Thread finish quality is poor

[DLo]

Changed from Synergy 735 to Castrol Syntillo 9918.

first problem is from changing from the best coolant in the world to the worst coolant in the world. - according to my boy Titans of CNC

 

[kevin66]

That's good info to have. Thanks for the feedback. At he risk of sounding like I don't know what I'm doing, how would A9 or other tapping fluid be used in an "enclosed" type machining center? Or are we talking about making it a separate step?

On the machines with that use 9918 its an M0, blow coolant from hole and use tapping fluid. On our Nakamura WT and MX520 we just use a coolant with better lubricity as stopping to add taping fluid greatly increases cycle time.

 

[Ox]

The part diameter is .95 in. I think the 1.16 is probably where it rapids to.

I'm a little confused, how can you speed up the spindle speed and slow the feed while tapping? Wont this just strip out the threads?

The threads are only 4-40, what ccmt inserts would apply to this?

It's OK, none of the rest of us have any clue either.


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I am Ox and I approve this here post!

 

[Houdini]

It mentions "mineral oil" a cpl times, but also says "synthetic", so not sure which it is?

But the cheat sheet does confirm that tapping is not one of it's key apps.

https://msdspds.castrol.com/bpglis/FusionPDS.nsf/Files/B8D42ECF5700FFE480257FC4002D9E0F/$File/459389_XI_en.pdf

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I am Ox and I approve this here post!

yeah what a bunch of idiots, Synthetic (but has mineral oil) genius.
makes me wonder percentage, some are mostly mineral or mostly ester, but more expensive are less mineral or ester and more Lego's.
the less mineral the poopier it will be like a full-synth.

 

[Houdini]

It seems to me that the piece D is either 1.16 in (inches, yes ??) radius or in diameter, don´t know the codes well enough to immediately identify.
And it seems You are starting with S500, spindle rpm of 500.

Suggest:
Start with spindle rpm of 3000.
(for 2" D workpiece 3000 rpm should be fine, and most/all chucks and collets are safe at this rate).
Your problem will probably go away.

Perhaps reduce feed/turn by 50% if needed.

Use ccmt inserts if needed, they will not tear the material, within reasonable conditions.

I think you need to put the bong down bro,
re-read his post

Its a 4-40 tap on a radial live tool.

 

[LockTech]

first problem is from changing from the best coolant in the world to the worst coolant in the world. - according to my boy Titans of CNC

lol, I agree. However we cut a lot of brass and the 735 was well not great at keeping things from getting gummy.

 

[Houdini]

I am sorry, but stating that a full synthetic coolant, regardless of mfg. as the best coolant is laughable

 

[ToolmakerTH]

Another possible reason beside coolant change and material change since the last batch you ran these parts is the tap. Has this tap you are using been used on another material type since it was used last time on this job? If it was used in steel or something harder than aluminum, the forming edges on the tap could change and it won't "cut" the same.

 

[AARONT]

As mentioned, that looks like a coolant problem. Have you validated the coolant concentration in the machine? If that's good, toss an M00 in there, turn the coolant off and lube the hole up with some tap magic, anchor lube, or whatever else you have. I would also ditch the TiN coating on the tap and go uncoated.

 

[LockTech]

Another possible reason beside coolant change and material change since the last batch you ran these parts is the tap. Has this tap you are using been used on another material type since it was used last time on this job? If it was used in steel or something harder than aluminum, the forming edges on the tap could change and it won't "cut" the same.

I plan to examine the tap well today and even swap it out to eliminate that possibility.

 

[LockTech]

As mentioned, that looks like a coolant problem. Have you validated the coolant concentration in the machine? If that's good, toss an M00 in there, turn the coolant off and lube the hole up with some tap magic, anchor lube, or whatever else you have. I would also ditch the TiN coating on the tap and go uncoated.

Good info, I do know the coolant concentration is correct. I have to figure out what command will let me pause the program prior to the tap cycle and allow me to open the door a manually lube the tap hole.

 

[Ox]

M0

Or M1 with the Optional Stop button lit on the HMI


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I am Ox and I approve this here post!

 

[LockTech]

UPDATE:

First I found some old stock to try. This yielded the same results.

Second, I manually lubricated the tap cycle. This definitely helped, so I do believe the coolant is partially, probably mostly to blame.

