And not just any fan blade, but a monocrystalline blade destined to join 19 others in a $42 million Rolls Royce Trent 1000 jet engine. We are fortunate to be located in Indianapolis, home of Rolls Royce jet engine North America located just down the road from SILCA.
Here I would learn about the amazing laser welding technology that had been developed to fabricate and repair titanium jet engine components, and I have to say that I sort of fell head over heels in love with this fascinating technology.
Why laser weld?
For starters, laser welding offers more than 10 times tighter process control than we could achieve with a human welder, and this improvement in process control allows us to weld ever thinner walled tubing with ever higher certainty of achieving a perfectly perfect weld with essentially no Heat Affected Zone.
Why Thinner Walls?
With thinner walls, we can make the cage from larger diameter tubing, in this case, 6.35mm diameter 3/2.5 Ti tubing which is used for aircraft hydraulics. This tubing has 0.35mm wall thickness.. that’s the equivalent of 4 sheets of white copier paper!! For the seam-weld on the Ti sicuro cage, the laser can control the penetration depth of the weld to 0.005mm which allows us to perform the mythical Double-Pass weld.
What is Double Pass welding?
Made famous in the bicycle industry by Moots and Eriksen, as the name implies, the Double-Pass weld involves welding each joint 2 times. The first pass is a deep penetrating weld to ensure the weld is penetrates and connects 100% of the material in the joint. The second pass welds a larger surface area of the substrate and builds a smooth (and beautiful) fillet of material between the two surfaces which also serves to reduce stress concentrations in the joint under heavy loading.
The downside of Double-Pass welding is that it requires exceptional skill and is only achievable by the finest of welders without adding too much heat to the weld which can embrittle the material. This is what’s known as the Heat Affected Zone or the HAZ.
Why no HAZ?
With laser welding, there is virtually NO HAZ! Each pulse of the laser lasts 4 milliseconds, in which time the titanium hit by the laser pulse reaches 4000 degrees F and turns to nearly the viscosity of water, flowing together in a wave and then nearly instantly solidifying.
The extreme process control allows us to run a first pass of some 60 pulses at full penetration depth ensuring the strongest possible weld, then overwelding with another 60 pulses of wider, lower penetration weld bead to create the smoothest possible transition from tubing to weld which reduces stress concentrators and makes for a more beautiful weld.
Similarly, the laser enables the most perfectly perfect welds between the 1.1mm thick mounting plate and the 0.35mm wall tubing. Each weld is done in 2 passes, first penetrating the full 0.35mm deep into the tubing (without blowout!) and a second pass building a smooth fillet of weld between the plate and weld for optimal strength and beauty.
Perhaps most amazing is that the welding process introduces so little heat into the part that you can touch the part right after welding as it isn’t even hot!! By eliminating more than 98% of the heat which would be put into the part by traditional welding methods, we can guarantee welds of the absolute highest strength and durability which is why we are able to extend our Lifetime PLUS 25 year SILCA Shield warranty to the Sicuro Ti cages.
Why SILCA Shield?
SILCA Shield is the strongest warranty coverage in all of cycling. It covers the buyer for life against manufacturing or materials defects PLUS covers fatigue and usage based failures for 25 years, which are the hidden pitfalls of the standard ‘Lifetime Warranty’.