Jump to content

Welcome to eMastercam

Register now to participate in the forums, access the download area, buy Mastercam training materials, post processors and more. This message will be removed once you have signed in.

Use your display name or email address to sign in:

Fighting floor finish problems in Aluminum


Recommended Posts

I know my issues are machine specific and this may not be the best place to discuss but I am fighting swirls you can hang your fingernail on the floor finish of 6061.  No amount of feed/speed, tool path, etc will change that.  I have reviewed several parts from this machine and it just plain sucks and caused excessive debur times. 

 

I know we have some runout in the spindle due to the taper having a low spot so we test every single tool and make adjustments.  The tool we are using now is a 3/8" square end with .0008" runout. 

 

I have read that the head tram may be causing this and one that I sort of forgot about.  I also was thinking about spindle bearings but this spindle sounds just like new, no heat, no finish issue on the walls, and no dimensional issues that would point me to bearings.  That is an expensive "guess". 

 

For my tested floor finish, I am running a finish pass of .010" and another at .005".  There is no difference at all.  Really no difference between the rough and finish passes either. 

 

 

 

Any thoughts on the runout being the cause or tram?

post-22113-0-68953600-1464313398_thumb.jpg

Link to comment
Share on other sites

What rpm and what feedrate are you running at?

How many flutes is the 3/8" endmill?

A small corner radius on the endmill can't hurt, and it looks like you're feeding too fast for whatever rpm you're going.

Try feeding .003 i.p.t. or somewhere near that and see how the finish comes out.

Link to comment
Share on other sites

looks like a feed rate problem to me.

looks like about a .012" chip load.

 

if that is happening at a .003-.005" load, you have a bad cutter or excessive spindle end play.

  End play could be drawbar or bearing related. One workaround is leaving more material for finish, as it will push the spindle up and hold it there. I recently got an 11rms finish doing it this way on a 14 year old spindle.

HTH

Link to comment
Share on other sites

This finish is a .010 axial DOC, 60% step over, 7500rpm, 60ipm, 3fl cutter no radius.  I already plan to throw a radius cutter in but I also know it won't totally fix the issue.  There is something more going on.  We had an old CNC knee mill that would do a better finish than this! 

 

That other outer band to can barely see that is higher was the same but .005" DOC and 80ipm.  Pretty much no difference. 

Link to comment
Share on other sites

This finish is a .010 axial DOC, 60% step over, 7500rpm, 60ipm, 3fl cutter no radius.  I already plan to throw a radius cutter in but I also know it won't totally fix the issue.  There is something more going on.  We had an old CNC knee mill that would do a better finish than this! 

 

That other outer band to can barely see that is higher was the same but .005" DOC and 80ipm.  Pretty much no difference. 

Hmm, the speeds and feeds look fine to me.

Is the part being held stable to the table or fixture?

Are you SURE it's 6061-T6 and not one of the gummy crappy aluminums out there like a 0 temper?

Link to comment
Share on other sites

What does the "more material" part do?  Is there indication of what would be worn that causes this?  I am doing some machine testing now and it sure looks like the spindle taper may be the issue as there is a low spot and that is consistent with the runout at the tool.  We marked with a sharpie and then ran the tool. 

Link to comment
Share on other sites

If you have ever seen a single tool fly cutting operation finish, that is pretty indicative.

 

When flycutting all of the chip comes off on the lead of the path, as the tool is in the rear it's almost a sweeper action, no material, little tool pressure

 

The runout in your spindle is causing a very similar effect.

Link to comment
Share on other sites

I appreciate the responses.  We know we have runout that exceeds what is normal so I think getting that fixed would be best before we start trying to grind tools to fix it.  I know on other machined, we get the typical swirls but nothing you could hang a nail on. 

 

What we are trying to determine now is the taper or maybe even an odd drawbar pulling issue because the holder is getting very good contact and pros indicate if there is a small low, the rest of the taper should be correcting that and running the tool true.  Indication is bell mouth usually starts showing up and cause for grinding but we actually get good contact at the bottom. 

 

I am puzzled at the moment and hoping we have something like draw bar fingers causing this. 

Link to comment
Share on other sites

What does the "more material" part do?  Is there indication of what would be worn that causes this? 

first question: refer to post #8

second question: crappy finish would indicate it, in absence of anything else more obvious. misread the question, sorry. Common cause of endplay are worn bellville springs on drawbar retention springs. Also because the ejection force on Haas' get transmitted through the bearings it causes premature endplay.

Edited by mkd
Link to comment
Share on other sites

first question: refer to post #8

second question: crappy finish would indicate it, in absence of anything else more obvious.

Not interested in arguing but I think what you mean is "pull the spindle down" as the helix of the cutter would pull the cutter into the material.  This would be evidenced by pulling parts out of a vise.  I have never heard of them being pushed into the vise. 

 

I agree with what you are saying though.  However, I think we have pretty much confirmed we don't have a bearing issue.  Talked to 3 pros now and with good noises, no heat, no odd runout that is not consistent, no axial o radial play, we are chasing runout. 

 

I am testing now but strongly believing this is being caused by the drawbar.  I think the balls or the collet nose has an issue. 

Link to comment
Share on other sites

Not interested in arguing but I think what you mean is "pull the spindle down" as the helix of the cutter would pull the cutter into the material.  This would be evidenced by pulling parts out of a vise.  I have never heard of them being pushed into the vise. 

 

I agree with what you are saying though.  ...

no argument, just understanding; there is a possible quick fix for you, from other people's success and experience. :cheers:

 With proper cutter corner radius and depth of cut, i would hazard a guess the cutter is actually be pushing up. For example, .08 z depth with .125 radius.

Link to comment
Share on other sites

A few more cents...

 

There are some end-mills that have some sort of 'Wiper' geometry that can help with that. But they may cause the need of another flat end-mill or bull-nose to make the edges between the floor and the walls perpendicular again.

 

The other thing: Has the machine suffered any collision?

 

A misalignment between the spindle rotational axis and the table surface may cause this as well, and run out may not necessarily co-exist.

  • Like 2
Link to comment
Share on other sites

You should really consider a ball bar test for the machine. I've seen strange things before, like a "jog" in the ways of the Z Axis. So in most of the travel range, the axis was straight, but in a particular 2 inch section, the spindle axis would "shift" to one side, by up to .012 inches. It was basically impossible to "see" through manual gauging methods, but the ball bar test showed it right away. I think Daniel is spot on, that you may have a spindle axis that is not perfectly perpinduclar to the machine table.

  • Like 1
Link to comment
Share on other sites

Cutter geometry. You need an endmill that is still cutting towards the center of the tool, which creates a "wiper". You are currently using a tool with relief on the axial edges, which is great is you need to ramp into a piece of material, but lousy if you want a fine floor finish.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

  • Recently Browsing   0 members

    • No registered users viewing this page.

Join us!

eMastercam - your online source for all things Mastercam.

Together, we are the strongest Mastercam community on the web with over 56,000 members, and our online store offers a wide selection of training materials for all applications and skill levels.

Follow us

×
×
  • Create New...