It’s strong enough to support the weight of two African elephants and sturdy enough to deflect a large, full suitcase at a speed of 225kph. So how is motor sport’s new Halo device made to withstand such forces? The FIA’s AUTO magazine visited a manufacturer to find out.
It all starts with titanium. Lots of titanium.
“We had to buy about 10 tonnes of high-strength titanium within one-and-a-half months, and receive it all in time and in perfect quality,” says Steffen Zacharias of Germany’s CP Autosport, one of the three manufacturers chosen by the FIA as official suppliers of the new Halo safety device.
The device is made from Grade 5 titanium, which is extensively used in the aerospace industry and is known for its high strength and stiffness compared to its relatively low weight. Fortunately, CP Autosport is well-versed in dealing with the stuff.
“We have a long history in motor sport, being involved since the 1990s, but we have an even longer background in aerospace materials and fabrication,” says Zacharias. “We have been building titanium parts for aerospace and for outer space – for the EU’s Ariane rocket programme – and this background is where we come from and how we ended up in Formula One.”
This experience put CP in pole position when it came to producing the first Halo prototype for FIA testing. Alongside the UK’s SSTT and Italy’s V System, CP was tasked with building a prototype within six-and-a-half weeks to be tested at the Cranfield Technical Centre, in the UK, in October 2017.
It was the first company to pass the test and has been chosen by nine of the 10 F1 teams to supply Halos this season (although some teams have purchased the device from all three companies).
It helps that CP’s manufacturing facility was ideally matched for the task.
“You need state-of-the-art machining parts to do the pre-machining and the post-welding final machining,” explains Zacharias. “You need a welding chamber in a closed atmosphere to do the welding process, and you need the supply chain for the material.”
Before working with the titanium it must be heat-treated to be optimised for the task. The company generally receives forged blocks that have been pre-treated to an individual CP specification to help withstand the loads that the final device will face.
“We have been given a challenging load case that the Halo should perform to in the physical test,” says Zacharias. “One thing to give a part function is the geometry, but when it comes to welding and metallurgy the heat-treatment process is one of the key drivers. With the heat treatment you set up the physical strengths of the part in combination with the geometry.”
The next step is to pre-machine and gun-drill the tubes that will be welded together. The Halo itself is built from five different parts. The half ring at the top is made from two quarters of the circle. Then there are the two end pieces that attach to the back of the car and the centre pillar in front of the driver.
The welding process is performed in a closed chamber to prevent any foreign objects from interfering with the material. The whole device then undergoes further heat treatment for additional strengthening before it is sent for testing.
“The challenge is definitely in forming the tube in this titanium five-grade condition without weakening it,” says Zacharias. “And then having the heat treatment in the right set-up. Heat treatment is one of the technical tricks you need to bring in to make the parts work as they are supposed to.”
Only the refernce production device is tested to destruction at Cranfield. Each subsequent device is made from an exact process sheet that is approved by the Global Institute for Motor Sport Safety, the FIA’s safety research partner. But every device is geometry-checked, weight-checked and undergoes non-destructive testing, including x-rays and crack tests.
“We do these tests in-house,” says Zacharias. “Coming from the aerospace industry, we have a very intense testing area, including physical test benches and life-cycle testing. We test all our parts in-house by certified people to an aerospace standard.”
The x-ray test involves an approved engineer screening all of the welding seams and this is followed by a dye penetration test to check for any cracks in the material. Then an ultrasonic test is used to ensure that the wall-thickness of the tube is the same at every point. No area is left unchecked.
Once complete, the Halo is manually shot-cleaned to create an abrasive surface that makes it easier for teams to attach any aerodynamic parts that are permitted by the FIA. This does not modify the strength of the material or put any stress on the parts.
All of these steps are essential to producing such a high-performance device. The Halo has to withstand 125 kiloNewtons of force (equivalent to 12 tonnes in weight) from above for five seconds without a failure to any part of the survival cell or the mountings. It must also withstand forces of 125 kN from the side. Without question, it is now the strongest element on
a Formula One car.
“It has been a task to bring all the production technology together in a part like that,” says Zacharias. “We have been producing titanium structures for years but to bring it all together – the machining, the gun-drilling of the material to produce a tube with such wall thickness, the welding process and geometry from all five parts coming together, and the heat-treatment process – to meet this precise window of technical function, that was the main task. Each field itself was like what we have been used to, but to nail it down together in six-and-a-half weeks, that was the hardest task.”
It helped that the F1 teams were fully supportive at every step of the way.
“I’ve been in this business now for almost 20 years and I have never experienced such an open-door philosophy from the teams,” admits Zacharias. “Whatever question we had, whichever expert we needed to talk to, we have been connected. Every door has been opened.”
Clearly, the F1 teams have been doing everything they can to help integrate the Halo onto their cars. Although a huge effort has been made to decrease the weight of the device, each one still comes in at 7kg, a not insignificant element for an F1 chassis to deal with.
“Adopting it has been a significant challenge,” admits Mercedes Technical Director James Allison. “It’s several kilograms of titanium that needs to be put on the car, and all of the changes that we needed to do to accommodate it had to be made so that the overall car would still stay below the weight limit.”
The main issue was to make sure the rest of the chassis would match the strength of the Halo to ensure it all works uniformly.
Allison adds: “We had to strengthen the chassis so that it would take roughly the weight of a double-decker bus sitting on top of this Halo to make sure it is strong enough to withstand the type of event it’s designed to protect the driver’s head against.”
This is why each team has purchased numerous Halos, some from all three suppliers. As always in F1, the pursuit of the perfect package has been unceasing.
CP has already produced and shipped 70 Halos and is expecting to have made 100 by the end of March. Not only is it supplying nine of the 10 F1 teams, it is also supplying the F2 and Formula E championships, which are then distributing to their teams.
But CP is grateful to have won this responsibility. When the F1 teams line up on the grid for the first race of the season it will be a proud moment for the company.
“We have 200 people working here and we usually produce parts that are underneath the car and covered up by carbon fibre,” says Zacharias. “So to be able to show a physical part that’s more visible to the public means our employees can say, ‘this is what we’ve been working on, and this is what drives me to stay longer to fulfil my job and overcome obstacles that others may be stopped by’. So yeah, that really makes us proud.”