Barkhausen noise in practice: Part geometries

Nearly all kinds of sample geometries can be analyzed with Barkhausen noise.

Successful testing has been performed on areas less than a millimeter and up. Barkhausen noise sensors require proper access and contact with the area to be analyzed. In order to create sufficient magnetizing flux density at the areas being tested, our sensors are designed to optimize the contact area between the sensor tips and the test surface:

  • Larger pick-up areas enable faster measurements, but a smaller pick-ups provide greater resolution
  • Optimizing the sensor pick-up and contact area provides the best balance between speed and resolution of the tests

Geometries can be tested by hand or via automation, using spot checks or surface scans with mapped results.

Various geometries can be measured, and we use the following designation: Regular and Complex.

Regular geometries

Regular geometries

Complex geometries

Complex geometries

Regular geometries

Measuring surfaces with regular geometries with Barkhausen noise analysis

Flat

Flat surfaces of different sizes can be analyzed with Barkhausen noise. There is no limit to how big the surface can be, but areas smaller than 25 mm² do have physical limitations. Ground flange surfaces are a typical example of flat surfaces analyzed with Barkhausen noise.


Typical sensors for flat surfaces: Flat sensors, General Purpose sensors

Flat surfaces

Convex and cylindrical

Convex and cylindrical surfaces of different sizes can be analyzed with Barkhausen noise. There is no limit to how big the surface can be, but diameters smaller than 10 mm do have physical limitations. Sensor tips for convex and cylindrical shapes can be designed to follow the surface shape or be universal to scan a range of diameters. Cylindrical surfaces like crankshaft and camshaft bearing journals are common surfaces to be analyzed with Barkhausen noise.

Typical sensors for convex and cylindrical surfaces: Camshaft sensors, Pick-up sensors, OD sensors, Flat sensors, Crankshaft OD sensors

Convex and cylindrical surfaces

Holes

Holes of different sizes can be analyzed with Barkhausen noise. There is no limit to how big the surface can be, but holes with diameter smaller than 6 mm do have physical limitations with sensor fitment. Typical holes to be analyzed with Barkhausen noise are e.g. holes in fuel delivery components.

Typical sensors for holes: Pick-up sensors, ID sensors

Holes surfaces

Concave

Concave surfaces of different sizes can be analyzed with Barkhausen noise. There is no limit to how big the surface can be, but shapes with radius smaller than 1 mm do have physical limitations. Adjacent areas to must not block access to the surface to be tested. Typical concave surfaces to be analyzed with Barkhausen noise are e.g. crankshaft journal radius surfaces (fillets).

Typical sensors for concave surfaces: Pick-up sensors, ID sensors, Crankshaft Radius sensors.

Concave surfaces

Conical

Conical surfaces of different sizes can be analyzed with Barkhausen noise. There is no limit to how big the surface can be, but the amount of variation between diameters is limited for each sensor design. Diameters smaller than 10 mm do have physical limitations, especially when measuring in circumferential direction.

Typical sensors for conical surfaces: Pick-up sensors, OD sensors, Flat sensors.

Conical surfaces

Spherical

Spherical surfaces of different sizes can be analyzed with Barkhausen noise. There is no limit to how big the surface can be, but diameters smaller than 10 mm do have physical limitations. The sensor tip for spherical shapes can be designed to follow the surface shape/contour or be universal to scan different diameters.

Typical sensors for spherical surfaces: Pick-up sensors, OD spherical sensors.

Spherical surfaces

Complex geometries

Measuring surfaces with complex geometries with Barkhausen noise analysis

Cam lobes

Cam lobes of different sizes can be analyzed with Barkhausen noise. When scanning cam lobes, the contact angle of the sensor varies during the cam lobe rotation. Camshaft sensors are designed so that these variations have a minimal effect on the sensor’s signal quality. Cam lobes narrower than 6 mm do have physical limitations, but there is no upper size limitation. Special sensors can be designed when there is little or no space between the lobes.

Typical sensors for cam lobes: Camshaft sensors, OD sensors.

Cam lobes surfaces

Cam rings

Cam rings of different sizes can be analyzed with Barkhausen noise. When scanning cam rings on ID surfaces, the contact angle of the sensor varies during the scan over the concave and convex shapes. Camshaft sensors are designed so that the angle variations have a minimum effect on the sensor’s signal quality. Inner diameters smaller than 20 mm do have physical limitations with sensor fitment when testing, but there is no upper limit.

