Kern Ultrasound hardness testing device is ideally suited for mobile hardness testing, where the main emphasis is on obtaining rapid and precise results. The SAUTER HO measures using a Vickers Diamond tip, which is pressed into the test piece with a defined force. After that the tip is moved into high-frequency ultrasound vibrations, the hardness is derived from the attenuation. Ideal for measuring small forgings, castings, welding points, punched parts, casting tools, ball bearings, flanks of gear wheels and for measuring the influence of warmth or heat.

• Advantages compared with Rockwell and Brinell: Less test force and therefore only microscopic, small penetrations means that the testing is less destructive

DIN 50159-1-2008, ASTMA1038-2005, JB/T9377-2013

Parallels, Surface Finish & Hardness

Surface Finish

Any machined component has a surface geometry which consists of three basic elements:

Form or Curvature - Whether the surface has irregular bumps or dimensional changes
Waviness - Whether the surface has regular repetitive ripples or patterns (e.g. milling patterns)
Roughness - The shapes or irregularities that are smaller than, and form part of the waviness pattern (e.g. material micro-structure)

Waviness and roughness are traditionally the most difficult elements to measure when comparing surface finish, however, they have a radical effect on the performance of the finished component. Variations will cause aesthetic appearance changes, component wear variations, oil retention variation etc. Many manufacturers therefore specify a range of roughness values which their components should be manufactured to, often expressed as: Ra, Rq (RMS), RzDIN, Ry, Sm,mm.