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Author Topic: Required spindle power  (Read 2918 times)

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Offline Sweep

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Required spindle power
« on: September 28, 2010, 02:59:41 PM »
Does anyone know of a program that will advise the required spindle power /torque needed for a specific set of cutting parameters?
For example, 10mm milling cutter, cutting a slot (10mm wide), 5mm deep, when using, say, 1100rpm, 90mm/min feed and cutting mild carbon steel?
I only have 0.75kW (1hp) spindle motor so would like to make sure i'm well within the motor's performance when writing programming the machine. obviously a stall situation would not just stall the spindle but all my axis steppers as well - not good.

...Sweep

Offline RICH

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Re: Required spindle power
« Reply #1 on: September 28, 2010, 05:07:19 PM »
Kennametal has one on their site if memory is correct.
The Society of Manufacturing Engineers has done studies over the years and so did Cincinnati Millicron ( out of buisness now ).
There are also a few other sites as well. I have done it manualy by finding the shear area and  then finding the generated force. You need to make some assumptions ( like i used the mean average of ultimate tensile / yield / and shear stress  for a material ).
HP=FV/33000  where F=#   V=ft/min ( spindle) then consider motor efficiency , mechanical reducing into it. Just be practical and conservative if applying the results as there are variables which just can't be calculated and are factored based on testing and practical experience over time.

Additionaly there are programs that will caculate required torque, acceleration required  for a given axis based on machine / motor / etc  parameters and you can account for the metal cutting forces . Danier Motion or Superior Electric come to mind for a program. They are different for steppers and servos and you really should have a torque curve for the motor.

Above all .........garbage in =garbage out  :D

RICH

« Last Edit: September 28, 2010, 05:15:38 PM by RICH »
Re: Required spindle power
« Reply #2 on: September 30, 2010, 11:09:08 AM »
Try the G-Wizard CNC Calculator

http://www.cnccookbook.com/CCGWizard.html

Offline Sweep

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Re: Required spindle power
« Reply #3 on: September 30, 2010, 03:12:45 PM »
Thanks for the replies.
I will check out Kennemetal site to see what I can find and also have a play about with the CNC cookbook stuff, though the frontpage doesn't mention absorbed power.
i have fitted an ammeter to my machine panel that monitors supply current to the motor so if all else fails I can make some swarf doing some practical experiments.

...Sweep

Offline Sweep

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Re: Required spindle power
« Reply #4 on: October 18, 2010, 12:32:41 PM »
To follow up on my own post, I have found the site on the attached link that seems to work out power requirements though I haven't tried it out yet.

...Sweep

http://www.mapal.us/calculators/milling/CalculatorMilling.htm
Re: Required spindle power
« Reply #5 on: October 18, 2010, 10:22:35 PM »
Spindle power can be estimated as follows:

Power = MRR * PowerFactor

where:
    MRR = Material Removal Rate in cu. in./minute -> calculate as CutWidth * CutDepth * FeedRate
    PowerFactor = 0.2 for Aluminum, 0.9 for mild steel

Regards,
Ray L.
Regards,
Ray L.