Preventing problems before it is China’s ancient philosophical wisdom, from the self-speaking book “Easy to the economy”: “Gentlemen think and think about it.” Such wisdom is also considered by the three major American car companies Chrysler, GM, Ford, They have made this idea implemented in the automotive industry, and the PFEMA in the TS16949 quality system is the ultimate. However, how is the PFMEA system used? prototype shop
The FMEA is further divided into DFMEA and PFMEA, which are analysis techniques for the analysis technology and product realization process during product design and development. In reality, there is a very common situation, that is, the development of PFMEA has to wait until the output of DFMEA begins. This is either due to misunderstanding of FMEA or laziness.
Let me explain in detail the relationship between DFMEA and PFMEA. prototype shop
First of all, these two tools do not have a complete relationship. It is not the development of PFMEA that is not developed by DFMEA. The reason is that DFMEA and PFMEA target completely different objects. DFMEA is aimed at the product itself, mainly the structure, material selection and scheme risk of the product; and PFMEA is aimed at the risk of the production process. From the product realization process, although the product design is started earlier than the process design, the product design and process design are mostly parallel work, and the process design is not completed until the product design is over. Therefore, it is natural that DFMEA is not developed to develop PFMEA.
Secondly, although PFMEA does not have to wait until DFMEA is developed, it is not completely related to DFMEA. The choice of some processes, including equipment, tooling, working methods, detection methods and other process factors, is closely related to the design, so product design will affect the process design, PFMEA development is to take product design for granted. prototype shop
Third, control the transfer of content. Try to convert the content of the control in PFMEA to the control content of DFMEA. The reason for this is that the control method that can be solved from the product design is much easier and more stable than the process control. For example, common manual welding, in PFMEA, the factors to be controlled are the choice of solder wire, the choice of soldering iron tip, the temperature of the soldering iron should be stable, the method of dragging tin should be fixed, and the speed of dragging tin should be fixed. However, from the design point of view, as long as the Conector structure is chosen instead of the welded structure, the control of these manual welding is unnecessary, and it becomes the control of the SMT Conector, which is much easier. In DFMEA, you only need to control the choice of Conector.
Fourth, control the transfer of content from DFMEA to PFMEA. The general process of transfer is from PFMEA to DFMEA, but transfer from DFMEA to PFMEA is also very common. For example, the example of welding, from the perspective of sound quality, is transferred from PFMEA to DFMEA, but at a level acceptable for quality, when cost considerations are more, there may be a way to design and cancel the Conector and use welding. This has led to the transfer of control content from DFMEA to PFMEA. At this time, CFT should fully communicate and reach an agreement to clearly identify this risk and have sufficient control in the process. prototype shop
All in all, DFMEA and PFMEA are aimed at different risk targets and different scopes, but they have close interrelationships, they need to perform their own functions, and they must be organically combined. It is necessary to promote the transfer of PFMEA control content to DFMEA control content to improve stability. It is also necessary to accept the transfer of control content from DFMEA to PFMEA under certain conditions. The overall purpose is the same: to achieve quality goals, maximize revenue!
A quality person asks if there is a PFMEA experience introduction, and it is recommended that the quality predecessors do PEMEA. prototype shop
1. Prepare for work beforehand. To strengthen the statistical analysis of the data. Make an analysis of the failure data of a product similar to the product and sort the failures. These data are not only used for PFMEA, but also useful for development designers, so spend time on it and be absolutely worth the money.
2. About the team. We often say that it is important to do FMEA to pay attention to the CFT method. However, if you build an irresponsible or muddy team, it is not endlessly noisy, it is endless consumption, it is not as good as individual combat. . You can make a discussion board on the basis of individual soldiers, and everyone will discuss it again, which can improve work efficiency. prototype shop
3. About the score. It has been found that many companies (people) are not very rigorous in the scores of PFMEA. The same failure, the same failure effect, the scores before and after the difference can be a lot, visual confirmation to hit 3 or 4, the rigor is very simple to play, carefully follow the manual, but a few people are willing to turn from time to time Looking at the manual, it is a good idea to simplify the scoring table in the manual to your PFMEA form. This also reflects the idea of poka yoke. You can set each of the scored cells to the type of drop-down selection, and you can see the corresponding text description when selecting the number.
4, PFMEA can be distinguished by class. You don’t have to subdivide into every product. The premise is a homogeneous design. prototype shop
5. PFMEA is a dynamic file. From it, we can best see the shadow of continuous improvement. I have seen a lot of PFMEAs, either behind them, or writing “enhanced employee education”. The human factor should not be used as an improvement point. People’s skills can meet the requirements, which is a prerequisite for us to do anything. For example, if the leak assembly fails, you may analyze it because of “employee’s negligence.” If you write “enhance employee education” in your countermeasures, how to prevent leaking assembly and leaking assembly? Is the focus of your strategy.
6. Many people have been wondering what is the use of PFMEA? At the manufacturing site, it is based on the control plan. It is better to do a good control plan than to do a good job at PFMEA. prototype shop
The function of PFMEA is:
1) Warning designer, anti-micro-duration;
2) Warning process developers, prevention first;
3) alert the operator or operator to safety first;
4) Alert the author, the first brain.
The above is some of the experience of quality predecessors doing PFMEA, hoping to help the quality people with needs. prototype shop