Surface Texture Parameters

Professor ： R. J. Chang

Student ： R. Z. Huang

Date ： 2004 / 04 / 14

Surface Texture Parameters

Amplitude Parameters Spacing Parameters Hybrid Parameters ADF and BRC Parameters

Roughness Amplitude Parameters

Ra Rq Rt 、 Rv 、 Rt Rtm 、 Rvm 、 Rtm Rymax Rz

Ra - Average Roughness

Continuous:

Discrete:

Ra is Not the End of the Story

These three surfaces all have the same Ra, even though the eye immediately distinguishes their different general shapes.

Rq - Root-Mean-Square Roughness

Continuous:

Discrete:

Rq is more sensitive to peaks and valleys

Rt, Rp, and Rv

Rtm, Rpm and Rvm

Rymax (or Rmax) and Rz

Rz(DIN), i.e. Rz according to the German DIN standard, is just another name for Rtm in the American nomenclature

Rymax (or Rmax) - Maximum Roughness Height Within a Sample Length

Roughness Spacing Parameters

Sm - Mean Spacing

Roughness Hybrid Parameters

Dq - RMS Average Slope

Continuous:

Da - Average Absolute Slope

Discrete:

Discrete:Continuous:

Statistical Analysis

The Amplitude Distribution Function

Rsk -Skewness

Continuous:

Discrete:

The Bearing Ratio Curve

tp as a parameter refers to the bearing ratio at a specified height

The bearing ratio curve is the integral (from the top down) of the ADF

Advanced Statistical and Bearing Ratio Analysis

Rk is the vertical height between the left and right intercepts of the - line through the ends of the minimum Htp 40% window.

This part of the surface is called the "core roughness"

Rk 、 Rpk 、 Rvk 、

MR1 、 MR2 、

A1 and A2 are determined by BRC

Rpk 、 Rvk 、 MR1 and MR2 Rpk Rpk is an estimate of the small peaks above the main plateau of

the surface. Rvk Rvk is an estimate of the depth of valleys which will retain lubri

cant in a functioning part. MR1 MR1 is the fraction of the surface which consists of small peaks

above the main plateau. MR2 MR2 is the fraction of the surface which will carry load during th

e practical lifetime of the part.

A1 and A2 A1 The "area" of the peak portion of the bearing ratio c

urve is denoted by A1. It is related to Rpk and MR1

A2 The "area" of the valleys in the Rk construction is de

noted by A2. It is related to Rvk and MR2:

Reference

http://www.predev.com/smg/parameters.htm#tp%20-%20Bearing%20Ratio

http://www.fujimfg.co.jp/benri/roughness.htm

http://www.htskorea.com/tech/spm/profile.pdf