A better way to drill holes for aircraft Wednesday, 18 January 2017

Airbus engineers have improved on the rivet hole drilling process, a common task in the manufacture of aerospace parts, in a bit to improve tool life and achieve more consistent results.

The creation of rivet holes, which are used to join different components using rivets, screws or bolts, is a key step in the production and assembly of airplanes and structural components, as well as other industries like automotive manufacturing. This process is performed manually or semi-automatically using drilling machines or drill feed units, and the holes are generated in large numbers, to precise tolerances.

Due to the rising need for new aircraft, manufacturers like Airbus are increasingly moving towards automated processes. But in the process, Airbus found that drilling operations are vulnerable to disruption, because the drilling process creates metal chips as the material is drilled away. The length of these chips means they can become stuck in the flutes of the drill bits, causing debris to be accumulated. The accumulation of these chips cause high rates of wear and tear on the tools, as well as damage to the work pieces and inconsistent hole diameters.

Airbus project manager Dr Sascha Fangmann's team worked on ways to resolve these issues and optimise the automated manufacturing process, introducing an electrical vibration spindle in an industrial robot.

Using this new vibration-assisted drilling technology, holes are drilled automatically, but the drill bit is moved in and out of the material several times per tool rotation with superimposed sinusoidal axial oscillations. The reduces the occurrence of chip jamming by facturing the chips before they can get too long.

By combining this technique with automation, the Airbus engineers can optimise the frequency of the oscillation in order to match the cutting parameters feed, amplitude and frequency, delivering the best quality in chip extraction.

According to Airbus, the new fully-automated electrical vibration drilling mechanism resulted in an up to 50 percent reduction in processing time for thick material packages with titanium. The engineering breakthrough also significantly reduced tooling wear and tear, concessions and burr formation around holes, reduced surface damage and cutting temperatures, especially in hard-to-cut titanium alloys.

Airbus will install the first demonstrator of the new technology at its facility in Bremen, Germany, in 2017, and expects by year end to be producing rivet holes in wing flaps for the A330s and A350 using a fully-automated articulated robot system with a magnetically-levitated drill spindle.