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Pardon my ignorance, but I've been thrown into the fire, so to speak. I need to machine a pocket in 1018 material. The pocket is 1.3125 deep, 1.5 wide and is 6" long. The machine is a 35 taper vertical CNC. I've got a 1" dia. insert mill with 2 inserts. I started the job with 1.0469 drill bit. I drilled 4 holes and then milled the pocket with a 1" roughing endmill. Then finished with the 1" insert mill.
I know my feeds and speeds are wrong. I don't have the SFM for the insert mill. Is it true that the 1.0469 bit should have the RPM 292 with a feed of F4. ?? Is the machine not good enough to machine at this SFM? Any HELP would be much appreciated.
Your end mills are too big in my opinion. The larger the tool the greater the surface contact. 1018 is an easy material to machine. I suggest a .5 inch solid carbide end mill. Start at 3000 rpm and a feed rate of 20 and bump up your feed from there. And use .2 depth of cut.
King Bob, Thanks for the insight. I'll try that in the morning. How bout' some feeds and speeds on the 1.0469 drill bit. Is this process how you would do it?
I have weak haas tm1 so if I need to drill a hole bigger than .25 I circle mill it. But if the drill is the only option I would spin it around 300 rpm and only feed at around 5 and peck Drill about .15 per peck. Bump up your feed until you get ribbons for shavings. Also drill a pilot hole at least .375. I am not sure what u are running but like I said my recomendations stem from having to constantly deal with the limitations of my machine.
Are you drilling for stock removal? If so I don't recomend it. When pocketing I use a helix style entry with a center cutting end mill. Fewer tool changes mean lower total run time.
Thanks for the help King Bob. Would this procedure be the most efficient for a production run of 1000 pieces? If not, will you provide me with some more knowledge?
I'm with Bob, drilling for stock removal is a waste, you're feeds and speeds for pocketing are going to be based on full engagement anyways, which you can't avoid.
I'll also say, your tool is too damn big, a 1/2" variflute will make better use of your HP, cut free-er (is that even a word?), and move more chips than I'm guessing you have the HP for.
As for ramping or drilling, well, if you already have a drill for another feature, it doesn't hurt, as long as its as big or close enough to the size of the endmill.
As for ramping, I'm all for that too, it does beat up the end of your endmill a bit more, but when done properly, half of your pocket is done by the time you get to depth. In your instance, I'd ramp the length of the pocket, swing around come back ramping the other way offset .450, (with a 1/2" endmill), by the time you get to depth, you're pocket is 2/3 done.
As for helical entries, I use 'em occasionally, but I'm not a fan. Say for instance you are using a 1/2" endmill and creating a 1" hole as your entry point, running a 3 degree ramp at the center of the tool, at the center of the 1", the tool is still plunging, while running a lesser ramp on the OD. I find it beats up the tool significantly more than a straight line ramp, and by the time you get to depth you still have the rest of the damn pocket to take out.
Send me a print I can program it for you so you can have an example for future projects. I just need to know the make and model of the machine.
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