The design of a process should allow us to limit design costs while ensuring that upon receipt, this will be efficient.
Designing a new process is a complex and costly process. In collaboration with the supplier, this step should allow us to design a robust process to avoid surprises once in production.
1 – For each VA stage, define the concept
First step, we define all the tasks that the process will have to perform: assembly, machining… For each of these tasks, a concept of a technical solution is defined.
2 – Perform the CAD model
Depending on the different technical solutions chosen and the general lay-out of the Position, we will proceed to the design of the process. The just-in-time design requires taking into account the TPM data and using the SMED principles from the outset.
2.1 Using the TPM principles
From conception, maintenance must be involved in the project. They will bring their knowledge and constraints. For more details, see pillar 5 of the TPM : mastery of equipment design.
2.2 Using the principles of SMED
There too, from the conception phase, the learning of the principle of SMED are to be implemented. The series changes must be made as simple as possible for the staff. The bridles of the tools must be quick, ¼ type of manual lathe, and accessible. The ” adjustments ” and other set of parts must be done against the stops.
2.3 Design in accordance with the principles of robust design
G. Taguchi has developed all the techniques and principles of robust design. Based on a design that makes theproduct “insensitive” to different “noises”, the robust design will allow us to design a more reliable process and generate less variability.
3-Set the cadence
The equipment must be designed to allow you to follow the Takt Time. We’ll find ourselves in two cases:
- The machine cycle is adjustable: it will then be adjusted to the Takt Time.
- The cycle is fixed and higher than the Takt Time: The machine will then wait at each cycle to compensate for the difference.
4 – FMEA Process
Finally, the final step will be to achieve a FMEA Process to predict all types of failures possible in relation to our need. It is on the basis of these elements and plans that we will be able to build the specifications.
- Use the principles of Karakuri (see below)
- Set up the principle of Jidoka: Poka Yoké, automatic shutdown, ejectors of faults…
- Design respecting the Chaku Chaku
- Prefer small machines dedicated to lines rather than large machines capability at high speed.
- Maximum use of parts catalogues: sensors, motors…
- Thinking about recycling components or equipment already in stock
- be allowed to modify current machines
- In the project group, an operator is necessarily present
Karakuri is written in Japanese most often ら く り, but sometimes also 繰 り, 絡 繰,機巧, or機関. This means a gadget, a mechanism, a machine, a trick, a device or a device.
This concept was born in Japan with mechanical dolls, called Karakuri ningyo (ら く り 人形). These dolls are mentioned for the first time about 1500 years ago, but they were more popular about 200 years ago.
These dolls can be considered as the precursor of robots. One of the best known examples is the Tea doll (opposite). The weight of a bowl of tea placed on the tray made the doll move from a determined distance while moving the feet (fed by a coiled spring). After removing the bowl and drinking the tea, the empty bowl is placed on the tray, this new weight causing the doll to turn and return to its original position.
Applying this principle, Karakuri asks to design a process using maximum mechanical tricks: counterweights, Gravity…
We specify “mechanics” well. Indeed, with sensors, computers… These same actions would be possible but are more costly, more complex to implement and more complex to maintain.
Example of Karakuri
E. Burke, J. M. Kloeber, R. F. Deckro (2002)-Using and abusing Quality Function Deployment scores
S. H. Thomke (1998)-Managing experimentation in the design of product