Preventing troubles is the ancient Chinese philosophical wisdom. It comes from the language book “Easy and Economic”: “The gentleman is prepared for the sake of thinking and prevention.” Such wisdom is also taken into consideration by the three major car companies: Chrysler, GM, and Ford. They have allowed this idea to be implemented in the automotive industry, of which PFEMA in the TS16949 quality system can be used to the extreme. However, how exactly is the PFMEA system used? online CNC machining
FMEA is further divided into DFMEA and PFMEA, which are analysis technologies for product design, development, and product realization processes. In reality, it is common to see that the development of the PFMEA does not begin until the output of the DFMEA begins, either because of misunderstandings of the FMEA or because of laziness.
Today we will first explain in detail the relationship between DFMEA and PFMEA. online CNC machining
First of all, the two tools are not completely sequential, and it is by no means the development of PFMEA before the development of DFMEA. The reason is that the objects targeted by DFMEA and PFMEA are completely different. DFMEA is aimed at the product itself, which is mainly the product’s structure, material selection, and program risks; and PFMEA is aimed at the risk of the production process. From the product realization process, although product design is started earlier than the process design, product design and process design are mostly parallel work. It is not the end of the product design that is designed to start the process. As a result, DFMEA naturally does not need to be developed before PFMEA development.
Second, although PFMEA does not have to wait until the DFMEA is developed, it is not completely affiliated with DFMEA. The selection of some processes, including process factors such as equipment, tooling, work methods, and detection methods, is very much related to the design, so product design will affect the process design. PFMEA development is a matter of course considering product design. online CNC machining
Third, control the transfer of content. As far as possible, the content of the PFMEA control is converted to the DFMEA control content. The reason for this is that the control method that can generally be solved from the product design is easier to solve than the process control, and it is also much more robust. For example, common manual welding, in the PFMEA, the factors to be controlled are the choice of solder wire, the choice of the soldering iron head, the temperature of the soldering iron should be kept stable, the dragging method should be fixed, and the speed of dragging tin should be uniform. But from the design point of view, as long as the Conector structure is selected instead of the welded structure, these manual welding controls are unnecessary, and instead become SMT Conector’s control, which is much easier. DFMEA only needs to control Conector’s choice. online CNC machining
Fourth, control the transfer of content from DFMEA to PFMEA. The general process of transfer is from PFMEA to DFMEA, but it is also common to transfer from DFMEA to PFMEA. Also for example, the welding example, from a sound quality point of view, is transferred from PFMEA to DFMEA, but at the acceptable level of quality, when the cost is considered more, there may be a way to design the cancellation of Conector instead of welding. This has caused a shift in control content from DFMEA to PFMEA. This time, it is necessary for CFT to fully communicate and reach consensus, identify this risk clearly, and have full control in the process.
All in all, DFMEA and PFMEA have different target risks and different scopes, but they have close interrelationships and need to perform their own tasks. They must also be organically integrated. They must strive to promote the transfer of PFMEA control content to DFMEA control content to enhance stability. It is also necessary to accept the transfer of control content from DFMEA to PFMEA under certain conditions. The overall goal is the same: achieve quality goals and maximize profits! online CNC machining
Some quality people asked whether there was experience in introducing PFMEA. The recommendation for everyone was the experience of PEMEA.
1. Prepare beforehand. To strengthen statistical analysis of data. An analysis of the failure data of products similar to this product ranks these failures. This data is not only used to find PFMEA, but also useful for developers and designers. Therefore, spending time on it is definitely worth the money.
2, on the team. We often say that it is important to do FMEA to pay attention to the CFT method. However, if an irresponsible or sloppy team is formed, it is not an endless quarrel or an endless consumption. It is not as good as a single soldier. . A discussion version can be made on the basis of the individual soldier. Everybody can use it for discussion, which can improve work efficiency. online CNC machining
3, on the score. It is found that many companies (people) are not very strict on the PFMEA score. The same failure, the same failure effect, before and after the score can be a lot of difference, visual confirmation hit 3 or 4, the rigorous to fight is very simple, careful comparison of the next manual on it, but it seems that very few people are willing to turn from time to time If you look at the manual, then simplifying the score sheet on the manual to your PFMEA form is a good way to go. This also reflects poka yoke’s thoughts. Each scoring cell can be set to a drop-down selection type, and the corresponding text description can be seen when the number is selected.
4, PFMEA can be divided into categories. It is not necessary to subdivide each product. The premise is a homogeneous design.
5, PFMEA is a dynamic document. From it, we can best see the shadow of continuous improvement. After reading many PFMEAs, either they are empty or they write “Strengthening employee education.” The human factor should not be used as a point of improvement. People’s skills can meet the requirements. It is a prerequisite for us to do anything. For example, if the leakage assembly fails, you may analyze it because of “employee’s omission”. At this time, if you write “strengthening employee education” in your countermeasures is not appropriate, how to prevent the leakage of the assembly and how to check out after assembly? , is the focus of your policy. online CNC machining
6. Many people have been wondering what is the use of PFMEA? The manufacturing site is based on the control plan. It is not as good as a PFMEA to do a good control plan.
The function of PFMEA lies in:
1) Alert designers, prevent duplication;
2) alert process developers, prevention first;
3) Warning operator or operator, safety first;
4) Warning authors, brains first.
The above are some of the experiences of quality predecessors doing PFMEA and hope to help people with the quality they need. online CNC machining