Stresstech offers advanced residual stress testing solutions

When placed near a magnet, steel emits a crackling sound known as Barkhausen noise. Named after professor Heinrich Barkhausen, who discovered the phenomenon, this noise varies depending on the amount of impurities and other properties of steel. Quality control expert Stresstech was the first company to commercialise the technique for testing the material strength of aircraft and vehicle parts such as camshafts and gears.

"The technology - though discovered already in 1919 - is new for quality control application and no one had used it for that before us," says Lasse Suominen, president of Stresstech in Finland. "Our clients get far better quality and more efficient production processes with our equipment."

Catering to the likes of Ferrari, Ford and Toyota, Stresstech's patented Barkhausen noise analysers can detect defects as fast as 0.2 seconds. Designed to identify residual stresses and hardness changes due to grinding burns, heat treatment defects and other residual stresses, Stresstech's Barkhausen noise analysers ensure longer lifespans for vehicle components. The non-destructive testing method is also environmentally friendly compared to traditional nital etching, which uses harmful chemicals.

Stresstech offers a full product range from single measurement sensors to fully customised automated inline systems. The RoboScan 600 system, for example, inspects different gear types using a fully programmable robotic arm.

"Research is important for us because we need to be always ahead," Suominen says.

As the Barkhausen technique applies only to steel materials, Stresstech has developed two more technologies for stress testing - X-ray diffraction and advanced hole drilling. X-ray diffraction gauges the stresses of crystalline metals and ceramics by measuring their interatomic distance changes, while Stresstech's hole-drilling method observes stresses by laser interference phenomenon.