Reliability Demonstration Testing (RDT)
A Reliability Demonstration Test (RDT) is the process of demonstrating the reliability of a product. RDT’s are usually performed at the system level and is typically set up as a success test.
A company that needs to understand the reliability of a product prior to shipping can use an RDT to determine this. Predictions are valuable early in a design cycle, but later in the design cycle, an RDT can give a much more accurate estimate of reliability.
An RDT will be able to approximate how long a product will last before it fails. We shall run the RDT in an accelerated manner so that we can find out this information before we start shipping the product.
VALUE TO YOUR ORGANIZATION
Reliability Demonstration Tests have tremendous value in many areas. They can:
- predict the life of the product in the field
- determine if the product is ready to ship
An example of Reliability Integration during a Reliability Demonstration Test is as follows:
HALT can help with an RDT
Two of the most important pieces of information to decide upon when planning an RDT is which stresses to apply and how much. From this, we can derive the acceleration factor for the test. HALT can help with both of these.
- HALT will identify the effects of each stress on the product to determine which are most applicable.
- HALT will identify the margins of the product with respect to each stress. This is critical so that the highest amount of stress is applied in the RDT to gain the most acceleration without applying too much, possibly causing non-relevant failures.
There are 3 stages to a Reliability Demonstration Test – Planning, Testing/Monitoring, and Final Analysis
In the planning stage, a reliability goal is established. Then, a reliability demonstration test model is chosen. We shall then develop a Decision Matrix and outline all of the parameters that we must decide on prior to writing the plan, including types of stresses, number of units, length of test, confidence, etc, along with advantages and disadvantages for each. From this matrix, we shall jointly decide on all of the parameters that will go into the RDT Plan.
Testing and Monitoring Stage
In the testing and monitoring stage, the Reliability Demonstration Test is performed and the results are monitored to determine status compared with the goal. The test shall be set up so that the monitoring will only need to be performed a few times a week, once a day at most.
Final Analysis Stage
In the final analysis stage, the data is compiled and a report is written on the results. The report will compare the achieved results to the goal and will show how the data was calculated. It will contain detailed information about the models used.
The following case studies and options provide example approaches. We shall tailor our approach to meet your specific situation.
RDT using Duty Cycle as an Accelerant
A Medical Device company estimated their duty cycle to be about 40%. As part of the RDT, we chose to use duty cycle as an accelerant by increasing this to 100%. This got us an acceleration factor of 2.5 to 1. Using this coupled with a 10 unit sample, we were able to demonstrate 5 years of reliability in about 6 months.
RDT using High Temperature as an Accelerant
A Power Supply manufacturer went through HALT and the high temperature limit was 100 Deg C. For the RDT, we backed off 25 Deg C and ran the supplies at 75 Deg C. We calculated the acceleration factor by plugging 75 Deg C into our Reliability Prediction as an end-use environment. The factor came out to be 5 to 1. Using this coupled with a 10 unit sample, we were able to demonstrate 5 years of reliability in about 3 months.
RDT using Temperature Cycling as an Accelerant
A manufacturer of Radio Frequency devices for the outdoor market determined that their product experiences one deep temperature cycle a day. For the Reliability Demonstration Test, we chose to accelerate this and run 12 cycles per day. Using this coupled with a 10 unit sample, we were able to demonstrate 5 years of reliability in about 1 month.