Welcome To Our Website. Any questions about PCD cutting, brazing and grinding, Call Us:+86 17700605088

The Difference Between Ra and Rz

2020-10-19 11:29:32

 

 

The methodology of measurement and what is measured when calculating Ra and Rz are quite different. This is critical to understand if you will not be paid for your parts because the Ra you measured is not in fact the Rz surface profile that customer specified.

 

What is Ra?

What is Ra

 

Ra is calculated by an algorithm that measures the average length between the peaks and valleys and the deviation from the mean line on the entire surface within the sampling length. 

 

Ra averages all peaks and valleys of the roughness profile and then neutralizes the few outlying points so that the extreme points have no significant impact on the final results.

 

What is Rz?

What is Rz

 

“Rz is calculated by measuring the vertical distance from the highest peak to the lowest valley within five sampling lengths, then averaging these distances. Rz averages only the five highest peaks and the five deepest valleys—therefore, extremes have a much greater influence on the final value.”

 

Ra is the arithmetical average value of all absolute distances of the roughness profile from the center line within the measuring length.

 

Rz is the average maximum peak to valley of five consecutive sampling lengths within the measuring length. 

 

Ra averages all measurements and does not have any discriminating value in separating rejects from acceptable cylinders.”

 

When you want the better surface roughness of your parts, please feel free to contact More Super Hard, our experienced sales engineer will service for you.



  • How to resharpening PCD woodworking tools?
    25 June 2025

    How to resharpening PCD woodworking tools?

    "Learn why resharpening PCD woodworking tools with ceramic diamond grinding wheels is crucial for optimal performance. Discover how using 400# and 800# wheels prevents tool chipping, improves surface quality, and extends tool life."

  • High-Efficiency Grinding of PDC Cutters with Ceramic Diamond Grinding Wheels
    01 May 2025

    High-Efficiency Grinding of PDC Cutters with Ceramic Diamond Grinding Wheels

    Moresuperhard recommends ceramic bond diamond grinding wheels for the rough grinding of the cylindrical surface of the diamond layer on PDC cutters. These wheels demonstrate excellent efficiency and cost-effectiveness compared to traditional resin bond wheels.

  Add:  Zhongyuan Rd, Zhongyuan District, Zhengzhou, 450001, Henan, China

  Tel: +86 17700605088

  WhatsApp:+86 17700605088

  E-mail: pcd@moresuperhard.com