MTBF certification refers to the certification of the mean time between failures of a product. The English name is "Mean Time Between Failure". In fact, MTBF refers to the MTBF test report, which is a report on product reliability prediction. MTBF is a measure of the reliability of a product (especially an electrical product). The unit is "hour". It reflects the time quality of the product, and it is a capability that reflects the product's ability to remain functional for a specified period of time. Specifically, it refers to the average working time between two adjacent failures, also known as the average failure interval. In a nutshell, less product failure is high reliability. The ratio of the total number of product failures to the total number of life units is called "Failure rate". It applies only to serviceable products. It also stipulates that the ratio of the cumulative working time of the product to the number of failures during the total use phase is MTBF. Disk array products generally have MTBF of not less than 50,000 hours.
MTBF data calculation
Assuming that the MTBF of a computer is 30,000 hours, is it possible to detect this computer running continuously for 30,000 hours? Of course not, otherwise there are so many products that will not be tested for decades. The calculation method of the MTBF value. At present, the most commonly used authoritative standard is MIL-HDBK-217 (proposed by the US Department of Defense Reliability Analysis Center and Rome Laboratory and become an industry standard, which is used exclusively for military products), GJB / Z299B (Chinese military Standard) and Bellcore (AT & T Bell Laboratories proposed and became the industry standard for MTBF for civilian products).
The main consideration in the MTBF calculation is the failure rate of each component in the product. But because the failure rate of the device will be very different under different environments and different conditions of use, these factors must be considered when calculating the reliability index. These factors can hardly be calculated manually, but with software such as MTBFcal and its huge parameter database, MTBF values can be easily obtained. If a factory that works three shifts per day requires continuous operation for 24 hours and a failure-free rate P (t) = 99% or more, the MTBF of the machine tool must be greater than 4500 hours. MTBF 5000 hours requires higher and more complex production lines composed of different numbers of CNC machine tools. We only discuss a single machine here:
If the failure rate ratio between the host and the CNC system is 10: 1 (the reliability of the CNC system is an order of magnitude higher than that of the host), the MTBF of the CNC system must be greater than 50,000 hours, and the CNC device, spindle and drive parts, etc. The MTBF of the main part must be greater than 100,000 hours.
MTBF is not detected in actual operation, it is converted by the national standard detection algorithm. For example, Lenovo Yangtian ’s 60,000-hour MTBF is obtained by submitting 192 Lenovo Yangtian computers for inspection. During a 40-day experiment cycle, the voltage, temperature, and humidity of the test product are applied at a specific frequency. According to the corresponding relationship between the reliability and time characteristics of electronic products, the experimental results are converted using standard data models. Similarly, Tongfang ’s 100,000-hour MTBF exceeding the E350 was converted by 400 computers through 18-day inspection results.
In fact, we don't need to pay attention to how the MTBF value is calculated, as long as we know that choosing a product with a high MTBF value will bring us higher competitiveness. Of course, it is not that the higher the MTBF value, the better, the higher the reliability, and the higher the cost of the machine tool. Choose a moderately reliable according to the actual needs.
The purpose of MTBF analysis
MTBF usually corresponds to the following reference standards:
Telcordia SR 232
U.S. Military Standard MIL-HDBK-217
National military standard GJB / Z 299B