What is the Nature of Lean Manufacturing?
The concept of Lean Manufacturing is a continuation of the mass production system, known in the twenties as the ‘conveyor belt’ of automotive manufacturer Ford. Taiichi Ohno and Eiji Toyoda, two employees of the automotive manufacturer Toyota in Japan, developed the Toyota Production System (TPS) after the Second World War. The concept became known worldwide as ‘Lean Manufacturing’ thanks to the best seller “The machine that changed the world”, in which the aspects leading to the success of the Toyota production system are described.
In the eighties Lean Manufacturing got a basis in the US. This was partly caused by the co-operation between Toyota and General Motors, who build a factory together. It lasted until end of the eighties, beginning of the nineties before American companies also wanted to be so-called ‘Lean Manufacturers’.
What Does ‘Lean’ Mean?
Lean gives the idea of skinny or slim. The word skinny has a negative connotation for a lot of people. There can also be a positive interpretation: ‘free of burden, healthy, a lot of freedom of movement, muscles, etc.’ With this specific vision in mind, people went looking for techniques that would allow a production system to function faster, cheaper, and better. Lean Manufacturing is distinguished by: a minimum changeover time, Just-In-Time (JIT) production, KanBan systems, a minimum of supplies and last but not least a “zero waste” attitude with each employee.
The aim of Lean Manufacturing is to shorten the time between the moment that the client places an order and the moment of delivery by eliminating all losses from this chain.
This is accomplished by:
- Realization of minimal changeover times (SMED)
- One Piece Flow implementation
- Implementing pull production planning
- Small Group Activity improvement teams
- eliminating defects
- Establish client-supplier partnerships
Lean Manufacturing: Example of achievements
- Increase of productivity by 20% within 4 months
- Reduction of the time to market by 20% within 4 weeks
- Decrease in production in progress by 57% within 10 months
- Increase of delivery reliability from 35 to 95% within 5 months
- Decrease in stock by 18% within 6 months
Among other things, these parameters are documented with the aid of Value Stream Mapping, whereby the figures are registered in the so-called Current State, so that the so-called Future State can be visualized and be monitored as to whether the improvements are developing in the right direction.
Implementation of Lean Manufacturing
When implementing Lean Manufacturing we use a number of steps. Central to those steps is the fact that all changes have the aim to improve services to our clients. During the implementation process, it is important to know the demands and wishes that the customer has with regard to the product. It becomes possible then to document the value adding process for a product. Among other things, this can be done with the aid of a Value Stream Map. We strive to eliminate all losses from the present process chain. That actually implies that the flow of materials and information from the previous process into the next is without delay and intermediate storage. In order to achieve this, we definitely require a very reliable and effective production with a continuously high Overal Equipment Effectiveness (availability rate*, performance rate*, and quality rate*). This can be achieved by implementing Total Productive Maintenance. By having a reliable and effective production process, the time span between placing an order and delivery becomes considerably shorter. It is, therefore, no longer necessary to produce based on what one has in stock, and one can produce a quantity the customer wants and at the moment he wants it. This is also called the transition from Push to Pull production. The production process makes then another step in the direction of the ideal process.