Gaining a Competitive Edge

If you are an Olympic bobsled champion, how do you transfer the proven speed of hand-made blades into a new standardized material mandated by the sport’s governing body? An appeal in a German manufacturing technology magazine, Industrieanzeiger, by German Team Kiriasis, the world’s top two-person woman’s bobsled team, brought a partnership proposal from world manufacturing leaders Renishaw ( Wooton- under-Edge, England), Siemens (Munich, Germany), Sescoi (Sutton Coldfield, England) and Iscar (Tefen, Israel). Renishaw used its latest measurement technologies, including the revolutionary REVO™ ultra-high-speed measuring head for coordinate measuring machines (CMMs) to deliver precise data capture of the legacy blade geometry that had carried Team Kiriasis to a world championship in 2005 and Olympic gold at Turin in 2006.

Success at blade replication won Team Kiriasis both the 2006 – 2007 FIBT World Cup and World Championships. In fact, by running the new replica blades, the team won the world championship by more than two seconds, the biggest margin ever in championship history where races are usually decided by hundredths of a second. Using the blades again at the 2007 – 2008 World Cup, Team Kiriasis won again, making it the sixth straight title for Sandra Kiriasis, team captain and driver of the two-person sled.

The New Rules

The blade project arose following new rules introduced by the FIBT (International Federation of Bobsleigh and Tobogganing) in October, 2006. The new rules aimed to remove ongoing disputes over the use of various materials and treatments in blade manufacture. All bobsled teams must now use the same specification steel with creativity allowed only in blade form.

Kiriasis prized the competitive edge achieved by her existing blades, but as these had been created using manual techniques, there were no drawings or electronic CAD data to allow them to be re-manufactured using the new standard specification steel. The first step by the Renishaw-Siemens-Sescoi-Iscar partnership was to send the existing blades to Renishaw’s UK research facility. There, Renishaw’s revolutionary REVO five-axis measuring head for CMMs was used to scan the blades, quickly capturing many thousands of data points to enable form geometry to be defined in exact mathematical detail.

Unlike conventional touch scanning methods, which rely on speeding up the motion of the CMM’s three axes in order to scan quickly, the low-mass REVO head combines horizontal and vertical rotary axes to perform high-speed “infinite” positioning of the touch probe. A 3D measuring device in its own right, REVO does the direction-changing measuring work to minimize CMM motion errors. REVO’s low-mass, low-inertia design allows scanning at speeds of up to 500 mm/sec. and capture of 4,000 data points/sec. vs. 200 to 300 data points for conventional scanning.

Creating the Winning Blades

The vast number of data points work with enabled high geometric and contouring accuracy as well as very smooth surfaces. The finishing program for the runner surfaces ran 5MB and contained about 100,000 lines, producing surfaces almost as polished as a mirror.

Following machining, the finished blades were checked for form while still fixtured on the machine tool, using the Renishaw OMP400 touch probe with industry-leading strain gage accuracy. A patented strain gauge-sensing mechanism and advanced electronics allow lower, highly consistent contact forces with reduced pre-travel, enabling sub-micron 3D probe measurement and verification of the contoured surfaces.

Kiriasis was on hand to personally evaluate the machining. She received runners machined to exactly the same geometry as her championship-winning blades. Mounted to her sled, the new blades performed as well if not better than the old ones, continuing her edge over world-class competition. After taking the gold medal at the FIBT championships in St. Moritz with brakeperson Romy Losch, Kiriasis told TV broadcasters, “The blades are the secret of my success.”