Typical sensors for cam rings: Camshaft sensors, ID sensors.

Cam rings

Gears

Gears have several different surfaces that can be analyzed with Barkhausen noise. Typically, with Barkhausen noise analysis, gear tooth surfaces are divided into flank/face, and fillet radius/root.

There is no upper limit to the size of gears can be analyzed but gear teeth smaller than module 2 may have physical limitations with sensor fitment. As the tooth surface is convex and the sensor contact is line shaped, it may require several scanning routes for scanning the whole tooth.

There are different kinds of sensors for different gear surfaces. In some cases, depending on the gear geometry, the same sensor can be used for all the tooth surfaces.

Outer spur gears, outer helical gears, outer straight bevel gears, and rack and pinion gears

Outer spur gear, outer helical gear, outer straight bevel gear, and rack and pinion gear teeth can be analyzed with Barkhausen noise. The gear flanks/faces are scanned with a straight sided sensor, and fillet radius/root requires a sensor with rounded sensor tip.

Typical sensors for outer spur gears, outer helical gears, outer straight bevel gears, and rack and pinion gears: Gear flank sensors, Gear root sensors.

Outer spur gears, outer helical gears, outer straight bevel gears, and rack and pinion gears

Inner spur gears and inner helical gears

Inner spur and helical gear teeth can be analyzed with Barkhausen noise. The gear flanks/faces are scanned with a sensor for inner teeth, and fillet radius/root requires a sensor with rounded sensor tip. There is no upper limit for gear size but note that the sensor must fit inside the center section of the gear.

Typical sensors for inner spur gears and inner helical gears: Gear flank sensors for inner teeth, Gear root sensors.

Inner spur gears

Spiral bevel gears, hypoid gears, and worm wheels

Spiral bevel gears, hypoid gears, and worm wheel faces/flanks can be analyzed with Barkhausen noise. The sensor head for compound curved surfaces is shaped so that it enables a proper contact with the surface. Sensors for compound curve surfaces need to be geometry and size specific. Therefore, one sensor has a limited size range for parts that can be scanned.

Typical sensors for spiral bevel gears, hypoid gears and worm wheels: Bevel gear and pinion sensors.

Spiral bevel gears, hypoid gears, and worm wheels

Worm gears

Worm gear faces/flanks can be analyzed with Barkhausen noise. The design and type of sensors for worm gear testing depends on the geometry and size of the part. There are many tested and verified solutions available.

Typical sensors for worm gears: Bevel gear and pinion sensors, Gear flank sensors.

Worm gears

Ball screws

Ball screw grooves can be analyzed with Barkhausen noise. The design and type of a sensor for ball screws depend on the geometry and size of the part. Outer diameters smaller than 10 mm and groove sizes smaller than 2 mm do have physical limitations with sensor fitment when testing, but there is no upper limit.

Typical sensors for ball screws: OD groove sensors.

Ball screws

Ball screw nuts

Ball screw nut grooves can be analyzed with Barkhausen noise. The design and type of a sensor for ball screw nuts depend on the geometry and size of the part. Inner diameters smaller than 30 mm and groove sizes smaller than 2 mm do have physical limitations with sensor fitment when testing, but there is no upper limit.

Typical sensors for ball screw nuts: ID groove sensors.


We provide Barkhausen noise inspection systems for a wide range of steel components in following automation levels:

RoboScan

Inline/Robot Systems

RoboScan is an automated grinding burn and heat treatment defect detection system that can be integrated into production line.

GearScan 500 and user

Automated systems

Automated systems for quality inspection are tailored for offline use. Easy to use software makes inspections intuitive and systems can adapt to various component types.

CrankScan 200 with user

Semi-automated systems

Semi-automated and manual Barkhausen noise analysis systems are suitable for low volume measurements. The most simple Barkhausen noise measurements can be performed handheld with only a sensor and analyzer.

Barkhausen noise analysis with Rollscan 350 and general purpose sensor.

Manual systems

Manual Barkhausen noise stands are grinding burn and heat treatment defect detection systems for low-volume applications.