High speed machining (or, “How we play while making parts”)

Now that we’ve completed the chassis and are moving onto some of the other rover components, I’ve had the opportunity to take on some components which present a bit more variety in the manufacturing arena.  One of my research interests lies in high-speed and high-productivity machining technology, and I’ve gotten the opportunity to try out some new tools and toolpaths on some of the rover’s larger components.  I’ve always been a big fan of Lakeshore Carbide’s variable flute endmills for aluminum, particularly their 3 flute ZrN coated models.  They can take aggressive feedrates at the full 12000 rpm maximum of our Haas VF-4.  The coating holds up well, and the razor sharp flutes leave an awesome surface finish.  The variable flute and 3-tooth design combats vibration, even in thin wall and floor situations.  With this part, I went for a 3/8″ tool and a troichoidal peel milling toolpath, with a full depth cut 7/8″ deep, 0.040″ radial engagement, and 240 inches per minute feedrate (linear equivalent 300 ipm).  An air blast was used for cooling and chip evacuation.  The total cycle time was 6 minutes with a fully engaged metal removal rate of nearly 7 cubic inches per minute during the roughing operation.  Video to be posted shortly.