CNC Machining Magnesium Alloy Parts: What Most Shops Learn Too Late
For many machinists, magnesium looks easy because it cuts with very low resistance. Our experience has been the opposite. The biggest challenge is not tool wear-it is heat control and chip management.
Several years ago, we machined a batch of AZ31B electronic housings with deep pockets and thin walls. The first setup used parameters similar to aluminum. Surface finish was acceptable, but fine chips accumulated around the cutter, causing local heating and heavy burrs at pocket exits. After reducing spindle speed by about 20%, increasing feed slightly, and adding compressed-air chip evacuation with MQL, burrs became much easier to remove and tool life improved noticeably. The machining time changed very little, but secondary deburring dropped enough to save nearly 25 minutes per batch.
One lesson we still follow is simple: magnesium rewards stable chip evacuation more than aggressive spindle speed. Sharp carbide tools, positive rake geometry, and consistent chip load matter far more than chasing the highest RPM.
Customers often focus on machining cost, yet dimensional stability, surface integrity, and safe chip handling usually determine the real production cost. Choosing the correct machining strategy at the process planning stage is often more valuable than selecting a faster CNC machine.