QMT Features: September 2007
Microns = seconds
Super Aguri FI upgrades their metrology for the 2007 season in a drive to cut tenths of a second off lap times.

The  2006 Formula One season marked Super Aguri F1 Team’s debut, so it is unsurprising that the team did not win any championship points.  This year is a different story with the  team’s leading race driver, Takuma Sato, currently on four points after coming  eighth in the Spanish Grand Prix and sixth in Canada.  Just as important as Sato’s driving  skill has been the better mechanical reliability of the SA07 race car and its  improved aerodynamics, resulting in greater speed around the tracks.

Some  of the credit can be claimed by Metris which, as official metrology equipment  supplier to Super Aguri F1 Team, manufactured and installed an LK co-ordinate  measuring machine (CMM) large enough to accommodate a complete race car  chassis.  In addition, Metris has  supplied 3D laser scanning heads and software to upgrade and increase the  performance of a pre-existing Faro portable arm and a smaller Mitutoyo  CMM.

Super Aguri F1 Team’s financial constraints as a start-up team in a super-rich sport, allied with a need to utilise high-end metrology equipment to compete effectively in F1 races, was a fundamental dilemma.  The original measuring equipment was  able to cope in some areas.

However, the larger  structural elements of the car could previously only be inspected using the Faro arm, which was capable of no more than ±30 microns measuring accuracy, insufficient to chase those all-important lap time reductions measured in fractions of a second.  Moreover, comprehensive checking of profiles and surfaces was impossible to achieve by single-point probing on the Mitutoyo or Faro machines in the very short lead times between  races.

So  there was enthusiasm among the directors of Super Aguri F1 when Metris approached them in the close season offering to provide an LK CMM with 2,500 x 1,000 x 800 mm measuring envelope capable of ±2 microns  volumetric accuracy.  They also  suggested using Metris laser scanning heads and software on all three measuring  machines to speed the inspection of features and  surfaces.

Commented Tim Nolan, inspection manager, SAF1 Team base at the Leafield technical centre, “We are constantly trying to cut tenths of a second off lap times and to achieve that, we need to measure body panels and mechanical  components to within a few microns.  We could not achieve this on larger item such as a whole carbon fibre  body shell.

Another difficulty we had was an inability to capture data on freeform surfaces quickly to reverse-engineer external body parts after wind tunnel tests, as often the original CAD data was not available from the model shop, or the part had been modified by hand to optimise its  aerodynamics.

CAD  to part analysis of complex surfaces, such as carbon fibre patterns for which we  did have the data, was similarly problematic as digitising a surface by probing  discrete points was not fast enough at the frenetic pace that we  operate.”

The Metris Model Maker D laser scanner on the 7-axis Faro arm has a wide, single stripe and high frame rate for fast scanning, with the Metris Kube Scan software rendering the shape in real time on the screen.  Filtered scan data is exported to Metris Focus Inspection software for comparing the collected point cloud data with the  original CAD model and generating inspection reports. This all speeds the complete  process. The  higher accuracy of CMMs allows the use of the Metris XC50 and LC15 laser scanner  probes, both of which are compatible with Renishaw motorised probe heads and  auto exchange rack.  The XC50 uses  three laser stripes to view a component from different angles  simultaneously.  It scans complex  geometries and measures features at high speed to high accuracy in full 3D, making it especially useful for scanning holes,  slots and pockets as well as gap and flush between body  panels.

The  LC15 was utilised for the scanning of the foam for the race car seat, which is  bespoke to the driver and has to fit his form perfectly.  Mr Nolan said that in the past this took  two days using single-point probing, whereas the same job is now completed in  one hour. He  went on to explain how a touch probe and a laser scanning head can be used  sequentially to inspect a part on a CMM, the results being joined automatically by the Metris software into a single scan or inspection report. For instance, holes and machined  features on a chassis are checked using the ±2 micron  volumetric accuracy of the LK CMM in touch probe  mode. The  laser scanner, with ±8 micron  accuracy, then takes over to capture the profile, resulting in significant time  savings and an improvement in accuracy compared with using the Faro arm.  

Now that the  Metris equipment is in place at the SAF1 Team factory, the metrology infrastructure matches that of the top F1 teams, except for the absence of a  Metris Krypton optical CMM with 17 cubic metre measuring envelope for checking  the entire car after assembly.  F1’s  governing body, the Federation Internationale de l’Automobile (FIA), also uses such a machine to  carry out legality checks on participating cars before and after each  race. l

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