Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - HScan (Inspection Sensor and Evaluation Criteria for Assessing the Inner Surface Quality of Holes in CFRP Parts)

Teaser

This project aims at the development of a machine-vision-based inspection tool for the inspection of the inner surface of bores in CFRP material and at the definition of the related quality criteria.Drilling holes for fastening systems is a very common manufacturing process in...

Summary

This project aims at the development of a machine-vision-based inspection tool for the inspection of the inner surface of bores in CFRP material and at the definition of the related quality criteria.

Drilling holes for fastening systems is a very common manufacturing process in carbon fibre parts assembly. Currently quality of the bores is ensured “through the process”, which means that the drilling process is kept within very tight process tolerances and no NDT method exists to inspect the surface.

The objectives of HScan project are: 
Definition of criteria for assessing the quality of the inner surface of holes in relation to fastening systems.
Development of an inspection tool that is suitable for holes down to diameters of 3.2mm (1/8”) and construction of a sensor prototype based on the concept.
Experimental validation of the sensor prototype in an aeronautical production environment.

Our approach is to work with an endoscope equipped with illumination from different directions to highlight surface structures.

Work performed

Work on HScan project started directly after the kick-off meeting in January 2016, by conducting a literature review. First results and conclusions could already be discussed at a meeting at the Airbus site in St. Nazaire. This was also the starting point for work on industrial use cases. The consortium had opportunity to learn about the drilling process at Airbus at a site visit.
FACC provided a first test panel early in the project. Profactor inspected the panel with an endoscope, doing first tests, regarding illumination and occurrence as well as visibility of defects. While the chosen drilling parameters lead to some obvious defects, especially entry and exit delaminations, it was not possible to tell if all defects are visible in the endoscope images. FACC did cut open the next two test panels, to allow for a direct view of the drill hole walls. Profactor compiled two defect catalogues, by manually inspecting each drill hole and noting down defects found and surface quality. The visual appearance of defect types, had to be derived from examples in literature. No visual inspection of the inner hole walls is currently done and no expert based ground truth was available.
Comparison of endoscope and direct view macro images of defects on the cut open holes, led to the addition of an LED light source opposite from the lens. Without this, Profactor found, not all defects were clearly visible. Profactors sensor design is based on the endoscope, camera and illumination combination found in the lab experiments and the requirements from the use cases, mainly the weight and size limits and the fixture via the drilling templates used at Airbus and FACC.
Based on the defect catalogues and findings from papers, Profactor compiled the mathematical formulation of the inspection rating laid out in deliverable 2.1 “Definition of criteria for surface quality”.
Current work is focused on conducting the first mechanical test. Images of 140 drill hole samples (70 fabric and 70 UD), prepared by FACC, were taken with the HScan sensor. First results should be available soon. Machine learning is structured in two parts: finding defects and rating the general surface in the images and learning the weights using results from mechanical tests.
Project work is accompanied by dissemination activities and preparations for exploitation of the project results, see updated “Plan for Use and dissemination/exploitation of foreground.


Main results acived in M18 are:
Definition of Use Cases
Mathematical Formulation of Surface Criteria
Prototype of HScan Sensor

Final results

The HScan sensor prototype offers a nondestructive method for inspection of inner drill hole walls.
Inspection criteria for the CFRP Surface in relation to a rivet fastener were developed and will be further refined in a test phase.


The foreseen Impact is stressing productiveness and cost reductions for the European Aerospace industry by:
• Cost reduction by prolonged life time of drills
• Optimizing drilling procedures

Website & more info

More info: http://hscan.eu.