New DMG 65 Monoblock Spindle Options

[crossthread82]

Hi all,

I'm currently getting a quote for a new 65 monoblock and I'm undecided on what spindle to get. We are a job shop that cuts mostly aluminum and plastic but do get the occasional 1018 or 303 part. Generally the harder material parts aren't all that big. I'm looking at the HSK 20K spindle or the HSK 30K spindle. I've heard that the 30k spindles can be kind of fragile. But does the extra HP and speed make up for it since we mostly cut 6061?

Does anybody have a DMG with the HSK63a 30K spindle?

Appreciate any input.

 

[Milling man]

Hi all,

I'm currently getting a quote for a new 65 monoblock and I'm undecided on what spindle to get. We are a job shop that cuts mostly aluminum and plastic but do get the occasional 1018 or 303 part. Generally the harder material parts aren't all that big. I'm looking at the HSK 20K spindle or the HSK 30K spindle. I've heard that the 30k spindles can be kind of fragile. But does the extra HP and speed make up for it since we mostly cut 6061?

Does anybody have a DMG with the HSK63a 30K spindle?

Appreciate any input.

DMG didn't tell you the inside diameter of the spindle bearing? This is a fairly common machine parameter to get an idea of how stiff the spindle will be.
In principle, VERY-VERY inaccurate, we can say that with the same spindle power, the one with 2 times more revolutions allows 2 times less cutting force.
I worked on a Mori-Seiki machine (they teamed up with DMG, so you can probably say that this is up-to-date data) with a 24k spindle. I can't say anything bad, we mainly processed hardened steels - molds, dies and the like. Of course, with such a spindle, we mainly finished finishing with small cutters, but a 63mm face mill was not a very rare tool either.

 

[boosted]

Why a DMU65 instead of a DMU75? DMU65's are only special order now.

The 20k speedmaster spindle is a workhorse. In a job shop it is unbeatable due to a really wide powerband and ability to take a beating.

The 30k is somewhat more productive, but not nearly as versatile.

Hard to make that call without knowing your products. At 30k on a larger spindle, balancing etc... becomes a constant issue. Usually not worth the hassle unless you have really robust offline presetting and balancing, and are making parts where it can run flat out for long periods of time, but still use the power of a larger taper. So typically the 30k HSK63 and HSK100 are reserved to larger aerospace shops.

 

[crossthread82]

Why a DMU65 instead of a DMU75? DMU65's are only special order now.

The 20k speedmaster spindle is a workhorse. In a job shop it is unbeatable due to a really wide powerband and ability to take a beating.

The 30k is somewhat more productive, but not nearly as versatile.

Hard to make that call without knowing your products. At 30k on a larger spindle, balancing etc... becomes a constant issue. Usually not worth the hassle unless you have really robust offline presetting and balancing, and are making parts where it can run flat out for long periods of time. So typically reserved to large aerospace shops.

I miss spoke the quote is for a DMU 75, I was thinking of our current 65. We do mostly aluminum, parts range from tiny to about a foot cubed. We generally end up finishing with tools under .250" so the higher rpm is appealing.

In terms of balance we primarily run rego power grip holders or schunk hydros which both are balanced G2.5 or better at 25k. A rep from rego said I should be fine running their standard holder at 30k.

Below is the power curve of both:

 

[Vancbiker]

You should ask the machine builder for their position on balancing for a 30k spindle. Most will say you should balance the assembly before running high speed. I’d pay more attention to the machine builder than a tooling sales person.

 

[boosted]

No way I would run a 30k spindle without balancing tool holder assemblies offline. DMG MORI will say the same. The balancing of the holder is completely compromised once you stick a tool in it. This isn't as big a deal for smaller spindles, since they have way less rotating mass.

Also, if you already have an 18k or 20k spindle, it seems really foolish to have an orphaned high speed setup with different performance. Buy spindle speeders for finishing if is that big of a deal. The ROI for an 80k air turbine is way easier than for a 30k spindle.

 

[crossthread82]

No way I would run a 30k spindle without balancing tool holder assemblies offline. DMG MORI will say the same. The balancing of the holder is completely compromised once you stick a tool in it. This isn't as big a deal for smaller spindles, since they have way less rotating mass.

Also, if you already have an 18k or 20k spindle, it seems really foolish to have an orphaned high speed setup with different performance. Buy spindle speeders for finishing if is that big of a deal. The ROI for an 80k air turbine is way easier than for a 30k spindle.

That's a valid point. I've never looked at the air spindles for hsk machines because of their really long gauge length. But as I figured going 30k is more of a want than a need and the drawbacks of going with it are likely to out weigh the gains. Still would be nice to murder some aluminum like its a mag3 but I'll just have to keep dreaming or start watching Titan

 

[fmari --MariTool-]

For HSk63 at 30,000 rpms you really should have a balancer. Shrink or hydraulic holders with 1/4" tooling you can get away without balancing at every tool change. But anything larger and anything with a collet nut you will need to balance every time a tool is changed.

 

[Vancbiker]

.......Still would be nice to murder some aluminum like its a mag3......

It won't. That spindle is lacking about 100HP to a MAG1 let alone a MAG3.

 

[crossthread82]

It won't. That spindle is lacking about 100HP to a MAG1 let alone a MAG3.

I know... I was only joking. Its still pretty impressive for the footprint of the machine.

 

[crossthread82]

For HSk63 at 30,000 rpms you really should have a balancer. Shrink or hydraulic holders with 1/4" tooling you can get away without balancing at every tool change. But anything larger and anything with a collet nut you will need to balance every time a tool is changed.

Understood. I've seen holders with balancing rings on them. It would be pretty trick if somebody came up with a floating ring in the holder that self balance when spun up to speed. Not sure if that's even possible.