Should i warm up the spindle

[samu]

I have a hardinge vmc 1000 8k spindle(almost always running at 8k rpm). Should i warm up the spindle before making chips?? Actualy i let it turn at 2500 rpm about 20 min before machining. Is it a wast of time?? Does it only add some run time on the spindle bearing?

[christinandavid]

Its not a waste of time if you intend to put significant load on the spindle. If you are taking light cuts that don't even register on the load meter you can probably get away with it.

You may want to write a warm-up program that gradually increases your spindle speed to the normal running speed over that twenty minute period - and if you feel that you should warm up the spindle you could kill two birds with one stone and warm up the other machine axes as well. We use our program (called with an M-code) to warm up the machine at the start of the day and wash it down at the end of the day (with auto shut-down). Works well.

DP

[machintek]

If it was my spindle, I would be doing the same thing.

George

[holbieone]

Originally Posted by samu I have a hardinge vmc 1000 8k spindle(almost always running at 8k rpm). Should i warm up the spindle before making chips?? Actualy i let it turn at 2500 rpm about 20 min before machining. Is it a wast of time?? Does it only add some run time on the spindle bearing?

you should warm up your spindle all the time

one reason is spindle growth do to heat , a cold spindle will cut a few tenths to a few thousands different than a warm spindle

another reason is the grease in the bearings , when cold the grease is thick and is push out of the bearing path , when warm the grease is liquid like oil and will flow back into the bearing path

[ImanCarrot]

Definately. Always warmup.

I wrote a prog for mine that warms up the spindle, and both axes on my lathe and my mill (they come on automaticaly in the morning).

Coldness is your enemy- a 100mm (4") iron rod will expand by 0.012mm (0.00047") at a temperature change of 10 deg C.

Your machine in the morning is essentialy a big lump of cold metal with cold oil inside it.

[M99 Dan]

Always, Always warm up. Just like before going on a long bike ride or jog. It gives the machine a chance to lubricate itself, steel to grow and settle and you can go and make yourself a pot of coffee while you wait. christinandavid has a good point. Start slow and work your way up. Warming up all of the axis is very beneficial as well. My Kitamuras won't even allow a job to run unless they have been warmed up. 20 minutes minimum @ 5000 rpm or they just alarm out.

Dan

[tacdriver]

So what is a good warmup routine? I've been doing 1K rpm for about 1/2 hour. No table motions, though. Machine is usually at about 45 to 50 deg. F most of the year.

Should I write a program to step up the rpms? Say, 500/1000/1500/2000/2500 so about every 5 minutes it bumps up a level?

I am more concerned with bearing life and being kind to the machine than 2/10,000 tolerances as most of our parts have tolerances that are easy on us.