Realization of product reliability

Usually in a company, production is carried out first, and when production reaches a certain stage, quality control is considered. Finally, with the passage of time, the hidden problems of products are gradually exposed, and I realize the need for reliability control and consider the need for a reliability engineer. As a reliability engineer, how to carry out reliability work in this situation? Generally speaking, the implementation of reliability is divided into four steps: planning, reliability test, reliability improvement and reliability maintenance;

In fact, the most important, effective and fundamental step in reliability work is the fifth step besides the above four steps: reliability design; However, at present, more than 99% companies (except military enterprises) only stay in the first four steps in their reliability design, and have not carried out adequate reliability design. How to realize reliability design is not discussed here (you prawns should take this as the main goal in your future work).

Now, you are lucky enough to be a reliability engineer in a company, so all you have to do is the first four steps.

First, make a reliability work plan.

For most companies, reliability work is still in its infancy; A considerable number of companies are also very passive in reliability work. Some companies start reliability work when customers ask for reliable information and data, and some companies even start reliability work after products are returned. Many companies are still blank in the work of reliability. Although the company leaders began to consider reliability (otherwise you wouldn't be hired as a reliability engineer), most people in the company are still unfamiliar with reliability, so the initial planning stage is particularly important.

First of all, you are a reliability engineer recruited by the company, responsible for related reliability work.

Next, you need to publicize the importance of reliability work; Reliability work cannot be done by one person. Everyone in the company should understand the importance and necessity of reliability, especially the attention of senior leaders. Products with poor reliability can still be used, so they are easily overlooked by most people. In addition, it is difficult to see the effect of reliable work for half a year, and it is difficult to proceed smoothly without the attention of leaders. When appropriate, we can use comparative data (such as customer complaints about previous products/repair rate, customer complaints about reliable products/repair rate) to illustrate the importance of reliability. Then, write a reliability test plan; After introducing the importance of reliability, we can make some reliability testing schemes for the company's products. It is suggested that the reliability plan is divided into two parts. The first part is the reliability test scheme, including the test flow, sampling method, test method, result judgment and other specific contents. The second part is the goal of reliability work. This part, of course, is to write that you want to do the reliability work in the R&D stage during your work, and control the quality of the company's products and reduce the product cost through reliability design. For this tangible achievement, the plan must be written and signed by the leaders. The first part is to let the leader know that you can do a lot of practical things, and the second part is to let the leader know that you have great ambitions.

Finally, promote the reliability test plan; This is a key step, and its main purpose is to let employees know what to test for reliability, so as to improve reliability in a targeted manner; Through promotion and discussion, employees of the company can reach an agreement in more aspects and reduce the possibility of detours. You can discuss the reliability test with the production technology department and R&D department, conduct some training for the marketing department, production department and after-sales department, and invite "experts" from other companies to give some lectures when necessary. In short, let the whole company know that you are a reliability engineer, and the benefits of doing so will soon be realized by yourself. Remember: don't worry that what you say is too simple (even if someone knows more than you do, he won't know everything), don't worry that the training time is too short (the shorter the better, as long as it is longer than 10 minute), and don't be afraid (no one is perfect, otherwise your annual salary will exceed one million). You did it specially after being confirmed by the company leader.

Second, the implementation of reliability testing

After all the preparations are completed, the second step is to test the reliability of the product. Before starting the real test, there are still some preparations, such as whether there is any equipment for testing. Generally speaking, reliability testing is mainly divided into environmental testing and mechanical testing; To do environmental testing, at least a "temperature and humidity alternating box" is needed, and it is best to have a low-temperature refrigerator; Do a mechanical test When doing a test, you should at least have a "mechanical vibration table", and it is better to have a "mechanical impact table". Generally, small companies are not perfect in experimental equipment, so you need to build it yourself (from the temperature and humidity box to the vibrating table to the EMC laboratory ...). If the company has no equipment, it needs to buy a temperature and humidity box (the price is not high, and the utilization rate is not low), so it is unnecessary to use the mechanical vibrating table (the price is high, and the utilization rate is not high; Third-party testing can be paid). If before you come to the company, the company has done the reliability test piecemeal, and there may be some personnel and equipment, then when you do the reliability test, you should apply to include this part in your "door" and name it "reliability laboratory" or "reliability testing department". In fact, there may be only one incubator and one operator, but it doesn't matter.

Only "self-reliance" can develop. With the temperature and humidity box, you can start the test. Basic performance test; Before the reliability test, the basic performance of the product must be judged. Through the performance test, the products can be divided into three grades: first, good products, second, bad products, and third, bad products (between good products and bad products, accounting for about 20% of the standard). Good products can be tested for reliability, but bad products can't be tested for reliability, so it is necessary to analyze the bad products (some are caused by defects in the production process-this part can't be tested for reliability, and some are just random phenomena with slightly deviated parameters-this part can be tested for reliability). In addition to judging whether it can be used for testing, the most important thing is that it can also be used to compare the performance after reliability testing. Reliability testing; According to the test plan, the corresponding products are tested for vibration and high temperature. After each test, it is necessary to measure the basic performance of the product (some tests require measuring the basic performance during the test); Then the basic performance changes before and after the reliability test are compared and analyzed to determine the reliability test results. Attention during testing: When testing, let the equipment automatically record (preferably print) the test environment; It is best to measure the sample together with the person in charge of the phase of the sample after the test. Changes in testing; For many reasons, you need to modify some tests in your actual work. For example: ① Going far away to do vibration tests can "centralize" the vibration tests of various products; ② Some people think that the test time is too long (the reliability test may be around 1000 hrs), so you should consider speeding up the test (about: if the temperature rises 10℃, the product life will be halved; See the next section for details); ③ If the equipment controls temperature and humidity at the same time, it may be out of range at the initial stage of rising, so you can set the temperature before setting the humidity. ④ The temperature shock test may be realized by a high-temperature box, a low-temperature box and manpower (it will cost less than 300,000 yuan to buy a temperature shock box); ⑤ When it is necessary to bring humidity above 100℃, pressure cooker can be used (considering the accuracy of the test); Wait a minute.

