LEAN MANUFACTURING

Lean Manufacturing

Lean Manufacturing

Introduction

Ohno's Seven Wastes

Waste is one of the major causes that affect the profitability of any business. Waste is referred to all those elements that increase the cost without adding value to the product. Seven wastes were originated in Japan, and it is generally known as “Muda”. It was developed by Taiichi Ohno (Toyota's Chief Engineer). This tool was designed to eliminate the waste. Earlier it was known as the core advantage of “Toyota Production System”, but later on, it was named as a tool of “Lean Manufacturing”. It is significant to comprehend the need to realize what waste is, how it can be eliminated and where it exists, in order to enhance the quality and the overall performance. “The Seven Wastes” are:

Waste of Over Production

Waste of Inventory

Waste of Motion

Excessive Transportation

Inappropriate Processing

Waste of Defects

Waiting

Waste of Over Production

Over production or waste of over production, involve producing more than the market demand, producing soon (before its demand) or producing too much, both results in push strategy rather than pull.

Waste of Inventory

Inventories are considered “Muda” when they do not add value to the product. Work in process, parts, raw material and supplies are the forms of inventory.

Waste of Motion

The movement or mobility of inventory, product, and equipment that does not add value is a waste.

Excessive Transportation

The unnecessary use of pallet movers, trucks, forklifts and conveyers that adds no value is a waste.

Inappropriate Processing

The unnecessary manufacturing process such as inappropriate tools, methods and procedures that are performed on the product with no value is “Muda”.

Waste of Defects

The waste of defective products that includes the cost of testing or detection such as, scrap, returns, warranty claims, and rework is “Muda”.

Waiting

Queues, storage and idle time are known as “Muda”. For example if an operator is available and ready to proceed for the next process but he remains idle.

Examples

If we talk about Toyota and its manufacturing processes, then we should consider how Toyota managed their over production or underproduction and other wastes. Toyota had given the contract to Cadrex to manage their service parts inventories. This was done through monthly stock replenishment and forecasting the customer's demand for more than two months. At Toyota, the service parts stock was replenished weekly or bi-weekly. Thus, orders were processed during night batch to the warehouse but they were received in the day time. This causes huge fluctuations in stock and forecasted demands.

In the response of the fluctuation, Toyota chose the method of “buy one, sell one”. The method implies of daily scheduling of separate orders and cut-offs by the delivery route. Orders were picked, processed, packed and shipped on immediate basis right after the cut-offs. This results in replenishment of lead-time reduction and it also decreased the inventory supply by approximately 35 days (almost half of the total supply of inventory). This enhanced their delivery performance and supplier effectiveness/efficiency. This practice enables Toyota's ability to increase their productivity and cut their inventory.

Five- S's of Lean Manufacturing

Lean is defined as a system that develops a social and ...