The Impact of CNC Machining Surface Roughness on Magnesium Alloy

The surface roughness of magnesium alloy products after CNC machining has a significant impact on the quality of abrasion. Generally, a smooth surface provides better uniformity and density for coatings compared to a rough surface.

Abrasion on a rough surface is difficult to achieve uniformly and is prone to defects. Therefore, for surface treatment, rough surfaces should first be leveled to achieve a certain degree of smoothness before proceeding with pre-treatment and then surface treatment.

Surface roughness is a technique used to measure the smoothness of a product. It indicates the state of the processed surface of the product, with panels and body covers exhibiting different appearances of smoothness or roughness.

Additionally, there are factors that can affect appearance, texture, and mechanical properties, such as friction, fatigue behavior, and light reflection. In this study, Ra and Rz were used to analyze the surface roughness of each sample.

Surface roughness and layer factors are strongly dependent on cutting parameters, tool geometry, and the resulting machining forces. During each machining process, cutting speed has a significant impact on surface finish quality.

Researchers found that increasing cutting speed improved surface finish, reducing surface roughness while simultaneously enhancing machinability.

For all feed rates, the optimal cutting speed for achieving the minimum average roughness was found to be 200 m/min. The minimum value was observed at the highest speed, i.e., 500 m/min and feed rate of 0.10 mm/rev.

However, feed rate is more crucial in determining the surface roughness of the processed product. Increasing feed rate leads to a decrease in surface finish quality and an increase in surface roughness. In end milling, it is recommended to use high cutting speeds and low feed rates (0.01 mm per tooth) to achieve better surface finish within a specific testing range.

The lowest feed rate (0.05 mm/rev) and highest cutting speed bring the best surface roughness values.