Bore Problems

Hi everyone. I'm running some Licon 5 axis CNC machines (machining cast). I have a boring tool that roughs and finishes with the same tool (4 sided cutter). The issue I'm having is the size I set the tool to is way under than what it finishes as. I set the tool to 66.85mm and It comes out at 67.2mm. I've checked the HSK100 tool for burrs/damage, I've stoned the face of the spindle (it's being held solid by the collet), I've tried just about ever speed and feed but nothing seems to work. I even swapped the spindle assembly and motor. Any ideas suggestions would be much appreciated because I'm at a loss as to why I can't correct it. Oh yeah, we use a lubrix misting system with lubricut cutting oil (on max mist setting)

Cheers,

-Jeff

What's the diameter of the bar and length of the bar hanging out? It could be deflecting.

AARONT said:

What's the diameter of the bar and length of the bar hanging out? It could be deflecting.

Click to expand...

It's a straight tool about 360mm long and 63mm diameter on an HSK 100 mount (all 1 solid piece). It does not interpolation. Just straight in and straight out.

The whole bore from front to back (70mm total thickness) is out.

There are so many things that can go wrong with a rough finish combination tool it's hard to list them all. How much stock are you trying to remove? How much is left for the finisher? Is it a 3 flute rougher and single point finisher or is it two and two? What is the length and rigidity of tool, the fixture, and work piece? Is the roughing section clear of the bore before the finish section starts, or are they both engaged simultaneously? How much chip clearance do you have?

I think the most common problem is the rougher cutting the finished bore and then no adjustment with the finisher will make any difference.

gbent said:

There are so many things that can go wrong with a rough finish combination tool it's hard to list them all. How much stock are you trying to remove? How much is left for the finisher? Is it a 3 flute rougher and single point finisher or is it two and two? What is the length and rigidity of tool, the fixture, and work piece? Is the roughing section clear of the bore before the finish section starts, or are they both engaged simultaneously? How much chip clearance do you have?

I think the most common problem is the rougher cutting the finished bore and then no adjustment with the finisher will make any difference.

Click to expand...

The rough inserts are removing 2mm. The finish inserts are removing 0.5mm. The rough tool is clear of the part before the finishing inserts go in. 4 roughing inserts. 4 finishing inserts. The tool length is 360mm. It's solid in the collet. The part is hydraulically clamped and is very solid as well.

Four finish inserts? Personally, I would pull three of the finisher inserts and single point finish it. Depending on your results maybe introduce a second finish insert.

Is this a new tool that has not been used before, or is it a proven tool that is now misbehaving? have you pulled the tool after the roughing section and physically measure the actual rough bore diameter?

This does sound like a very expensive tool, and one would hope it does what it says it's going to do, but I say... why does it matter at all what it says on the dial of an adjustable boring device? The bore doesn't match the numbers on the dial? So what. Adjust it to get the finish diameter you want and forget about the dial numbers. Use the marks as reference, just like you'd do on a simpler adjustable boring head.

If there is no control over the finish diameter part of the boring tool then I take all this back. And if that is the case, maybe an incorrect insert with the wrong corner radius is being used.

Dave

.35mm / .014 is a mile for a job like that..

I would first consider the boring head set-up procedure. Could be the inscribed circle of the rougher blades are .007 off that of the finishers. Are you rotating the head and indicating as held off the shank as in the machine? Second, I would mount the cutter in the spindle and indicate it as it is held in the spindle.

Is the cutter head set-up to the center of the part.. is there a pre-hole that pulls the cutter head off location of the part.

The very best method would be to have a cutter head set at .005 / .010 over target size and circle grind a tickle land at the OD...cast favors a small land on the OD. Yes, a small OD grinder with a diamond wheel needed but would pay for itself in a very short time.

A 4 insert and 4 insert finishing head is like a reamer so one has to think like reaming not boring.

Does the boring head have a front and rear center? do you have an OD grinder,TC or surface grinder? surface grinder.

