Measurement of Hole Depth During Automated Drilling

ABSTRACT: Objective: Develop a method for measuring the depth of holes drilled through stacks of material with minimal impact to the drilling process to replace manual grip measurements. Description: Variability in the manufacturing process of aircraft skins and understructure components results in slight uncertainty in the thickness of material stacks. This uncertainty requires each hole across the outer surface of an aircraft to be accurately measured so that fasteners may be sized appropriately to reduce waste, excess waste, and ensure a tight fit. The current measurement process is manual and labor intensive. Mechanics use hand-operated thickness gauges, or grip gauges, to take measurements of holes individually. The measurements are stored electronically and used in selecting appropriate grip lengths for fasteners during kitting. Phase I will result in a prototype system demonstrating the ability to autonomously measure holes in a bench top environment, and that it saves time over the current process. Tests for accuracy and consistency will be performed. A preliminary cost estimate along with manufacturing/transition planning will be performed. Details of a plan to integrate the system into the assembly line will be provided. BENEFIT: The goal of this program is to eliminate the use of hand-operated gauges and manual labor for acquiring grip length measurements. Significant time savings can be realized by automating the measurement process. Ideally, the automated process would be integrated into the computer numeric controlled (CNC) machines that drill each of the holes and would occur in parallel with the drilling operation, thereby eliminating manual grip measurement and adding no additional time to the manufacturing process. If an alternate solution is pursued, it should still be able to decrease significantly the time required to take these measurements over the current manual process.