Dome grinder
A dome grinder , also called a calotester , is used to determine the layer thickness of individual layers and layer systems. A steel ball lies on a motor-driven shaft and at the same time on the sample part that is held at an angle. A spherical cap is ground into the surface to be tested with the ball and a little diamond grinding paste down to the base material. Since the diameter of the sphere is known, the layer thickness can be calculated by measuring the spherical cap under a microscope .
application
With a dome grinder it is possible to determine the layer thickness even if non-destructive processes cannot be used due to the material properties. These include in particular PVD ( physical vapor deposition ) and CVD ( chemical vapor deposition ) coatings .
Calculation of the layer thickness
After measuring the dome under a microscope, the layer thickness of the coating can be calculated using the following formula:
With:
- h = desired layer thickness
- D = circle diameter on the surface
- d = circle diameter at the boundary between layer and base material
- R = radius of the grinding ball
Web links
- Layer thickness measurement with the calotte grinding method (Calotest)
- Dome grinder on the website of the Chair for Surface Technology at RWTH Aachen University
Individual evidence
- ↑ Dome grinder. In: Chair for Surface Technology in Mechanical Engineering at RWTH Aachen University, Univ.-Prof. Dr.-Ing. K. Bobzin, D-52072 Aachen. 2020, accessed April 7, 2020 .
- ↑ Calotest Anton Paar dome grinder. In: Prof. Dr.-Ing. Dietmar Schorr, Steinbeis Transfer Center Tribology in Application and Practice, D-76133 Karlsruhe. 2020, accessed April 7, 2020 .
- ↑ Dome grinding process website of the Fraunhofer Institute for Surface Engineering and Thin Films IST. Retrieved September 3, 2018.