimum facilities”.

1. Seven Wastes

Shiego Shingo, a Japanese JIT authority and engineer at the Toyota Motor Company identifies seven wastes as being the targets of continuous improvement in production process. By attending to these wastes, the improvement is achieved.

  1. Waste of over production eliminate by reducing set-up times, synchronizing quantities and timing between processes, layout problems. Make only what is needed now.
  2. Waste of waiting eliminate bottlenecks and balance uneven loads by flexible work force and equipment.
  3. Waste of transportation establish layouts and locations to make handling and transport unnecessary if possible. Minimise transportation and handling if not possible to eliminate.
  4. Waste of processing itself question regarding the reasons for existence of the product and then why each process is necessary.
  5. Waste of stocks reducing all other wastes reduces stocks.
  6. Waste of motion study for economy and consistency. Economy improves productivity and consistency improves quality. First improve the motions, then mechanise or automate otherwise. There is danger of automating the waste.
  7. Waste of making defective products develop the production process to prevent defects from being produced, so as to eliminate inspection. At each process, do not accept defects and makes no defects. Make the process fail-safe. A quantify process always yield quality product.

2. Benefits of JIT

The most significant benefit is to improve the responsiveness of the firm to the changes in the market place thus providing an advantage in competition. Following are the benefits of JIT:

  • Product cost—is greatly reduced due to reduction of manufacturing cycle time, reduction of waste and inventories and elimination of non-value added operation.
  • Quality—is improved because of continuous quality improvement programmes.
  • Design—Due to fast response to engineering change, alternative designs can be quickly brought on the shop floor.
  • Productivity improvement.
  • Higher production system flexibility.
  • Administrative and ease and simplicity.

Source: KumarAnil, Suresh N. (2009), Production and operations management, New Age International Pvt Ltd; 2nd Ed. edition.

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