Project Description


Automated hole depth measurement system

After wing assembly, structures are mated in aircraft production processes and the fixture is brought to a CNC wing drill platform where hundreds of holes are drilled to attach the two substrates. Manufacturing process variability results in slight uncertainty in the thickness of material stacks of aircraft skins and wing understructure components. This uncertainty creates a requirement to measure each hole drilled in the wing assembly to ensure that appropriately sized fasteners will be used. The total part thickness, or fastener grip length, must be measured to reduce weight from oversized fasteners, reduce excess waste, and ensure proper fit. Currently this process is very time consuming due to manual measurements taken in every fastener hole.

  • SMRC’s GripChek software technology takes CNC drilling data and calculates hole depth (corresponding to fastener grip length) for every hole in real-time. For the first time, grip length measurement is concurrent with the drilling process.

  • GripChek software works by monitoring the CNC control process, particularly spindle torque and position. By correlating torque changes with features of the drilling process the grip length is measured precisely.

  • Precision grip length data is uploaded to the server, or digital thread, generating accurate fastener kitting information for each part and eliminating untimely and potentially costly errors in the fastener installation process. As-manufactured part measurements can be used to identify consistently out-of-tolerance parts and improve production processes.

  • SMRC is currently developing the GripChek system as a hardware and software solution that plugs into an automated drilling system for grip length determination.