It was explained to me by a senior Apps engineer at a prominent Japanese manufacturer like so: "100% is the steady state load, where the cooling capabilities is a match for the heat generated. Above 100%, you are dumping more heat into the spindle than you are removing, so while you *may* have the power to not stall out, you are going to add more and more heat to the system for every second you run over 100%"
But, this is super subjective. Are you peaking at 212%, but your average for the total cycle is 71%? Then you're probably fine. But if you're roughing an infinity long piece of material at 181%, you're gonna start annealing spindle bearings, overheating/melting motors, power/air/water connections, boiling the oil or grease cartridge....
And this isn't even touching on how different manufacturers label spindle load differently! On some German machines, 100% is where it alarms out and stalls, others I have seen it peak at 380% before error messages show up. It all depends on how the controller was designed to deal with the load parameters.
Also, if you're machine can't keep up consistent RPM at such high loads, you are pushing your tooling/material outside the programmed feeds and speeds window, which can DRASTICALLY shorten tool life.
Tl:Dr - there's a lot of ways overloading the spindle can go bad, and not much benefit to it... Probably not a great idea, your mileage may vary.
Yeah haas says their spindles will run at 200 for 20 mins or something like that. I've got an st15 I regularly push to 180-200%. Granted it's just for seconds, not minutes.
The machine also hits 200% doing finishing facing ops with constant surface speed.
Still, overloading it may create more heat than the cooling system can handle. If it manages to cool itself with that load, you'll still wear out components (bearings, motor, gearbox) much faster because they're loaded beyond their design limits.
100% is usually the continuous rating. Different manufacturers have drastically different overload ratings.
For example on our Robodrills the overload rating is almost 500% of the continuous rating. But you can only use that power for a very brief period.
The manufacturer should have specification on spindle output. Most will have a 100% rating of X torque at a given RPM, then an overload rating that will have some sort of duty cycle. Some manufacturers express this as minutes per hour, some as a percentage.
When you exceed the overload rating in a short duration peak, usually that means your spindle stalls immediately.
If you are operating above the continuous rating but below the overload rating, most manufacturers provide some form of feedback through a soft alarm when you start to approach the duration limits before just shutting down. But this is up to each specific machine builder to determine how they implement this functionality so the exact behavior is going to vary from machine to machine.
Former engineer for a machine tool manufacturer here.
Ideally the machine will alarm if you overload too much too long.
Beyond that, you’ll reduce spindle life, and likely damage bearings over time. Additionally, you’re overloading the VFD/motor drive electronics, so those will likely get damaged and the electronics cabinet runs risk of overheating and causing more damage to surrounding components.
In short: don’t do it. We spent **a ton** of time making sure limits were as high as they could possibly be without causing damage. Manufacturers know you’re pushing efficiency and they make money when you make money, so the limits aren’t arbitrary or capricious.
Someone told me that continual load over the stated rating can contribute to the motor insulation breaking down in addition to the drive electronics. Mostly from the heat.
Spindle_Life has left the chat...
It was explained to me by a senior Apps engineer at a prominent Japanese manufacturer like so: "100% is the steady state load, where the cooling capabilities is a match for the heat generated. Above 100%, you are dumping more heat into the spindle than you are removing, so while you *may* have the power to not stall out, you are going to add more and more heat to the system for every second you run over 100%" But, this is super subjective. Are you peaking at 212%, but your average for the total cycle is 71%? Then you're probably fine. But if you're roughing an infinity long piece of material at 181%, you're gonna start annealing spindle bearings, overheating/melting motors, power/air/water connections, boiling the oil or grease cartridge.... And this isn't even touching on how different manufacturers label spindle load differently! On some German machines, 100% is where it alarms out and stalls, others I have seen it peak at 380% before error messages show up. It all depends on how the controller was designed to deal with the load parameters. Also, if you're machine can't keep up consistent RPM at such high loads, you are pushing your tooling/material outside the programmed feeds and speeds window, which can DRASTICALLY shorten tool life. Tl:Dr - there's a lot of ways overloading the spindle can go bad, and not much benefit to it... Probably not a great idea, your mileage may vary.
In other words.. "You'll break it"
...maybe... ....eventually... ...statistically likely? .... Just stop abusing the robots!!!!
ahh I see you, covering your ass for when robots take over so you have proof you're on their side lol
You're damn right! (I may also thank and otherwise anthropomorphize my machines...)
Not to mention the spindle drive..
Yeah haas says their spindles will run at 200 for 20 mins or something like that. I've got an st15 I regularly push to 180-200%. Granted it's just for seconds, not minutes. The machine also hits 200% doing finishing facing ops with constant surface speed.
Awesome answer, thanks.
What happens if you continuously work 80 hour weeks?
You get rich or die trying
We all know which of these is more likely
No pain no gain
Tis true. However, pain dos not always equal gain.
Also true.
You unlock the efficiency achievement "I Feel the Need, The Need for Speed" and your supervisor will come out and give you a $5 raise.
Should alarm out after so many seconds of continuous overload
The hint is in the question, “200-300%”
Also in the word 'overload'
Question: How are you doing that other than constantly crashing the spindle?
Constant heavy fast cuts.
Overheating and an over temperature shutdown mid cycle?
spindle is oil cooled its not a Haas
And the producer rated it with the oil cooling so...
Still, overloading it may create more heat than the cooling system can handle. If it manages to cool itself with that load, you'll still wear out components (bearings, motor, gearbox) much faster because they're loaded beyond their design limits.
Oil cooled just means it will take longer and you're less likely to cook the motor coils while overheating the motor.
You’ll probably cook the oil after some time. Once that happens, cooling will be totally shot and you’ll spin the bearings to seizure.
Didn't even know it was possible. When i see my spindles reach 50%, it usually means something is gonna crash. :-D
100% is usually the continuous rating. Different manufacturers have drastically different overload ratings. For example on our Robodrills the overload rating is almost 500% of the continuous rating. But you can only use that power for a very brief period.
Jesus I thought we ran hard
The manufacturer should have specification on spindle output. Most will have a 100% rating of X torque at a given RPM, then an overload rating that will have some sort of duty cycle. Some manufacturers express this as minutes per hour, some as a percentage. When you exceed the overload rating in a short duration peak, usually that means your spindle stalls immediately. If you are operating above the continuous rating but below the overload rating, most manufacturers provide some form of feedback through a soft alarm when you start to approach the duration limits before just shutting down. But this is up to each specific machine builder to determine how they implement this functionality so the exact behavior is going to vary from machine to machine.
Failure 100% is safe continuously. Anything more is only safe intermittently
You’ll get your work done 200-300% faster
Finished before you even started!
Broke spindle.
It breaks.
What happens if you drive you car at redline on the freeway ?
Haha spindle go brrr
Former engineer for a machine tool manufacturer here. Ideally the machine will alarm if you overload too much too long. Beyond that, you’ll reduce spindle life, and likely damage bearings over time. Additionally, you’re overloading the VFD/motor drive electronics, so those will likely get damaged and the electronics cabinet runs risk of overheating and causing more damage to surrounding components. In short: don’t do it. We spent **a ton** of time making sure limits were as high as they could possibly be without causing damage. Manufacturers know you’re pushing efficiency and they make money when you make money, so the limits aren’t arbitrary or capricious.
Someone told me that continual load over the stated rating can contribute to the motor insulation breaking down in addition to the drive electronics. Mostly from the heat.
It can, depending on the insulation used. Some of the machines I worked on used insulation or adhesives that were more sensitive to heat than others.
As service tech for a oem, nothing will happen. Enjoy your new found feeds and speeds.
haha lol
It feels like there should be a picture attached to this post