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Surface finish Ra and Rz
Q. We are regularly machining Cylinder Heads & Blocks. For Head contact face in case of Block and block contact face in case of head specifies surface finish of 15 Rz. After finish milling when we check for Rz it is between 15 to 20 Rz. But if we check Ra it is within 1 µRa. Can you please explain the difference between Ra & Rz measurements and in which specific application Rz is more important?
Thanks & Regards,
automobile manufacturer - Pune, Maharashtra, India
A. Ra vs Rz is like comparing inches to meters. They are not compatible. Use one or the other not both.
Nova Finishing Systems Inc.
March 31, 2009
A. Ra and Rz are different parameters of roughness.
- pune, maharashtra, India
December 21, 2010
Q. I am a production engineer in my concern,
Pleasw give the explanation about the following symbols
Above finish is required in a hole dia. 12.5 H7.
Please explain briefly with figures.
- pundhucherry, india
June 24, 2015
A. Rz is the sum of maximum peak and maximum valley of a profile, while Rmax is only the value of maximum peak of the profile.Karthik Muniappan
Quality engineer - Chennai,Tamil nadu,India