Machining exhaust flanges

[pauls]

I'm machining exhaust flanges out of 304 stainless steel. The material is 1/2" thick. I'm using a 1/2" carbide cutter. There are four 2x1.75" ovals for the exhaust ports. I'm using a pocketing function but the mill seems to bog down when plunging into the pocket. I'm using a depth of .0625 and a feed rate of F.5. It is really hard on the cutters. Since the flange is being cut out of 3x14" flat plate the mill is nearly always cutting a full width 1/2". Any suggestions how I can do this more efficiently? I haven't tried using a roughing mill.
Paul

[Ken_Shea]

What type of cutter / # Flutes ?

RPM ?

Horse power ?

is that .5 ipm feed or 5ipm

.

[psychomill]

+1 to Ken...

Also try drilling a pilot hole first or ramping the cutter.

But, we do need more info as Ken states.

[vladdy]

If you are doing quite a few of these, it would probably be worthwhile to make a simple jig, where the flange would be bolted down through it's normal attachment holes, and have a space underneath..even something as simple as small cut off pieces of pipe with the flange bolted through to a 'master' plate underneath....
With a pre-drilled [large] pilot hole the cutter would only be working the sides, a nicer cut as well as a little more rigid [as far as the bit is concerned]

I assume these are header flanges [ marine?] so the quality of the pilot [or rough cut] wouln't matter much, just the final, especially 'outside' visible cut..??

added bonus would be that the chips would drop through, easier viewing ..
just a suggestion..

enjoy..

[skippy]

Lots of time and lots of bother! How much can they possibly cost to get laser or plasma cut? (take into account cutter wear/breakage) No matter whether you mill or laser cut, you'll probably still have to do clean up and/or port matching with a die grinder after the welding process. Just my 2 cents worth
Skippy

[DareBee]

0.5 feedrate does seem extremely slow. I would use a helical plunge to start and use A LOT of COOLANT. Tialn coated carbide would be best and I would start at 2000RPM @ 16 IPM.

[pauls]

I'm probably pushing the machine beyond its capabilities. Its a Industrial Hobbies Grizzly Square Mill conversion at 2HP. I'm using 4flute,carbide center cut mills at 900 rpms with flooding coolant and the plunge feed rate is .5ipm an the transverse rate is 8ipm. Any faster and I get vibration. Appreciate the input.

[Ken_Shea]

You may be correct in that you are pushing your machine but the several suggestions already given are needed and worth trying.

1) Carbide needs a chip load and .5 is not going to provide that.
2) You could probably double the RPM and still be safe but some specs I am looking at say about 1400rpm.
3) Decrease your DOC to .030, perhaps even less but with a corresponding feed increase.
4) As mentioned try a helix instead of plunge if at all possible, I hate plunging and avoid it where ever I can, it never seems to be smooth always the heaviest in vibration.
5) Examine the tip closely on your cutter, could be it is trashed, I save those for profiling
6) I like vladdy's idea.

[pauls]

I'll try those suggestions and let you know how it worked out. Thanks to all.