What is an Ra Chart?

RA (roughness average) charts or surface finish charts can provide a great deal of information about thin aluminum strips, thin metal strips, aluminum sheets, and more. The surface finish report can describe finish parameters.

The Roughness Average or RA is the most common type of parameter used. It is a parameter used to calculate the average height of all valleys and peaks on the surface.

The Three Components of a Metal Surface

three components are used to measure the quality of 6061 aluminum, thin aluminum strips, and other combined metals. These three components are the lay, the waviness, and the roughness.

Roughness is one of the most important parts of surface attributes. Understanding what an RA report means and how to use it to your advantage is vital.

An RA chart focuses on the roughness of the surface. There are different methods for measuring the RA of the surface. Each method is valid. The type of metal can play a role in which testing method is used. For example. Ams 5510 may use the area techniques, while thin aluminum strips may use the profiling technique, and further sheet aluminum may use the microscopy technique.

What Does It All Mean?

There are different determinants used in an RA chart. The RA itself is the roughness average. It is often referred to within the metal industries as “centerline average” or the “arithmetic average.” It is the average between the mean line and the roughness. RA is the determinant that is most commonly used.

The Rmax is the vertical distance of valley to peak. This is often used for anomalies in metal sheeting, thin metal strips, thin aluminum strips, and more that have burrs or are scratched somehow. Rmax is a more sensitive measurement for anomalies in the metal finish.

The Rz is the average of the five greatest differences between the peaks and valleys. This test helps to eliminate some of the errors that can be missed with a simple Ra.

Reading the chart and understanding what you are reading is critical to ensuring that you are getting the quality metals you need for your production or customers. It helps with ensuring quality and ensuring that your metal supplier can meet your specifications.

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