Advantages in N Grade Surface Roughness

How can we make a way to identify material’s roughness easier from the manufacturer’s perspective in technical drawings? 

Surface Roughness, often called Roughness, is the deviation of a surface from its ideal form. Larger deviations from the ideal surface correspond to a rough surface, similarly, smaller deviations from the ideal surface show a smooth surface. “Ra” is commonly used to indicate the level of surface roughness. Other common parameters include Rz, Rq, Rt, etc. In total there are at least 24 different ways of specifying the roughness. All these parameters serve the different purposes of measurement; however, from a Product Owner’s point of view, they can become overwhelming.  

Thankfully, ISO has categorized these parameters using the N Grades (new ISO Grade Scale Numbers). They range from N1 to N12 and most of the 24 different ways can be mapped to an N-grade which could reduce the complexity that needs to be handled. So, what would be the complexity from the manufacturer's side?   

Certain parameters not only vary with type but also depend on the unit of measurements. This granularity of the parameters can be lost during the conversion means some minor values may be lost. As a result, it provides estimated rather than exact values. N Grades, on the other hand, are independent of the unit measurement, making them easier to apply. 

Even though the standard issuing N Grades was no longer used by ISO, it can still prove to be favourable when simplicity becomes prominent. Due to its Advantages our team recommends using N-Grades.  

Werk24 converts surface roughness parameters to N-Grades based on the following table.