1.1
SR200
Specifications subject to change
Chapter 1
Introduction to Surface Texture terminology and definitions
Surface Texture Definitions
Every components surface has some form of texture which varies according to its structure
and the way it has been manufactured. These surfaces can be broken down into three main
categories: Surface roughness, Waviness and Form. In order to predict a components behaviour
during use or to control the manufacturing process, it is necessary to quantify these surface
characteristics. This is done by using surface texture parameters.
Surface Texture Parameters:
Can be separated into three basic types: Amplitude, Spacing
and Hybrid.
Amplitude Parameters:
Measures of the vertical characteristics of the surface deviations.
Spacing Parameters:
Measures of the horizontal characteristics of the surface deviations.
Hybrid Parameters:
Combinations of spacing and amplitude parameters.
Mean Line:
Is a least squares line of nominal form fitted through the primary profile where
the areas of the profile above and below this line are equal and kept to a minimum separation.
Profile filters as detailed in ISO11562 define the mean lines for the roughness and waviness
profiles.
Cut-off:
A cut-off length (or sampling length) is a filter that uses either electronic (2CR)
or mathematical (Gaussian) means to remove or reduce unwanted data in order to look at
wavelengths in the region of interest.
Bandwidth:
Is the ratio of the upper Cut-off (Lc) to the lower Cut-off (Ls).
Sample Length:
The profile is divided into sample lengths l, which are long enough to include
a statistically reliable amount of data. For roughness and waviness analysis, the sample length
is equal to the selected cut-off (lc) wavelength. The sample length is also known as the cut-off
length.
Evaluation Length:
The length in the direction of the X axis used for assessing the profile
under evaluation. The evaluation length may contain one or more sample lengths. For the
primary profiles the evaluation length is equal to the sample length.
Rapp Industrial Sales 724 789-7853
