... As far as our person is concerned, we retry every year a new diet. This brings us a transient success which makes us feel better, however experience has shown that in the long term we will not achieve very much. How much better it would be to change our eating habits non-transiently and to do more sport.
The same patterns of behavior can be found in production. Current problems are removed by applying spontaneous and often insufficiently and short-term efficient approach. Unfortunately it is often omitted to seek for sustainable solutions.
This is where "Lean Production" comes into play. Lean or streamlining signifies the elimination of waste alongside the entire value stream. The aim is to implement overall lean and simple processes. The Lean Production activities focus on an employee-supported and realization-oriented improvement organization (CIP - Continuous Improvement Process). When we are talking about lean processes or lean systems, we do not solely mean the deployed tools and methods but rather a philosophy of eliminating redundant workflows by an intelligent organization which must be learned, understood and lived. The detection and elimination of waste is an integral part of this philosophy. In this connection we should emphasize the term more intelligent organization. "Lean Production" does not simply mean to eliminate redundant work steps. In order to be able to establish a lean process or even an overall lean system in a production, we must possibly accept some waste for a short time respectively introduce new work steps to eliminate waste in the long run.
Surgeon compared with assemblers
In this connection the following example may be cited: Have in mind a surgeon and his nurse. The surgeon will only be able to work efficiently if the nurse hands him the required instruments and other utilities. This means that the surgeon is able to perform a value-generating work without the risk of distraction. And now imagine the surgeon would be obliged to seek his scalpel or the required swabs during the operation. Nobody would like to be patient of such a surgeon. Operation successful, patient ...
When applying this example to production, this means that some non-value generating preparations must be made in order to be able to work efficiently. In production the example of the surgeon corresponds to the preparation of the required material and tools at the workstation. The value-generating employee should not be obliged to procure the material by himself. As in the example of the surgeon it would make much more sense if this job would be performed by a logistician. Here you should ask yourself the following questions:
- How must the material be provided at the workstation?
- Are special cases / boxes required for the picking operation?
In this connection one talks of separating value creation and logistics. In other words, there are professionals for the logistic processes and professionals for the value generating processes. A worker in the assembly department should have his tool and only the required tool optimally available at his workstation. A toolbox contains normally nearly all the tool keys whether they are needed or not. Among the frequently used tool keys normally is not only one available. The consequence is that the worker has to look for the suitable tool key in his tool trolley which can be highly time-consuming. In order to reduce the unnecessary time spent on searches, the required tool should be easily accessible at a tool board and not be placed somewhere in a toolbox.
Another example is the reduction of batch sizes resulting in an improved value stream. This however necessitates that the machine / plant will have to be retooled perhaps several times. The results are of course additional set-up costs and increased real waste. By using the SMED method (Single Minute Exchange of Dies – Set-up in the single digit minute range) it is possible to reduce significantly the set-up work. The SMED method examines carefully particular work steps by observing the following criteria:
- Is it possible to eliminate this work step?
- Is it possible to combine this work step with another?
- Would it make sense to change the sequence of the set-up operation?
- Is it possible to simplify the work step?
In Germany this is called EKUV analysis (E=eliminate, K= combine, U= change, V=simplify). A setup workshop examines not only the above-mentioned criteria but also each activity related with internal and external setup work. Internal setup work means that the machine must be at a standstill during setup, e.g. when changing a drill / milling tool. External setup means that the work steps can be performed as a preparatory or follow-up operation, e.g. tool setting. The time saved can now be used for the reduction of batch sizes.
Spotting waste
As the Lean Production concerns always the reduction of waste, the following types of waste have been defined:
- Waste caused by overproduction
- Waste caused by waiting / idle times
- waste caused by unnecessary or too long transport routes
- Waste caused by organizational deficits in the work process
- Waste caused by excessive inventory
- Waste caused by unnecessary movements
- Waste caused by rejects and rework
- Waste caused by unemployed expertise of employees
Waste caused by overproduction is here the type of waste which initiates partly other types of
waste, or else conceals other types of waste. If a manufacturing step produces more than the downstream process is able to process, the result will be inevitably a storage bottleneck, i.e. a new type of waste will be initiated. But an overproduction may also conceal other types of waste. Naturally a repeated standstill of the machine is not noticed at once as there is sufficient material available. Quality problems too remain frequently undiscovered as defective parts may be replaced by parts from excess inventories.
In most cases problems are only uncovered when reducing waste, regardless the type of waste, and then the employees will be forced to solve the now apparent problems by employing their creativity.
The topic "Lean Production" has been treated in a great deal of literature which you may consult. Most of the readers will certainly say: "Our product range and our processes are completely different from the described examples in these books. This is no alternative for us!". But that is exactly the reality. It goes without saying that each production setup and each manufacturing process differ from each other and learning a "recipe" by heart to transfer it subsequently in one's own company, e.g. the implementation of a One-Piece-Flow assembly line or of a kanban system or a super / mini market, might actually make no sense. Therefore it is important to become first familiar with the underlying philosophy of "Lean Production" because each process contains worthless elements (waste). The used tools differ from company to company.
The major problem however is to be able to detect waste in the factory by ourselves or to sharpen our view in this respect. This you may compare with your visual faculty. Assuming you have a weak visual faculty, however you did not really notice it so far as the visual defect was not very strong so that you were not really adversely affected. By using various strong ophthalmic lenses at the optician, you realize what has escaped you so far. It was the optician who enabled a comparison and an assessment of the differences in acuity and helped you to recover an improved visual faculty. Your view was sharpened.
Sharpening the view against routine blindness
In companies this is called "routine blindness" which appears almost always after years in the same company. A routine blindness can normally only be detected and changed by impulses from the outside. This however necessitates the willingness of making investigations in the own company and be open for a change management. In economic difficult times which are ruled by a global market, it is of particular importance not to come to a standstill but to further develop and enhance efficiency in order to remain competitive in the long term.
Author: Dipl.-Ing. Andreas Schädle, SCHULER Business Solutions AG, published in the trade magazine "Holz- und Möbelindustrie 2010", Kuhn Verlag