Calculating Horsepower Requirement

[TheePres]

What formula do you all use to calculate horsepower requirement on insert cutter?

On MSOnline i found a formula, but it seems way off.

Says:

Calculate Metal removal rate

ipm x woc x doc = mrr

Then:

mrr x 0.25(alum hp-unit)= HP

So:

150ipm x 1.25woc x 0.15doc = 28.125

28.125 x .25 = 7hp

But these numbers using an Ingersoll aluminator has my machine at a 90% load.

[specv]

ipm x woc x doc = mrr

MMR/"K"FACTOR

 

ALUMINUM "K" FACTOR 6.25-3.3

 

That seems right to me.

I would run that cutter .300 deep

 

what kind of machine is it?

[YoDoug®]

quote:

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But these numbers using an Ingersoll aluminator has my machine at a 90% load.

---

That may be accurate. Ther are many factors that can affect the real HP you can cut with. The age of machine and RPM for example can have a big affect on usable HP.

 

What is the machine rated for HP?

[Guest CNC Apps Guy 1]

Don't forget it takes Horsepower to MAINTAIN speed even at a Zero Load.

[specv]

Right, and you have to look @ the horsepower curve, peak HP is only @ a given RPM

[TheePres]

This is a 40-taper "VIPER", rated at 25HP, will have Viper send me over a hp chart

Boss: "we need to cut run time"

Me: "get me a REAL machine"

Same argument day in and day out.

[crazy^millman]

We have a 50 taper Viper and I was pulling 200% spindle load on a 3" facemill .15 D.O.C x 6000 rpm x 300 ipm and that was a 10 flute High Shear Facemill. I had to back it down to .075 depth of cut and was still pulling 85% spindle load. The machine says it is 25hp but I figured I was only using about 18.75 HP. I would think what you are doing it should be able to handle that with no problem.

 

HTH

[chowquoe^]

TheePres you got mail

[Colin Gilchrist]

Don't forget that you also need to know what kind of Torque you have as well. The 25 HP rating would be the peak value which is usually near the machine's max RPM. It also has a lot to do with the physical setup. Is it a geared head, belt driven, or vector drive? what speeds/feeds are you running and what are the specs of your tool?

 

For a Haas VF-4 I used to run I was able to get a very valuable horsepower and torque curve chart that showed both torque and HP over the entire RPM range. It had 25 HP at 12,000 RPM and less than 10 HP at 1500 RPM.

[Craig Madsen from CM3D]

Look at the manual for your machine, then find the torque and horsepower curves.

 

On a machine I have a manual for, full power is available from 3600 to 7900 rpm (7.5hp).

 

From 800 to 3600 rpm the curve is liner from 1.8hp to 7.5hp. From 7900 to 15000 the power moves from 7.5hp to 2.8hp.

 

There is every possiblity that the machine you have may not have the power you think you have at the rpm you have programmed.

 

Power factor I use for aluminum: 4.5 cu/in per minute per horsepower. Work to what your machine has as a peak horsepower/Torque curve. It will never be at Maximum RPM. (Plus, your machine will perform better).

[Guest CNC Apps Guy 1]

HOw long are you at 200%??? If you're only going to be there continuous for a few minutes... may be worthwhile to leave it there. It would go a long awy toward showing the boss you're pushin' it hard.

[crazy^millman]

It would have been about 30 minutes at 200% so I just ran it at 95% for 1 hour. It was only 12 parts so it only cost me 6 hours. Saying that as PC as I can.

[TheePres]

In the next coming weeks our shop will be getting more alum. than building can fit, and all jobs are 7075 hog-outs. This Aluminator cutter was my 1st attempt at using insert cutters, and must admit it has impressed me.

Someone here mentioned "I would run that cutter at .300 deep", Could you tell me what machine could handle that cut?.

We will be ordering a couple more machines this week and would like all your input on what to look for. Machine must have capabilities of handling this type of cutter day-in and day-out, so was leaning towards a 50-taper gear head. But must also do 3-D finish work in the 200-300ipm range.

[crazy^millman]

Makino, Kitamura, Mori-Seiki, Toyota, Mazak, anything with a 40 hp or greater and 50 taper is going to be your best bet. Toyota has a 50 taper with over 10,000 rpm capability. You can get a 40 taper with 20,000 to higher rpms with capabilities of 600 to 800 ipm to offset not having a 50 taper.

 

HTH

[specv]

We have A66 makino's (30hp) and A77 makino's(40hp) and they would both handle that cut very easliy. with our A77 we run a 4 inch facemill @.300 deep full diameter 5500rpm 100ipm. We are going to try the aluminator, right now the sandvik coromill century works very well for us.

[specv]

oops double post