Third, I examined the form tap. The tap itself looked very good, however it does have some gummy aluminum buildup on it that I'm sure is affecting the thread finish as well. I'll try ordering and using a non coated tap to see if this helps.

QUESTION:

If I were to change coolants again, what suggestions do you have? Keep in mind this machine cuts aluminum and brass mostly. Brass being the issue with using most coolants as it reacts easily.

 

[Houdini]

semi-synthetic mineral base.

Just as reference I use Oemeta Novamet 910 specific for Aluminum and Yellow metals.
I changed to this due to a lot of 7075 injection molds back in the day.

And actually that gummy build up you mention gets diluted with this coolant, it actually allowed me to use tiny reamers in thick mold plates due to the wash out properties,
the Hangsterfers, and Qualchem didnt.

Due to this wash out, my machines are super clean, and that Aluminum gummy black shit floats in the coolant tank to be removed later.

2 cents

 

[EmGo]

Third, I examined the form tap. The tap itself looked very good, however it does have some gummy aluminum buildup on it that I'm sure is affecting the thread finish as well. I'll try ordering and using a non coated tap to see if this helps.

If you are willing to play with taps, you could try a cutting tap instead of a forming one. 6061 is such gooey awful stuff that it might work better.

(I am not a huge fan of form taps, altho some people love them)

 

[Wsurfer]

FWIW,
I use Trim 685 at 7% form tapping (flood coolant on a Brother) @6000 rpm 0-80 threads, come out beautiful.

 

[Ox]

If you are willing to play with taps, you could try a cutting tap instead of a forming one. 6061 is such gooey awful stuff that it might work better.

(I am not a huge fan of form taps, altho some people love them)

Yeah, if lubricity with your current coolant is lacking, the quickest/easiest fix here would be to go to a cut tap.


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I am Ox and I approve this here post!

 

[LockTech]

If you are willing to play with taps, you could try a cutting tap instead of a forming one. 6061 is such gooey awful stuff that it might work better.

(I am not a huge fan of form taps, altho some people love them)

We actually started with cutting taps on this and found that form was working out much better with such small taps due to less breakage. However I would imagine cutting threads would leave much nicer surface finishes

 

[Houdini]

We actually started with cutting taps on this and found that form was working out much better with such small taps due to less breakage. However I would imagine cutting threads would leave much nicer surface finishes

I do the same, in Aluminium if I have small taps that keep breaking, fuq it, I roll with a form tap.
especially if its small and bottoming, damn engineer!

I have had customers actually demand the roll tap for the added strength of the work hardened thread.

 

[ToolmakerTH]

UPDATE:

First I found some old stock to try. This yielded the same results.

Second, I manually lubricated the tap cycle. This definitely helped, so I do believe the coolant is partially, probably mostly to blame.

Third, I examined the form tap. The tap itself looked very good, however it does have some gummy aluminum buildup on it that I'm sure is affecting the thread finish as well. I'll try ordering and using a non coated tap to see if this helps.

QUESTION:

If I were to change coolants again, what suggestions do you have? Keep in mind this machine cuts aluminum and brass mostly. Brass being the issue with using most coolants as it reacts easily.

If your tap has build-up of aluminum like in the picture, that is what causes the bad threads. The first hole might be fine but after just a tiny bit of build-up, you won't get good threads anymore. You either have to change to a new tap after that or you can try picking out the gummed up material on the tap. Lubrication is what most likely the cause of the gummy build up in the first place, just like others have mentioned. So, switching coolant will help. If you can't switch coolant for some reasons, changing to another tap model might help. I have found that some form taps do not work well on certain type of aluminums. I have parts on swiss lathes which are 3000 grade AL (very gummy and soft), universal grade form taps (I used OSG S-XPF taps) don't work well, even with the oil based coolant; the threads would come out like yours. So, I switched to specific aluminum form tap (also from OSG), and the threads are pristine. Due to limited sizes of the aluminum specific taps, sometimes I have to use the universal grade form taps on aluminum. The ones I have found to work wonderfully on aluminum are form taps from Seco; they even work well with water based coolant. I have tried universal grade form taps from Guhring (like yours), OSG, Yamawa, Emuge; none of them have worked as well as Seco on aluminum (3000 / 6000 / 7000 series).