Varities of Surface Roughness

The definitions and notation are prescribed for the parameters which indicate the surface roughness of an industrial product, including the arithmetic average roughness (Ra), maximum height (Ry), 10-spot average roughness (Rz), average concave-to-convex distance (Sm), average distance between local peaks (S), and load length rate (tp). Surface roughness is the arithmetic average of values at randomly selected spots on the surface of an object.

[Center-line average roughness (Ra75) is defined in the supplements to JIS B 0031 and JIS B 0601.]
 

Typical Calculation of Surface Roughness

 

Reference: Relationship between Arithmetic Average Roughness (Ra) and Previous Notation.

∴ The relationships among the three varieties shown here are not precise, and are presented for convenience only.
∴ Ra: The evaluation lengths of Ry and Rz are the cut-off values and the reference length each multiplied by five.
 

Typical Calculation of Surface Roughness

An auxiliary symbol indicating a surface roughness value, cut-off value or reference length, machining method, grain direction, surface undulation, etc. is placed around the surface symbol as shown in Fig. 1.

 

Comparison of National Standards of Surface Texture Measurement.

Definition of Surface Texture and Stylus Instrument.

Measuring Condition: R-Parameter (ISO4288: ’96)

Measuring Condition: P-Parameter (ISO4288: ’96)

Measuring Condition: P-Parameter (ISO1302: ’02)

Basic Surface Textures Parameters and Curves

Expended Surface Textures Parameters and Curve

Above sharing just for your reference. When you’re interested in investing a Surface roughness tester to improve your quality process, select a supplier who offer a quality service and meet your specific needs.

If you have any enquiry with dimensional equipment, welcome to contact us by email: enquiry@mspmetrology.com