First Helicopter Blade Restraint Cradle Created with 3D Printing Technology

SFM Technology Limited is an independent, privately owned British company that develops and provides engineering solutions for particularly demanding environments. Recently, the company partnered with Big Rep 3D to fulfill an urgent request from the Royal Navy.

First established in 1985, SFM started working with the fast-evolving Aerospace Industry and in 1997 expanded further into both design and manufacturing services at their facility in the UK.

Leonardo's AgustaWestland AW101 helicopter manufactured for the British Royal Navy [Image courtesy Leonardo helicopters]



Because of their excellent reputation, Leonardo -- an aerospace and defense giant -- turned to SFM and their AeroAdditive division to provide a solution to a problem. Leonardo -- tasked by Britain's Ministry of Defense to provide AgustaWestland AW101 helicopters for the Royal Navy -- found that the helicopters' main rotor blade restraint cradles were not living up to their standard. They needed a new solution.

Well, rough seas not only make smooth sailors, they also make smooth engineers who can find innovative solutions to choppy conditions. This is especially true when it comes to aviation, as these helicopters are frequently tasked with landing on ships during all different types of weather conditions.

Main rotor blade restraint cradle for Leonardo's AgustaWestland AW101helicopters [Image courtesy BigRep GmbH]



Once the helicopter finishes flying, it will either stay on the flight deck or be stowed in the ship's hanger. These helicopters use software to automatically fold in their blades like a bumblebee. This helps with stabilization, which is a key priority when it comes to making the smoothest embarkation possible. The stabilization is achieved by using a main rotor blade restraint cradle.

"When a helicopter is on board a ship, it has the facility to fold its helicopter blades back," says Gary Wilson, head of Technical Sales at SFM's AeroAddtive division. "Once the helicopter blades are folded back at sea, it's still windy, and the blades can flap. So, these blades need to be restrained so this flapping doesn't occur."

3D Printing to the Rescue

Main rotor blade restraint cradles [Image courtesy Leonardo helicopters]



As a solution had to be found very quickly, SFM turned immediately to the possibilities of additive manufacturing.

As Mr. Wilson says, "This is quite a long process, so we had a look at many aspects of 3D printing. We must look at cost, efficiency, and of course, the size, which pushed us to BigRep. Eventually, we looked at the BigRep PRO as we had to look at a production 3D printer, which I believe the BigRep PRO can provide. The machine is used as a production machine, so every rotor blade restraint cradle will be going to the end customer."

3D Printing Provides Versatility

In the aerospace industry, lightweight yet strong parts are essential. SFM Technology found through stress-testing that their 3D-printed printed parts performed better than original, non-printed parts. By using Hi-Temp CF -- a carbon fiber reinforced material with versatile, high-strength properties -- the blades have a powerful resistance to wear and tear as well as any external pressure.

The benefits have been manifold. As Mr. Wilson attests, "To date, we have printed 30 cradles, consisting of 60 halves, since January. If we were to do that in a traditional way, we would have done about a quarter of that. So, you can see that 3D printing is far quicker, as we don't have any adjustments to make, or if we do, they're very minor and can be quickly overcome. And the material is just as strong."

Advantages if Hi-Temp CF

Choosing the right material was crucial for SFM.

The BigRep PRO is a powerhouse 3D printer built to take you from prototyping to production.



"We carried out many tests to establish which was the most suitable material within the budget given. Having looked at the data sheets, we felt that Hi Temp had a slight advantage over the other BigRep materials," says Wilson.

Once they remove the support material, they use sandpaper and its equivalents to smooth the surface. Then bushes are inserted in the hinges, before using helicoil inserts when required. Once the cradle is painted to the customer's specification, the rest of the metal parts are added along with the foam on the inside of the cradle, protecting the main rotor blade when the restraint cradle is fitted.

3D Printing in Aerospace Just Taking Off

With the main rotor blade restraint cradles already in use, Mr. Wilson attests that this experience shows what 3D printing can achieve in the aerospace industry and that it's only a matter of time before additive manufacturing becomes the norm.

VIDEO: BigRep PRO Industrial 3D Printer

"In the aerospace industry, there are many designers still slightly nervous about 3D printing. By using these cradles, we can demonstrate that 3D printing can be used in the aerospace industry quite comfortably from a strength, repeatability, and quality side. I know for a fact, that as the industry gets more technically forward on 3D printing, certainly there will be more and more paths because of the accessibility to them."

SFM Technology is now looking to use the BigRep PRO as a batch 3D printer, able to sequence production and create improved results across the board. It is likely that more aerospace designers will see the benefits of 3D printing and look to adopt it in due course.

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