Lyndex-nikken pull studs failing...

[?Mark]

A little heads up...

 

Had 3 (yes three !!!) cat 40 mori-seiki pull studs develop cracks. Only ones with a .125" shoulder thickness seem to be afected.

 

Got a bunch with a tooling package for a new mori vertical a year ago. Needless to say just replaced all of them just in case and with our money

 

Looks like they don't make them so thin anymore ( I wonder why... )

 

Thank God they didn't fail while running...

[Guest]

Thnaks for the heads up Mark

 

Everything here, well 95% is Lyndex.

 

I gotta do some checking.

[Hardmill]

Any chance theres a machine issue??

Ive seen too much pressure crack pull studs in the past.

 

 

PEACE

[?Mark]

Don't think so Steve.

All other pull studs are good (command with a .250 shoulder).

Lyndex changed the design and increased shoulder thickness from .125 to about .250".

I wonder why

 

IMHO they should freaking replace them all...

[Hardmill]

quote:

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IMHO they should freaking replace them all...

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You contact them yet ??

I think they should.

 

 

PEACE

[robk]

Thanks for the heads up Mark...

We're all Command, but for single replacement I usualy will purchase Lyndex so we have about 1/2 dozen floating around here.

The operator told me he just checked them and that they all look good.

Mark, did the ones that failed you have a coolant hole in them or were they solid? Or did it make no difference? I only have the ones with the coolant hole in them.

[?Mark]

Mori uses din holes (in a flange of a holder), so no, the pull studs are solid, with no holes in them.

 

I got lucky in a way, because if it wasn't for a coolant thru tools we use i wouldn't have cought it so early. There was some minimal coolant sipping into a spindle, just enough to alarm me, but not enough to do any damage...

 

[?Mark]

quote:

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You contact them yet ??

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We went thru our reseller.

Lyndex wanted to see them so we shipped them there.

After a couple of weeks we hear, "yeah, they're cracked allright, buy yourself a new ones..."

[David from FN MFG.]

we have had the same problem with our Mori's here in the past. Never have resolved the problem or pinpointed a cause. clamping pressure tests,tool change sequence test, ect. (i personally have not seen this happen to another machine tool as much as it has on Mori's but we have not been able to prove anything.) However we have changed suppliers for our pull studs and are keeping our fingers crossed.

[Guest CNC Apps Guy 1]

Any possibility they were over tightened? I know every shop has a magilla-gorilla that tightens the $#!+ out of everything.

 

Personally, when I tighten pull studs, I pull them snug and If I'm worried about them loosening up, I'll put some loc-tite on too. If you tighten them too much more they run the chance of expanding the taper at the back and you don;t get full taper contact in the spindle.

 

On a related matter, a company I was doing some contract work for uses a LOT of form tools. Anyway, we had one tool that had like .0045" runout. so we pulled the tool out and checked it - perfect (or as clost to it as we could measure). Too much force on the set screws pushed the tool out of round. So we tightened it snug + a little(the tool was not exposed to too much cutting pressure. Runout down to .0006.

 

Overtightening causes a crap load of issues and should be looked at when things go wrong.

 

JM2C

[?Mark]

quote:

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I know every shop has a magilla-gorilla

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LOL

I'm it I guess...

Snug + a little tap + medium loc-tite (for sealing reasons).

 

PositiveRake,

Yes, new moris (the last few years) have tool clamp power 1.5 times stronger that previous generation.

It's some 12,000 N now.

 

But I have a feeling there is more to Lyndex changing shoulder thickness of their pull studs then looks...

 

Love their tri-lock big plus holders, but they fu#ked up on this one IMHO

 

[Chris Rizzo]

You have a drawbar gauge? I wonder how much pull those machines have.

[Guest CNC Apps Guy 1]

To be fair, I've never been a real fan of the skinny pull studs (Mori, Haas, Cincinati, etc...). I like :gasp: the Fadal style pull studs or the Kitamura Sytle. I'd bet money the Fadal pull studs never failed the way the others have.

 

I have a small (6" I think) Crescent wrench. I use it for 40 Taper Pull Studs AND ER16 and smaller Holders. I've never had a tool pull out (that I tightened properly ) and I've NEVER had a pull stud come out or even loosen (knock on wood) doing it that way. There is just no need to tighten the $#!+ out of them, no need. Actually they would have to loosen beyond the stroke of the draw bar to have a real problem (unless you're doing so HEAVY roughing) because the drawebar is ALWAYS pulling on the stud so there is ALWAYS force being applied.

 

JM2C

[Bob_Looney]

So I really don't need that 16" Cresent and 2' piece of 2" black pipe?

 

thanks for the heads up, all 70 of my studs for my NV are the .250 type and look OK.

[Guest CNC Apps Guy 1]

[?Mark]

quote:

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You have a drawbar gauge?

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No, we don't, but 12,000 N is mori's number.

Newer mori's supposedly have a stronger collet allowing for 50% increase in pulling power.

 

Have no issues with command pull studs, and I've been installing them for 16 years here.

 

Those thin from lyndex looked wimpy to begin with

 

Anyhow, I'm glad I cought it before somebody got hurt or it ruined the spindle.