Low-Density Material Fastener for Pig-Tail Removal

The fastener shank is divided into multiple thread regions with different thread configurations. The first thread region has a first helical thread with specific pitch and depth, while the second thread region has a second helical thread with different pitch and depth characteristics. This segmentation allows different portions of the fastener to perform different functions: the first region cuts and evacuates material, while the second region provides secure engagement without excessive extrusion.

Different regions of the fastener shank are given different thread properties tailored to their specific functions. The first thread region has deeper threads and different pitch suitable for material evacuation, while the second thread region has shallower threads and different pitch suitable for secure engagement. This local differentiation of thread quality optimizes performance for each function while reducing overall material extrusion.

The holding function is segmented from the cutting/evacuation function by providing separate thread regions. The first thread region with deeper threads handles material evacuation, while the second thread region with appropriately sized threads provides holding strength. This prevents the need for uniformly deep threads along the entire fastener length, reducing overall extrusion while maintaining secure engagement.

The thread parameters (pitch, depth, angle) are changed between different regions of the fastener. The first thread region uses parameters optimized for cutting and evacuating low density material, while the second thread region uses parameters optimized for secure engagement. This parameter differentiation allows the fastener to achieve both material evacuation and strong holding without excessive extrusion.

The fastener head combines multiple functions: it provides the driving interface for installation and simultaneously acts as a counter-sink to capture and contain the extruded material pig-tail. By merging the driving interface function with the material containment function in a single integrated head structure, the design eliminates the need for separate manual removal steps while maintaining manufacturing simplicity.

The extruded material pig-tail, which is normally a harmful byproduct requiring removal, is converted into a beneficial element by designing the head as a counter-sink that captures and contains the extrusion. The harmful extruded material is redirected to serve as a seal or filler that locks the fastener in place and provides a finished appearance, eliminating the need for manual cleanup.