MANUFACTURING – CNC MACHINING CALCULATOR
Surface Roughness Ra
A precise tool.
What is the Surface Roughness Ra & How does it work?
Surface roughness Ra (arithmetical mean deviation) quantifies the average height variation of a machined surface and directly influences functional performance such as fatigue life, sealing ability, and aesthetic quality.
In CNC milling the dominant contributors to Ra are the feed per tooth (f) and the tool’s corner radius (r). A larger feed creates deeper scallops, while a larger corner radius smooths the peaks, reducing the overall roughness.
The calculator below uses the standard relationship Ra = frac{f^{2}}{8 r} to estimate the roughness. Enter the feed and corner radius to obtain an immediate Ra value in micrometres.
Ra = \frac{f^{2}}{8 r}
f = feed per tooth (mm), r = corner radius (mm)
Parameters
Result
—
Frequently Asked Questions
What is surface roughness Ra?
Surface roughness Ra is a measure of the average height variation on a machined surface, affecting factors like fatigue life and sealing ability.
How does feed per tooth affect Ra in CNC milling?
A larger feed per tooth creates deeper scallops, increasing the surface roughness Ra.
What role does tool corner radius play in reducing Ra?
A larger tool corner radius smooths the peaks on the surface, effectively reducing the overall roughness Ra.
Can you explain the relationship between Ra and functional performance?
Surface roughness Ra directly influences functional performance by affecting factors such as fatigue life, sealing ability, and aesthetic quality.
How do I input values for feed per tooth and tool corner radius in the calculator?
Enter the specific values for feed per tooth (f) and tool corner radius (r) into their respective fields in the calculator to compute Ra.
What is the standard relationship used in the calculator for Ra?
The calculator uses a standard formula that relates Ra to the feed per tooth and the tool’s corner radius.
Why is it important to consider surface roughness Ra in CNC milling?
Considering surface roughness Ra is crucial because it impacts the functional performance, durability, and appearance of the machined parts.
Results are for informational purposes only and do not constitute professional advice.