Mazak V5 retrofit spindle speed limit

I have a V5 VMC been around a few years, considering a retrofit on it.
The DC Spindle is only 5HP and 4500 RPM
which is a bit lean and slow for todays tooling.
To make it a worth while project, I think it needs to go to at least 10HP maybe 15 if a motor will fit in there, and 6000 RPM.

So my question is, before doing the 'try & see' test, would the spindle bearings self destruct at 5000 or 6000 if the orig. limit was 4500?? Provided they are in good shape to begin with.
I also suppose back then (1980) they didn't intend the spindle to run -at- 4500 for hours at a time.
Speed & HP is a major issue in retrofitting older iron.

dan k

Dan,
What kind of spindle and housing does it have? Is it oil splash, oil pumped or greased bearings?

It is going to have to dump the heat somewhere. It could be a lot of work to engineer in some method of cooling the spindle.

On my old Shizouka knee mill with regular quill and grease packed bearings, I was getting a lot of heat buildup running it at 3600 rpm for an hour. I changed the bearings over to a hybrid ceramic ball/steel race sets, ultra precision, of course. It was decently cool running after that, and I ran it for as much as 12 hours at a time at about 4000 rpm after that. I kept a fan blowing air at the head, and at whatever amount of the quill was extended. The machine was not working hard at the time, or I expect the temperature rise would still have given some grief.

That is one thing I like about the Haas I am using now: it keeps itself pretty cool. I run it full out at 7500 rpm for a few hours. I can still pop the tool out and feel inside the spindle and its just barely warm.

I'm thinking it's greased bearings.

dk

Most of the better tool builders used spindle bearings that were rated at least 20 % higher than the maximum spindle speed of the machine.
I would not recommend increasing the spindle speed with the existing bearings. As Hu stated, the problem is friction heat. Even with the new ceramic bearings, machine builders are putting external cooling devices on VMC,s. Some earlier VMC's even ran coolant through the head to cool the bearings and that was at 7500 RPM. Older machines were simply not designed for the higher speeds, just like you can't convert an older square way heavy machine with new servos to try to get 1200 I.P.M. cutting speeds.
AL

Hu.....
What kind of bearings in the Haas?
What kind of spindle cooling?

Thanks.

dan k

Dan,

I've never delved into the Haas yet to see. I do not know what kind of bearings it has.

I believe that the coolant circulates through a small heat exchanger on top of the spindle housing, and a fan forces air down to cool it. I haven't dug down any further yet to see if there is more to it.

They do use some kind of oil injection system to lubricate the spindle, so I am told, so that keeps the "thermal stirring" aspect to a minimum, because there is no heavy greasepack for the bearings to churn.

I believe that the coolant circulates through a small heat exchanger on top of the spindle housing, and a fan forces air down to cool it. I haven't dug down any further yet to see if there is more to it.

Click to expand...

I'd sure be curious to see how its set up.

dk