Infant Mortality Failure Period
In its early life, an item population exhibits a high failure rate, due mainly to manufacturing weaknesses, including:
• Poor joints and connections.
• Damaged components.
• Chemical impurities.
• Dirt and contamination.
• Assembly errors.
The failure rate decreases rapidly during the early life period and, at time t1 say, stabilises at a certain value.
Normally, the quality weaknesses are revealed soon after the item is put to use. Therefore, as part of the quality control process, it is increasingly common for stress screening tests to be used to eliminate these weaknesses by simulating in the factory a period t1 of use. However, stress screening is not always universally applied, and early life failures can cause problems in prediction because prediction generally claims to apply only to the useful life failure period.