Is your machine a candidate for IRI rebuild? Rebuild candidates are typically 8 to 10 years old and have 20,000 to 25,000 or more hours of production time. When your machine is producing parts that no longer meet tolerance, it’s time for a rebuild. When up-time on the machine is less than what the product schedule allows, it’s time for a rebuild. When maintenance personnel are spending more time on the machine than the operator, it’s time for a rebuild.