No matter what changes, you should have detailed change records and test records; Everyone's experience and methods in practical work will not be less than mine. You will do better than me.

Third, reliability growth.

You can't just stay in the reliability testing stage. The essence of reliability work lies in reliability design. Only by doing a good job in reliability design/growth can we save costs and improve product quality. The improvement of reliability is mainly concentrated in the research and development stage and before finalization. Once the design is finalized or enters the mass production stage, it is impossible to improve the reliability of the design (too much waste and too high cost). However, most companies began to consider reliability because of the poor reliability of products and the requirements of the whole market (increased maintenance costs and increased returns), but the products have already been put into the market! At this time, it is impossible to raise the reliability of these products to a new height. What you can do is to look at repair rate High, but you must do a good job in the reliability of the next product. I suggest you focus on a product first to make it reliable. How to increase reliability? First of all, we must master the production process and technology, and fully understand the operation methods of each process. There is no need to explain this, it must be done.

In fact, to learn a certain technology, you should at least master the working principle of the company's products. Although you are not from the R&D department, you are responsible for the reliability of R&D products. You don't know the corresponding technology at all, so it is difficult to carry out your work. If it is a component product, you should know each raw material and its characteristics. If it is a system product, you should know something about hardware, software and structure, such as the function of each module, the interface between modules, the function of software and so on.

Then, set up a team (give her a good name) to be responsible for reliability growth. The more members, the better, but at least one should be included: company leaders, reliability engineers, R&D engineers, production technology and logistics personnel. I won't say much about the strength and necessity of the team here. Finally, improve the action; When there are defects in the testing process, it is necessary to analyze and improve the defects and standardize the improvement measures to ensure the quality is improved. The most commonly used method is "test-improve-test", which is repeated and improved step by step. It should be emphasized that every improvement should be dealt with seriously and thoroughly, and the case should be closed with data. Like ISO9000, improvement usually includes the following steps.

1. Reliability test; Sampling for testing according to the testing plan;

2. Description of the phenomenon; This part should describe the undesirable phenomena in as much detail as possible, including the product name (software and hardware version number), time and place of occurrence, so as to "record all product-related situations in chronological order";

3. Cause analysis; The analysis of the reason should get to the bottom of the matter and find out the root of the problem, rather than switching between phenomena, so that "when this reason is artificially generated, the phenomenon can be completely reproduced";

4. Improve actions; According to the analyzed reasons, take corresponding measures. At this time, we should consider two aspects: first, whether there will be such problems in other existing products and how to improve them; First, how to prevent such problems in subsequent products;

5. Effect confirmation; Mainly confirm two points: first, whether the improvement action is implemented; First, whether there will be such problems in the products after the implementation of the improvement action (there is data to prove).

6. Formal standard; If it is confirmed that the improvement measures are effective (reducing the defective rate), these measures should be written into the operation specification to guide the subsequent production. Also consider whether this measure is effective for other similar products;

7. resampling and retesting.

After many times of such "test-improvement-test", the defects of products will be less and less, and the quality will be better and better. Finally, when testing the reliability of the sample, no defects appeared.

Fourth, reliability maintenance.

Reliability maintenance mainly refers to maintaining the reliability of products in the best state when mass production is carried out; What is more difficult to do is to "keep it in the best state stably", and it takes a lot of efforts to do this.

1. supplier

In order to ensure that the raw materials provided by suppliers are stable in the best state, we can control them in four steps:

1. Carefully select suppliers to ensure that they meet the "Qualified Supplier Qualification";

2. In the process of supply, IQC inspection and reliability inspection shall be strictly implemented;

3. All process information is shared; Problems and anomalies in the inspection process should be notified to the supplier for improvement at the first time, and the case can only be closed if the improvement effect is proved to be good through various channels;

4. Feedback the quality status to suppliers regularly, and hold meetings to discuss when necessary.

2. Production process

Production is a process with the most "variables", and mechanization and automation are the most effective factors to ensure stability; Without complete automation, the production process mainly has the following control points:

1. Check whether the materials put into use are in good condition;

2. Check whether the operation of each station meets the operation requirements;

3. Check whether the output of each station meets the requirements of the next station;

4. Check whether the product performance meets the requirements of finished products;

5. Check whether the product reliability meets the specified requirements;

test

Conduct various tests on the company's products. In the process of testing, any problems need to be improved to improve product quality. The emergence of any problems is to point out a way forward for us; The improvement of the problem marks that the quality has risen to a higher level. With this attitude, nothing is impossible.