CNC fly cutters are the best way to machine flat surfaces. They are easily sharpened. When it comes down to it, fly cutters are probably the most economical way to remove material on a mill. There’s no mystery behind the fly cutter, even though they frighten some machinists. It’s just basically a left-handed lathe tool.
Tips for using CNC Fly Cutters
Just like anything else you do in the machine shop, you must secure the work to the work table. A fly cutter with a ½” or 3/8” bit will cut aluminum without even trying. CNC fly cutters actually peels the material off the work without exerting much crushing action. So, fly cutters exert low stress on the machine.
For best results, set up so the cutter moves in a diameter larger than the width of the part. You should get a second cut from the back side of the cutter even if the spindle is perfectly square to the table.
Like any other job, protection is important. Long sleeve shirts and eye protection are a must. Those chips leaving the CNC fly cutter are hot and they won’t have time to cool before they hit your arms. Cut from right to left so the chips fly away from you.
Finishing with a Fly Cutter
No cutter finishes better than a fly cutter. Get the radius large enough and make one pass and you’ll have the finest finish available. Just follow these tips.
Evacuate Chips. It doesn’t matter whether you flood with air or coolant, just be sure to keep chips evacuated. If hot chips touch the work surface, the finish can be destroyed.
Keep RPMs High. You’ve got to get feeds and speeds right. It’s important to keep RPMs up. Think of it like this, if you can minimize the time the tool touches the material, you can minimize the chances of edge buildup. And less edge buildup means a smoother finish. Check your g-wizard software and check your setup twice.
Double Check the Geometry. After double checking your feeds and speeds, double check the geometry of your bit. Verify you’ve got the lead angle right. The higher the lead angle, the better the results. Check the nose radius too. You want a large chipload in relation to the radius of the cutting edge. That peels off chips cleanly. If instead, you have a large cutting edge radius to chipload ratio, the cutter can’t get under the chip. It won’t peel the chip off cleanly. What will happen is heat build-up. That’s not good for the work or the tool.
The best fly cutters make the best finishes. The best fly cutters are made by Sierra American Multi-Systems.
The large set screws keep the cutter stable, that means less chatter. They are completely balanced to run at the high RPMs you need for fly cutting.
Every CNC fly cutter is made in the USA. We support American manufacturing and American machinists. That’s why every CNC fly cutter is backed by a full 5 year warranty.
If you want quality, you’ve got to ask for Sierra American by name. A quality finish starts with a quality fly cutter from Sierra American.