The previous reply assumed that you would be using the 217Plus Software, which is the best tool to use as it incorporates the complete 217Plus method and all calculations, plus it includes the EPRD/NPDR database of parts.

If you plan to use the current spreadsheet version of 217Plus (the 217Plus Calculator) – be aware that it calculates only an assembly failure rate, and does not incorporate the 217Plus method’s use of ‘process grade factor’ or other features of 217Plus. But you could still include EPRD/NPRD data as follows:

Procure the EPRD/NPRD database (separate purchase).

Locate the desired part in the database, and record the failure rate.

Adjust the RIAC (NPRD/EPRD) failure rate according to the duty cycle of your application:

Failure Rate(217Plus) = Failure Rate(RIAC)*Duty Cycle.

Add the part’s adjusted failure rate to the failure rate in the 217Plus Calculator.

To complete the 217Plus analysis per the 217Plus method, you would then have to apply the Process Grade Factors through a separate calculations (outside of the 217Plus Calculator) that you would have to develop based upon the equations in the Handbook of 217Plus Reliability Models.

Since the Software version of 217Plus has the EPRD/NPRD database integrated into it, and supports the complete 217 methodology such as calculation and application of Process Grade Factors, support for multiple assemblies in a system, can store a library of component’s, has the ability to Import Bills of Materials, can generate reports, etc., I would recommend using the Software version of 217Plus over the present spread sheet version, as its a more complete, cost effective, and more work efficient solution.

One drawback to the software: it presently only runs on Windows XP. If you have Windows 7 Professional (or Windows 7 Enterprise), you could download “Virtual Machine” and “XP Mode” (free downloads from Microsoft) to set-up and XP environment on your Windows 7 system. (You cannot run XP mode on Windows 7 Home version)

The 217PLus Calculator is still a viable solution, with the caveats that it is more much more labor intensive to use than the Software solution, you would need to do extra work outside of the 217Plus Calculator in order to perform a complete 217Plus analysis.

Paul Wagner