fly cutter vs indexable face mill

[777mechanic]

i just finished a job for a friend and i had to mill a piece from 1.00 down to a 1/2 , so i used the a three wing indexable face mill . the finish wasn't that nice , and or machinist at work said to use a fly cutter for a better fiinish , would everyone please post comments on the best way to get a flat surface and which type of cutters they use to accomplish this task the material was 8"x 32 " aluminum stock.

 

[old cone]

I use the indexable cutters and can get a good finish in Al. I take a light finish cut and feed according to the finish desired. I find that some of the import indexable cutters seem not to be made to close tolerances and one cutter seems to bear most of the load. I have used Kerosine brushed on for a good finish. Most plate is extruded 6061 and will tear with dull cutters or wrong coolant/cutting fluid . Notice I said brushed on. Or squirt with WD 40. Mill head must be swept in to avoid mismatch.

 

[nickmckinney]

8" x 32" in aluminum is about the same as surfacing a large straight 6 cylinder head. With a mill setup most I know use either a 10" face mill:



Or a CBN/PCD single puck system like this where the disc has to be massive in weight and balanced perfect:




I do enough of these cuts that I picked up a dedicated machine that also has a segmented stone option:

 

[Andre]

Depends on what mill you have. Smaller mills don't like flycutters much, I have a BP M head and the old bearings mag at me when flycutting. Face mills are better for rough cuts, and for finish cuts I like flycutting.

Keep in mind, with flycutting you have to grind your own toolbit. With face mills, you do not.

 

[DMS]

General consensus is that fly cutters give a better surface finish than all but the best face mills. This is for the reason that oldcone states, in order for a face mill to do as well, all the cutters have to be exactly even. For a fly cutter, there is only one cutter so there is no adjustment.

Tormach has a flycutter called the "Superfly" that uses the same square inserts used by shell mills. They make a pretty good case for using fly cutters on machines under 3HP because you just can generate enough power on machines that size to make use of more than one insert.

I would also add, that 1/2" is a lot of material, if possible, a saw is always the fastest way to remove material. If you have any more to do, maybe see about sawing about 0.300 off, and finishing up the rest with a fly cutter. Should save you a lot of time.

I will also add that cutting fluid makes a big difference on surface finish on aluminum. A little spritz of wd40, or some Coolmist 77 prevents galling, and built up edge. Even better is a fogbuster type setup that will cool, distribute fluid, and remove chips. Although, for a fly cutter chip removal is generally not a problem; most of my chips end up on the other side of the shop when using the fly cutter.

 

[Jackalope]

General consensus is that fly cutters give a better surface finish than all but the best face mills. This is for the reason that oldcone states, in order for a face mill to do as well, all the cutters have to be exactly even. For a fly cutter, there is only one cutter so there is no adjustment.

Tormach has a flycutter called the "Superfly" that uses the same square inserts used by shell mills. They make a pretty good case for using fly cutters on machines under 3HP because you just can generate enough power on machines that size to make use of more than one insert.

I would also add, that 1/2" is a lot of material, if possible, a saw is always the fastest way to remove material. If you have any more to do, maybe see about sawing about 0.300 off, and finishing up the rest with a fly cutter. Should save you a lot of time.

I will also add that cutting fluid makes a big difference on surface finish on aluminum. A little spritz of wd40, or some Coolmist 77 prevents galling, and built up edge. Even better is a fogbuster type setup that will cool, distribute fluid, and remove chips. Although, for a fly cutter chip removal is generally not a problem; most of my chips end up on the other side of the shop when using the fly cutter.

That's the reason they are called fly cutters

 

[777mechanic]

i have a 1 1/2 hp vs bp. mill and the shell mill is a 2" knock off brand , i'll have to start researching a good fly cutter . and as for the bandsaw i have a delta 20" setup for woodworking so i need to get some pulleys to reduce the speed . also how do you deal with the flying chips as my arms and neck are quite burnt after this project . no complaints though had a blast doing it for a friend .