Sinusoidal profile precision roughness specimens

The design, specifications, fabrication, testing and potential use of a series of sinusoidal profile precision roughness specimens are described. These specimens were designed primarily to provide a means for optimum transfer of an accurate roughness average R a value from primary to secondary laboratories. However, properties of the specimens also make them very useful for evaluating instrumentation and computational algorithms designed to measure the statistical parameters and functions now being investigated in many laboratories. Specimens with an R a value of 1.0 μm and spatial wavelengths of 40, 100 and 800 μm are being fabricated. For the wavelength of 100 μm, specimens are also being fabricated with R a values of 3.0 and 0.3 μm. Fabrication using numerically controlled diamond lathes has produced specimens with very high quality sinusoidal profile waveforms with uniform R a values across the surfaces and with very low amounts of waviness over a test area of about 2 cm 2.