30.05.2012  Robotic cleaning line commissioned for aerospace

Cleentek Ltd have recently designed and commissioned a robot cleaning line for aircraft fasteners used in the UK manufacture of wings for a range of major new airliners. Working in close conjunction with Yaskawa Motoman Robotics, which has manufactured over 200,000 robots internationally, Cleentek completed the installation at J&P Group near Chester in only 10 days.

During production of the new airliner wings, huge numbers of fastening pins are inserted into the wings to hold them in place. A high performance industrial sealant used in the fabrication of the fuel tank cells is then injected into the wings, and the fasteners removed for repeated use.

Although the sealant cures very quickly, which is of clear benefit to the manufacturing process, it is very difficult to then remove. For the fastener pins, however, it is essential they are scrupulously cleaned of any contaminant in order to be used over and over again.

Also critical is the new cleaning line’s reduction in the use of solvents. Like all manufacturing organisations, aircraft companies are under pressure from their own environmental departments and external regulatory bodies to wherever possible reduce the use of hazardous cleaning solvents, and reduce or if possible eliminate emissions of volatile organic compounds (VOCs).

The new six-stage cleaning process is thought to be the most automated and efficient aircraft parts cleaning line anywhere in the world. Cleentek’s uniquely designed configuration also greatly reduces the use of solvent and is well enclosed from operatives feeding and emptying the line.

“The aircraft fasteners were previously cleaned using an ultrasonic cleaning system, which used two different solvents for removing sealant from the fasteners,” says Cleentek’s MD Kevin Whittle. “Following research and development over a two year period, Cleentek have devised a new robot cleaning process utilising aqueous cleaning processes and eliminating one of the solvents.”

Contaminated fasteners arrive at the line in plastic boxes which are then emptied by the robot into cleaning baskets, also placing the dirty boxes into a box cleaning machine. Working four baskets per batch, the fasteners then undergo a six-stage cleaning process: pre-wash, dry, ultrasonic cleaning, post-wash, rinsing with corrosion inhibitor, and dry.

The pre-wash system is a Cleentek Frontloader cleaning machine, which sprays a heated waterbased chemical on to the fasteners at high pressure to remove swarf and other loose contaminants. After the drying process, the fasteners are picked and moved by the robot to the next machine – one of two Cleentek Ultrasonic Cleaning Units fitted with an agitation system.

The Ultrasonic Unit heats the cleaning solution to 60 degrees Celsius and immerses the fasteners  for 20 to 30 minutes. The cleaning solution and the scrubbing action of the cavitation process break down and remove the sealant from the fasteners. (NB. All the cleaning chemicals used have also been custom formulated by Cleentek Ltd.)

The baskets of fasteners are then picked by the robot and moved to a  post-wash system in another Cleentek Frontloader specially fitted with three stages. First, the same waterbased chemical as the pre-wash removes any sealant not totally removed in the Ultrasonic Unit. The second stage rinse then deposits a small amount of rust inhibitor before the fasteners are dried in a  warm air blower.

Each full cycle lasts 30-40 minutes, after which the baskets of clean dry fasteners are taken to a filling station to be filled into their now clean boxes. They exit the line as they arrived, on a roller conveyor, and are then stacked and returned to the wing assembly lines, ready for re-use.

Based nearby in NW England, Cleentek Ltd is backed by a UK based engineering division and provides a wide range of standard and custom made component cleaning machines manufactured to high quality standards in accordance with the CE Machinery Directives. 

Besides aerospace, Cleentek Ltd and its Danish sister company supply equipment for many different applications and  industry sectors including automotive, food, general engineering, oil and gas, pharmaceuticals, printing, rail, remanufacturing and repair workshops.