Cutting tool lubrication upgrade speeds assembly

A Bielomatik system delivers lubrication through a spotfacing cutting and countersinking tool on the A380 Airbus assembly line – improving performance and optimising tool life and cycle times.

Using the Bielomatik MQL (Minimal Quantity Lubrication) two-channel system has prepared for more efficient automated manufacture of wing panels for the A380 Airbus at Broughton, UK Components now pass through various drilling, counter sinking and riveting operations without leaving any tool cutting lubricant residue.

It has proven to be a major advance over the previous lubrication operation that was messy, requiring the wings to be cleaned down after drilling and countersinking, said Bielomatik.

A high speed valve in Bielomatik’s MQL system enables oil deliveries to be as low as 3-5ml/h.

So that whilst the drilling, countersinking and spot facing operations are lubricated, the lubricant used is totally lost.

The metal chips are dry and fall away from the component surface more readily.

It is very beneficial on the Airbus wing assembly line where no oil can be allowed to remain in a drilled hole before riveting.

Assembling a single Airbus A380 wing has a span of 261ft (71.3m) involves precisely positioning a massive structure to drill, rivet, and bolt approximately 180,000 holes.

The operation presented a significant challenge for Airbus’s manufacturing team in Broughton and Electroimpact, USA.

Electroimpact is the prime contractor for wing-assembly automation tools.

Using a high level of automation, the Broughton plant is producing four pairs of wings a month.

The company said it has the largest and most productive wing-assembly plant in the industry.

The wing structures are a framework of spars and ribs covered with metal panels.

Each panel has a curved, aluminium alloy skin reinforced by stringers that ensure shape and strength.

Each wing surface consists of five panel assemblies, which include a total of 20 panels.

* Wing assembly – the Electroimpact assembly process is a two stage operation.

Initially four lines of fixtures are used for build-up of the upper and lower wing panels.

The lines use a highly automated process in which riveting- bolting machines traverse the panels attaching stringers to the skin.

Once the stringers have been attached to the wing sections, special purpose machine tools drill, countersink, rivet the sub-assemblies together then spot face the rivet head flush to the outer surface in one continuous process.

For the lower wing, holes as large as 1.25in (31.8mm) diameter are drilled for bolting the lower wing skins to undercarriage reinforcements.

* Tool lubrication – the original machine tool lubrication system comprised of an air feed, drawing oil from a simple oil reservoir attached to the head which ‘sprayed’ lubrication onto the area to be drilled.

The amount of oil being applied could not be controlled and so too much oil was being left in and around each hole.

It made the automated process unworkable since the Electroimpact procedure demanded that no oil is left in the hole when riveting occurs.

The solution was to incorporate the Bielomatik 2-CH MQL system, where a pressurised, small bore ring main delivers oil from a reservoir simultaneously, but separately, with a controlled air supply to a special Bielomatik rotary transmission unit.

A specially designed ‘quick valve’ attached to the rotary transmission unit then controls precisely the amount of lubricant released for optimum cutting performance, quality of finish and extended tool life.

On the A380 Airbus assembly line lubrication is delivered via Bielomatik’s MQL system through the cutting and countersinking tool whilst it is applied externally for the spot facing operation.

It has produced a vastly improved processing performance, optimising tool life and cycle times.

There is also the added benefit that removed metal cuttings are oil free and can be re-cycled more easily and at lower cost.