Most experienced manual machinists know that if you want the best finish, you’ve got to whip out the fly cutter. Now many CNC machinists use face mills for finishing, the best machinists know there’s no way to beat the finish from a CNC fly cutter.
CNC Face Mill versus Fly Cutter
Every manual machinist knows the finest aluminum finish comes from a fly cutter with a diamond insert. CNC machinists should know this too. Face mills run at a high speeds. But when it comes to fab finish, you want slow speeds for that spectacular brushed finish. Plus, if a face mill is going to provide a fine finish you’ve got to remove all cutters except one. In that case, all you did was turn your mill into a fly cutter. This kind of face mill set-up won’t quickly remove material, but you’ll score a pretty fair surface finish.
A fly cutter does jobs your face mill can’t. See this link for a fly cutter resurfacing a table saw table. Only a CNC fly cutter is going to get that job done right.
Why use a face mill when a fly cutter is clearly the best tool?
Always Use These CNC Fly Cutter Machining Tips
Use these tips and finish even the toughest materials like titanium or stainless steel flawlessly.
Always Watch Feeds and Speeds. Apply the right feeds and speeds to the machine and material and you can do anything. Difficult materials are only described as difficult because of their small machinable range. Good software accounts for all variables. Make sure yours does.
Always Use Coolant. Your material may just machine better if you apply fluid or your material may require fluid. Use coolant no matter the situation. Always use fluid, even if it is a mist. Stainless resists hardening better and aluminum chips won’t weld to the cutter. Prevent heat build-up in titanium by generously applying coolant.
Always Clear the Chips. Whether you are using a liquid coolant or an air mist, make sure you keep chips clear. Recutting chips that aren’t cleared just makes the job harder for your tool. No matter the method, clear chips as fast as they are made.
Make sure you use the right cutter for the job. Sierra American makes 1½”, 2”, and 2 ½” diameter fly cutters. Alloy screws reduce chatter. High RPMs aren’t a problem. If your feed and speed calculations say “let’er rip” the Sierra American flycutter says “okay”. Get a balanced tool when you get Sierra American Multi-systems. If your tool pusher doesn’t have it, ask them to order it.