The phrase describes the process of extracting a fastener that has fractured, sheared, or otherwise become unserviceable while lodged within a threaded hole. This often involves specialized tools and techniques to avoid further damage to the surrounding material or threads. A typical scenario is encountering a corroded bolt head that snaps off during attempted removal, leaving the threaded shank embedded within the component.
Successfully completing this task is crucial for equipment maintenance and repair across various industries, from automotive and aerospace to manufacturing and construction. Avoiding the need to scrap or replace entire assemblies due to a single broken fastener saves significant time and resources. The development of effective extraction methods has evolved over time, with advancements in tool design and metallurgy enabling the removal of increasingly stubborn and challenging fasteners.