A Brief History of Lean Manufacturing

The history of lean manufacturing can be traced back almost 100 years in some guises. Here is an overview.

In the English translation of his book ‘TPS – beyond large scale production’ Ohno (1988) describes how TPS evolved out of need, as the market place in post war Japan required small quantities of cars to be produced in many varieties. This was very different to the Ford principle of mass-producing the same Automobiles in large production runs.

Although TPS began in 1950, it was not until the 1973 oil crisis that other Japanese firms began to take notice, and since this time the system has been studied, copied and implemented across many industries.

Womack, Jones and Roos (1990) coined the phrase ‘Lean Manufacturing’ to describe TPS when they printed the results of a five-year study into the automotive industry in the book ‘The Machine That Changed The World’. This gives a pretty good insight into The History Of Lean Manufacturing

Even with the massive amount of research that has taken place into the Toyota Production System, fifty one years after it was born, Slack et al (2001, p481) still refer to Lean Manufacturing as a ‘radical departure from traditional operations practice’.

Ohno (1998) describes the most important objective of the TPS as increasing production efficiency through consistently and thoroughly eliminating waste.

Figure 1. indicates how TPS differs from traditional approaches to improve productivity through adding resources and illustrates the impact of waste elimination on production lead-time.

So what is waste?

Womack et al (2003) define waste as any activity that consumes resource but adds no value as specified by the customer.

In order for us to understand the waste within manufacturing activities Ohno (1988) broke waste up into 7 elements.

These elements are: Overproduction, Over-processing, Waiting, Transport, Inventory, Motion, and Defects and they are defined from the history of lean manufacturing below:

Overproduction -

Producing things ahead of demand

Waiting -

Inability to move to the next processing step

Transport -

Unnecessary movement of materials between processes

Over processing -

Inappropriate processing of parts, due to poor tool and or product design.

Inventory -

Storing more parts than the absolute minimum.

Movement -

Unnecessary movement of people during the course of their work.

Defects -

Production of defective parts

The Seven Wastes Commonly found in physical production (Womack and Jones 2003, pp 351 – 352)

Ohno (1988) describes the four key elements of a TPS as: Just-In-Time (JIT), Jidoka, Standardised Work and Kaizen.

The make up of each of these elements is covered below

In general terms the key elements of Lean Manufacturing work together to continually improve production processes. Put simply, waste elimination is accomplished through Just In Time and Jidoka, maintained through Standardised work, and improved through Kaizen.

Just In Time (JIT) -

Producing what is needed, when it is needed, in exactly the amount needed. (Using pull systems (Kanban), continuous flow processing, and synchronising the production speed)

Jidoka -

The ability of production to be stopped in the eventuality of a problem, either by the machines themselves or people. (Using ‘stop systems’, and error proofing).

Standardised work -

Standardise procedures concentrating on the most efficient human movements and work sequence for each process.

(Using synchronous production speeds, working sequence and standard in process stock) Kaizen Never ending job design through continuous improvement (Using a basis of standardised work).

In summary the principles from the history of lean Manufacturing are to reduce waste through the application of a number of process improvement tools.

Understanding the Application of Flow processing techniques

Flow production is based on the Just In Time methodologies that fall within a ‘Lean’ production system. Womack et al (2003) contend that the concept of making products flow is almost counterintuitive and difficult for many people to conceptualise let alone implement.

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