Is this a production run job?

Cast likes a negative top rake with a sharp edge. Or a positive rake with a negative top land perhaps .005 to .040 at the top of the cutting edge but still sharp. And a circle land on the following at the OD.
I used to be in charge of major manufacturing cast iron cutting tools. It is surprising how cast is so little understood. Cast is more like Ice. It likes to fracture ahead of cutting pressure not shave off as one would think aluminum, steel or plastic might. Often cratering behind the cutting edge is a majur wear factor alomng with nuch heat..

I have thought about a cutter head with a single insert to single point bore a lead hole in a part at slower but a short Feed to locate a bore to part holding center and the follow with a multi blades/inserts to make size and finish but have never made such a cutter and now that retired likely will not make one. Yes, the single point would have a different tool change number.

Qt:[(on max mist setting) It is not uncommon that flooding is better than mist.

Jefftiers said:

Hi everyone. I'm running some Licon 5 axis CNC machines (machining cast). I have a boring tool that roughs and finishes with the same tool (4 sided cutter). The issue I'm having is the size I set the tool to is way under than what it finishes as. I set the tool to 66.85mm and It comes out at 67.2mm. I've checked the HSK100 tool for burrs/damage, I've stoned the face of the spindle (it's being held solid by the collet), I've tried just about ever speed and feed but nothing seems to work. I even swapped the spindle assembly and motor. Any ideas suggestions would be much appreciated because I'm at a loss as to why I can't correct it. Oh yeah, we use a lubrix misting system with lubricut cutting oil (on max mist setting)

Cheers,

-Jeff

Click to expand...

From my vantage point, your tool is cutting oversize, not under.

gbent said:

Four finish inserts? Personally, I would pull three of the finisher inserts and single point finish it. Depending on your results maybe introduce a second finish insert.

Is this a new tool that has not been used before, or is it a proven tool that is now misbehaving? have you pulled the tool after the roughing section and physically measure the actual rough bore diameter?

Click to expand...

I'm with Bent.

Since we don't know how you are setting your 4 inserts, I'm wondering if you have 66.85 accrost each 2 inserts, yet they are not exactly on center?
(cutting OVERsize)

I have never used a tool like this, but always question the ability to get multiple inserts THAT close to perfect.

I would think that you would need a "presetter" that is made to revolve the toolholder, with an indicator on it that hits each insert as they come around. I am sure that you could doo the same in the machine spindle as well.



EDIT: I re-read it one more time, and I guess you weren't thinking that it was cutting under - like I originally thought at first (and second) time through.
However - I still say that at least one insert is hanging out.

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Think Snow Eh!
Ox

Were it me...I would remove the Finishing insert completely. I would want to see what the Tool was doing step by step. If that isn't possible, then I would get a pile of set-up material and start figuring out what's going on. Because the Feed must be the same for both Roughing and Finishing, it'll be hard to tell which insert is working.

That's where I would start. Also set it up in the Spindle and set up an Indicator, and start rotating the Tool around to figure some shit out.

R

Then how are you making parts?
Is the difference of .35mm from tool set to part bore…constant or varying?
If you measure over inserts and they are not true to cutter center line that measure is worthless, such a measure and set cutter will cut oversize..
A master diameter gauge to set your indicator... and then rotating the cutter under that indicator set as it sets in the machine might/should work. But if a rough bore location is pulling the tool off you are still in poor shape.
It seems you should run .002 or better. We had a set-blade reamer that would run to <.0002..but it was a headachs machine..huge waste of time and money..
At the big shop we called a multi insert or multi bit cutter a cat head. mostly they would cut a multi shape part or a number of steps, often to .001 or so..

Possible with an open tool positiom you could bevel the part bore, so it becomes properly centered before the boring head comes in..Yes If that is your problem..but likely it is just the cutter.

Cutter head somethung like this?
HSK100 tool cutter - Yahoo Image Search Results