Helical Entry help

[MotorCityMinion]

I need some help with this.

 

4140ph.

 

3/8 bullmill .03r. 4 flute Centercut Carbide.

 

320sfm / 3259 rpm / 108 ipm throughout the rest of the HST op.

 

Going to a depth of .70. from solid. Entry moves are set at 1/2 deg. , 45% min max rad. This produces a dia. of .337 at the center of the tool path (.712 actuall cut dia.) so I know no spikes will be left standing.

 

The depth per rev works out to be .0093. Is this too much or too little?

 

Here's where I need some help. Is the 45 deg. min max rad adequate or too large?

 

Entry feed rate. I was thinking 25% or 27 IPM. This will produce a chip per tooth of aprx. .002. Is this too heavy? Sounds like it might be, but I don't have experience with this so IDK.

 

Thanks in advance, MCM.

[K2csq7]

The window for feeds & speeds in 4140 PH is about the size of Lake Erie.

 

As for the ramping.... .7 is pretty deep, Your tool dealer will be able to tell you the optimal ramping angle for their end mill. Your .009 & 27 IPM sound close enough for me to hit go.

The BEST way to optimize your feeds & speeds requires you to break an endmill. If you have the time / material, bump up the ramping angle & feed until you get a chipped flute or 2, then back off a bit.

[Mr. Wizzard]

I helix ramp as large as possible, while avoiding a xxxx left at the bottom, like you are doing. The larger the bore, the better the chip evacuation. Like Keith says, don't be afraid to push it. Too light a cut on entry may dull up the endmill before you even get to the bottom and start cutting. If you can, pre-drill a pilot hole and plunge the endmill straight down, then start cutting.

[MotorCityMinion]

Thanks for the input.

 

.5 deg and 12ipm 1st piece, way too slow. No dwell option in this tool path so RPM's remain the same for now. Will bump up the feed incrementally. I'll pass on the break point theory for now as I already used that opportunity on another area of the part. -.-

 

My dealer is a middle man who uses tech support from India. Slim chance getting decent data from them in a timely fashion, if at all.

 

Thanks again.