For all calculation models, part type identification is the major factor affecting the failure rate. This is because the part type dictates the parameters to consider in the calculation. For example, the following table compares the parameters required for parts stress predictions by the MIL-HDBK-217 FN2 and Telcordia Issue 3 models for two parts. Each of the required parameters has a dramatic effect on the failure rate predicted for the part.

When selecting which model to use, you must consider the different part type supported by the models. Certain models may not support many of the part types used in your system. For example, MIL-HDBK-217 FN2 includes a failure rate model for a part category/subcategory of Miscellaneous/Laser, and Telcordia Issue 3 includes a failure rate model for a part category/subcategory of Miscellaneous/Battery; however, the reverse is not true. Comprehensive information about the parts supported by various models and the part parameters required by them appears in Part Parameters Required for Predictions.

One of the biggest advantages provided by Windchill Prediction is how it allows you to mix models. For example, mechanical parts from the Mechanical model (NSWC-98/LE1) can be mixed with electrical parts supported by other standards. The only exceptions to mixing models are the FIDES, IEC TR 62380, and RDF 2000 models. Due to their unique calculation methodologies, you cannot mix these models with other models or use them with calculation methods supplied by other models.