Single Minute Exchange of Die
Single-Minute Exchange of Die (SMED dt .: Tool change in the single-digit minute range) designated in connection with Quick Change Over (QCO to German fast setup ) a method to reduce the setup time of a production machine or production line. The term “tool change” is misleading here, as the time from the last good part of the old production lot to the first good part of the new production lot is meant and can be better described as “production change”. The difference is that it is not just the time it takes to change a tool that is decisive, but also things like the provision of the new material or the parameterization of the machine and the like; that is, the entire time that cannot be produced.
The aim of SMED is to reduce inventories by converting the machine to a new production process without disrupting the production flow. The final goal can be seen as achieved when a machine or a production line can be converted within a production cycle so that a one-piece flow or even better a mixed-model one-piece flow can be implemented even with the most varied of products can. In this case the stocks in the line are also zero.
The process was developed by Shigeo Shingō , who as an external consultant was significantly involved in the development of the Toyota Production System (TPS). Implementation: In several iterative steps, the set-up time is improved first through organizational and later through technical measures. To minimize costs, it is important that the steps are followed in the specified order. Experience has shown that each step leads to a reduction in setup time of 50 to 60% (compared to the previous step). This means that larger investments are only made at a very late stage, if at all.
SMED runs in four (five) steps:
- Separation of internal and external setup processes (organization)
- Transfer from internal to external setup processes
- Optimization and standardization of internal and external setup processes
- Elimination of adjustment processes
- (Parallelization of setup processes)
These steps are repeated until the set-up time is in the single-digit minute range, with each subsequent step usually leading to disproportionate investments in relation to the previous one.
An essential element in the implementation is to subdivide set-up processes into internal and possible external steps and to run through the external processes as long as the machine is still producing or is producing again.
- Internal steps can only be carried out when the machine is at a standstill (e.g. tool change).
- External steps can be carried out while the machine is still producing (e.g. provision of tools and preliminary products).
Various techniques are used for optimization, e.g. B .:
- Preparation of the production change
- Use of clamps instead of screws
- Sliding tables instead of cranes
- separate preheating
- Intermediate clamping devices for adjustment outside the machine
- Parallelization of setup processes - simultaneously instead of one after the other - d. H. Use several employees instead of one (is often seen as a fifth step)
- Elimination of adjustments
- mechanization
- Standardization of setup activities
- Standardization of tool dimensions
Further developments of the SMED process are:
- Zero changeover: changeover within three minutes
- OTED (= One Touch Exchange of Die): retrofitting with one arm movement
Effects of SMED on Employees
The employees of a company provide suggestions that lead to faster set-up processes as part of a group work session during working hours, ie ideas and thoughts of each individual are recorded on a flipchart, evaluated and feasible suggestions are then put into practice if necessary. In addition, many large companies have the company suggestion scheme (BVW), in which proposals submitted in writing are evaluated and realizable proposals are then put into practice if necessary. This can result in a bonus for the employee for his suggestion. If there is no regulation in the company for the evaluation of group suggestions from guided working groups (moderated workshops) or if the regulation prohibits the payment of bonuses in this case, the employee does not receive a direct financial reward for his suggestions. However, it may be the responsibility of the employee to make suggestions in the workshop or to submit them as a personal suggestion for improvement afterwards.
Whether employees endanger or safeguard their own workplace through their ideas for improvement depends, among other things. a. depends on the economic situation in which the company is. In companies with underutilization, savings in set-up times can be combined with savings in personnel in the short and medium term. In busy companies, in line production especially at their bottleneck systems, time savings can usually be converted into additional production and possibly lead to an increase in staff. In both cases, however, the company can increase its competitiveness in the long term through increased productivity and flexibility and thus secure jobs in its own company.
literature
- Blom Product Development Team: quick setup. On the way to lossless production with the Single Minute Exchange of Die (SMED). CETPM Publishing 2007, ISBN 978-3-940775-02-3 .
- Bert Teeuwen, Alexander Grombach: SMED The successful method for quick set-up and changeover . CETPM Publishing 2012, ISBN 978-3-940775-11-5 .
- Shigeo Shingo, Quick Changeover for Operators: SMED System. Productivity Press, 1996, ISBN 1-56327-125-7 .