What are the most important criteria for choosing a good product?

If you were driving a recently purchased car and were surprised to find that the brakes weren't responding, and you managed to stop the car, and at the mechanic's office you were told that repairing the brakes would take 3 hours, but after two days the same problem occurred again!

If you were the manager of an organization, and during peak hours, one of its main systems, installed just a few weeks ago, failed, and you were told that repairing it would take 72 hours, and after it was repaired the same problem occurred again!

What would you do, and how can you make a purchasing decision that avoids such situations?

Aside from planned obsolescence, any purchase is a type of investment that should yield some benefit or increase the profits of the company owning the project. Therefore, to ensure this benefit is achieved, there are factors that must be checked during the selection process. Among the most important of these factors are:

1- Mean Time to Failure (MTTF):

This is commonly referred to as the product or device's lifespan and is a crucial measure of the reliability of the systems or components used in manufacturing the device, including those that are irreparable (e.g., the LED chip's lifetime). The average product lifespan can be calculated as follows:

Take three identical devices and, after continuous operation, the first will fail after 15,000 hours, the second after 10,000 hours, and the third after 20,000 hours. The MTTF in this case will be: (15,000 + 10,000 + 20,000) = 45,000 hours. Divide the result by the number of samples, which is 3, so the MTTF = 45,000 / 3 = 15,000 hours.

This leads us to conclude that to prevent malfunctions, this component should be replaced on average every 15,000 hours. To avoid any potential failure, it should be replaced less frequently than 10,000 hours.

2- Mean Time to Repair (MTTR):

This refers to the time required to repair a system and restore it to full functionality. The MTTR begins at the start of the repair cycle and continues until the repair is complete. It includes the repair period, testing, and return to normal operating status. To calculate the MTTR, divide the total maintenance time by the total number of maintenance procedures performed in a given period. For example, imagine a device that failed four times in a year, and the total time required to repair the four failures was 8 hours. In this case, the MTTR would be 8 hours divided by 4 = 60 minutes.

3- Mean Time Between Failures (MTBF):

Frequent and frequent failures often lead to decreased customer satisfaction, not to mention financial risks and losses. Therefore, MTBF is a crucial metric in reliability engineering and has roots in many industries. For example, the failure of some medical devices or aviation systems can result in fatalities, and the failure of a queue management system can lead to arguments and problems. Thus, successful purchasing decisions are significantly influenced by the MTBF metric, which serves as a foundation for reliability.

MTBF can be calculated by determining the average reliability function R(t), which can be expressed as the expected value of the density function f(t).

More simply, it can be calculated using the equation shown in the image by subtracting the failure time from the operating time and dividing the result by the number of failures.

4- Mean Downtime (MDT):

The mean downtime can be defined as follows:

At Q-Linker Smart Solutions, we assure our partners that, in addition to our high standards, we consider the three factors mentioned above (MTTF, MTTR, MTBF). We select the highest quality components for long lifespans and prioritize ease of maintenance, making it as quick and simple as possible. We also provide original spare parts to maximize the MTBF.

Faisal Otari, Q-Linker Smart Solutions