Paul Rogger, technical director at JR Technology Limited (JRTL), explains how a partnership with two specialist companies led to the development of a solution to add material to four large automated fibre placement (AFP) mandrels used by GKN Aerospace to make the Airbus A350 XWB-1000 rear wing spar sections. When it comes to devising a solution for laying down additional composites material on tooling, that is quick, accurate and saves money, aerospace manufacturers are increasingly turning to specialist suppliers like JRTL.
In partnership with Composite Tooling and Engineering Solutions (CTES) and Retrac Composites, JRTL developed an innovative solution to add material to four large automated fibre placement (AFP) mandrels, composite tools used by GKN Aerospace to make the Airbus A350 XWB-1000 rear wing spar sections.
Imagine being faced with the prospect of weeks tracking down a very large autoclave or oven to accommodate large AFP mandrels, not to mention being up against an already tight manufacturing programme.
This was the scenario faced by CTES and Retrac when they turned to us to help them find a solution to apply additional material to four AFP mandrels. To put their problem in context, let's quickly look at how this particular mandrel is made.
Each mandrel comprises three sub-sections of carbon fibre/epoxy prepreg laminate which measure approximately four and a half metres in length. The sections are bonded together then the surface is machined to the final geometry, 3-5mm of excess material thickness being removed in the process.
However, when one of the AFP mandrels got to this stage it was evident there wasn't enough material to machine off. Furthermore, as the three sub-sections of the mandrel had already been bonded together it was now nearly 14m long and weighing 2.75t. Clearly, putting on more prepreg laminate and curing it now posed a much bigger problem.
And therein lay the rub for CTES and Retrac. When approaching a large-scale bonding project like this, the two companies would traditionally use either an autoclave or oven to cure the surface material, as they had no other way of getting enough heat to it.
But if they were to go down this tried and tested route, CTES and Retrac potentially faced weeks of tracking down an autoclave big enough; there are not many in the UK or Europe. There would also have been the additional headache of incurring costs and man hours to transport the mandrels to the autoclave. Alternatively, they could construct a temporary oven but this option posed a problem as it would be difficult to control the temperature in such a large space, and they didn't have the time to commission a new oven.
It goes without saying that CTES and Retrac were not only in a quandary, but they were also up against a tight manufacturing deadline. They needed to find a local solution to the problem, and fast - so they approached JRTL.
As you can imagine, this particular scenario was like music to our ears. We have been serving many industries, including aerospace - both civil and military - since 1979, providing specialist composite production tools and equipment to enable test and repair. Given this experience, there isn't much we haven't seen.
Composite tools like the AFP mandrel are vital in the manufacture of the Airbus A350 XWB-1000 rear wing spar, so it's essential that aerospace manufacturers like GKN are reassured the tool will be manufactured both quickly and accurately in order for their production timetables not to be delayed.
When CTES and Retrac told us their dilemma, we knew we could provide them with a solution which would save time, money and ensure accurate temperature control.
After careful consideration, we supplied eight short wave infra-red (IR) lamps and an Applied Heat A-150-LB Hot Bonding Controller with multiple heater mats. We chose this particular equipment as it allowed engineers to accurately control the cure of the additional prepreg laminate in many areas at the same time. Total time to complete the work was around six hours.
As you can imagine, the geometry of the tool didn't allow for the sole use of the controller, so the infra-red lamps were brought into service to apply heat locally in complex areas of the tool. In addition local vacuum bags were used to apply pressure in all areas.
As Liam Moloney from CTES pointed out: “The combination of the IR lamps and the hot bonding controller provided by JRTL gave us the control we required for the cure cycle we needed to do the work. Later in the manufacturing process it was found that the same equipment could be used to reduce the curing time of the surface sealer from 18 hours to 1½ hours.”
Another benefit was that the IR lamps and controllers are portable, so in the future, if there is a requirement for these tasks, CTES and Retrac will be able to carry out work on site for GKN. Indeed, following the AFP mandrel project, they have already used this equipment for rectification work with another client.
All in all the equipment JRTL supplied to CTES and Retrac meant they applied the additional material to the four APF mandrels in hours rather than days. Our innovative solution saved CTES and Retrac money and time whist also ensuring the highest manufacturing quality of the mandrels was maintained.
Our products are approved by Boeing, Airbus, Westland Helicopters, Rolls-Royce, Bombardier, NATO and other OEMs and organisations. Many of the major international airlines purchase our products and they are also specified in aircraft service repair manuals.
So, remember, if you're faced with having to work on a bonded structure and are up against a tight deadline, contact JRTL, as we can provide innovative solutions to even the most demanding of scenarios.