What's new
What's new

How to Cut, Chamfer, and Clean OD of Tubing

Nerdlinger

Stainless
Joined
Aug 10, 2013
Location
Chicago, IL
We handle a range of tubes that need to be cut to length, chamfered (deburred) on both ends ID and OD, and clean up the outside (not to any specific dimension...just "clean". The smaller is probably 3/4" OD X 16 ga wall X 4" long and the largest is probably 1-1/4" OD X 3/16" wall X 24" long.

We currently 1) cut in automatic feed band saw 2) dump parts into baskets and put in degreases 3) put parts in a "tube facer" machine we made with two opposing drill heads where the part is clamped in a V-block then the drill heads approach both ends of the tubes with special cutters we made that hold carbide inserts that hit the outside edge, inside edge, and the end (so three edges are put on) in order to get the tube to the right length as well as chamfer the OD and ID 4) pass the tubes through a centerless grinder until the as supplied "scale" is removed so the part is clean and shiny and ready for plating.

This is a ton of "in the tub", "out of the tub", etc. handling. I could see putting the smaller tubes in a lathe to chamfer, turn, and cutoff but I can't do that on the 24" long tubes. Does anyone have any idea how tubes are cut to length, chamfered on both ends, and cleaned up on the OD??????? Thanks!
 
What tolerance range are you looking for? Equally with regard to the plating, is it decorative or functional? Assuming were talking steel tube here?

Can you maybe set things up as a cell like arrangement, saw drops in basket - still-age, gets picked up from there, de-greased, faced and dropped into grinder with out being re-stacked? If your plating in house can the grinder unload then get loaded straight onto plating racks?

Switching to a cold saw would get you square true nice ends, that a common of the shelf tube de-burr machine would just need each end jabbed into it to do its thing, thats the point i would then degrease - clean at, then grind.
 
Could you grind the OD before cutting to length, I mean when the tube is 20 feet long

I don't think we would have the room to feed an entire bar safely through the center less before...and then they'd probably get all scraped up during the successive ops...
 
What tolerance range are you looking for? Equally with regard to the plating, is it decorative or functional? Assuming were talking steel tube here?

Can you maybe set things up as a cell like arrangement, saw drops in basket - still-age, gets picked up from there, de-greased, faced and dropped into grinder with out being re-stacked? If your plating in house can the grinder unload then get loaded straight onto plating racks?

Switching to a cold saw would get you square true nice ends, that a common of the shelf tube de-burr machine would just need each end jabbed into it to do its thing, thats the point i would then degrease - clean at, then grind.

The diameter tolerance is purely aesthetic, so we're usually taking off .005" max just to shine it up.

Plating is decorative nickel chrome.

Everything is steel.

That's about what we do, regarding the "cellular" layout...the end of the saw, degreaser, and "tube facer" machine are all a couple steps away from each other, but the saw gets ahead of the other ops. The grinder is farther away and "should" be closer but most part require more than one pass in the centerless to fully clean them up and the longer bars need two people - one to feed into and one to catch from the centerless.

The plating is in a separate building so that sucks.

You're right - a cold saw should minimize the burr and make the sharp edge easier to roll over but we need the look of a "generated" chamfer/radius because these are for hand tools so that just looks and feels better.

It's just a lot of handling and difficult to really get all the various ops timed out right so that it's in a good rhythm. It sounds like we might be doing about the best we can...
 
In feed and out feed guides on grinder should be the first thing you do. It's easy and 2 people on a grinder is a huge waste of labor. Then work on not damaging the ground finish in the other operations after you grind the tube.
 
For your short ones up I would look at an old single spindle Traub A42 or equivalent. Add a rotary saw cut off for cleaner cuts, possibly use an internal relieving tool for the ID chamfer on the cut off side or just debur the inside ID by hand. Low budget automation.
On the long one other than a cold saw for cutoff you will be the expert when after a few years.
 
I don't think we would have the room to feed an entire bar safely through the center less before...and then they'd probably get all scraped up during the successive ops...

Cut the bars in half?
And as far as scrapes go, just need more care in handling.
The time and money saved in centerless grinding will make up for the time spent in care for handling IMO.

Or hire a kid at minimum wage to put the bars in an engine lathe with a tailstock and sand the o.d. with some emery cloth to clean up.
 
You can do what FredC suggests but I can't imagine the internal back recess working. Other than that then anything is possible.
My sequence would be,
1/ feed very short
2/ chamfer o/d both sides of part off
3/ part off
4/ chamfer I/d
5/ feed to stop.
Start again at 2/.
This method will allow for all lengths by feeding to a stop in the turret for shorter versions or feeding to a stop through the turret fixed to the casting of the turret.
You would not be the first person to do this.
You are probably right on the ID chamfer. We did use the longitudinal attachment on the front cross slide to do an ID chamfer on a very short part. 4 inch long part would be more difficult.

The idea of using a Traub is there would be no turret to complicate things. Put a chamfer tool in the drill slide and done. Simple machine with a few cams and you are in business. The rotary cut off would save stock and give a better finish, might save that option till after all the bugs are out of the system.
Also with a Traub it would be easy to modify the 12 foot bar feed to 20 feet, lengthen the guide bars and get a couple extra stabilizers.

Agree 100% on the sequence.
 
I may be wrong, but ..

Suggest:
Make a fixture/tool to power sand the outer D as a first op on longer lengths.
Half-tube, 3 m, or 2 m, maybe.

Using long/wide belts, and two separate opposed belts driven by 3-phase motors and vfds, belts slightly diagonal not at 90 degrees, the belts should drive the tube both around and forward in a controlled manner.
This should be extremely fast and efficient and leave a semi-ground finish.

Look at knifemakers belt grinders for inspiration, maybe.
I would expect maybe 1-2-3 minutes per metre length, perhaps less if you have power enough.

If dirt and millscale degrade/clog belts fast, a triple wire wheel before first belt might take off the crap, and last.
(Sandblasting with shroud ?, rotating media).

2:
Make a double cold saw tool to chop of parts, in v blocks, after the sanding op.
You should get 2 parts/cut, after the first end has been cleaned up in each tube length.
A cut might take 1 min cycle time (40 secs in cut maybe).

Have the 2 saws mounted on linear guides, so you can quickly and easily adjust lengths, and use tapered pins to lock them in place, precisely ?

Endless ways to make it more advanced and fancy, and fast, if needed.
You could scale/sand most of the OD while doing the ends.

Just run the ends only, say 10 cm, of the OD on the first sanding op, 60 secs, swap to next station, then grab and power-rotate the tube sanding OD while doing both ends simultaneously.
A few 400W Ac servos would swap tube positions in the line in a few secs.

I would expect the line needs no manual work at all.

The automation parts are cheap, and should cost less than 10k€.
 
If you have the cash to spend nothing will beat a proper tube cutoff lathe.

Rotating Head Cut-Off

At your volume I would just buy pre-cut tubes from a service center that has one.

I actually called Hautau like 3 months ago and the machine I would need was like $250k and it didn't chamfer or something...I just remember being able to buy a more-capable twin-spindle, Y-axis CNC lathe with magazine barfeed for the same money that would be able to chamfer (and skim cut the OD??). :confused:
 
In feed and out feed guides on grinder should be the first thing you do. It's easy and 2 people on a grinder is a huge waste of labor. Then work on not damaging the ground finish in the other operations after you grind the tube.


We do have guides that support the shorter parts on the way out but the 24" long part chatters at the last inch or so (when 23" inches are already "out") so the "catcher" has to squeeze the spring-loaded guides just enough to keep the part from chattering but not too much to resist the force of the regulating wheel on the grinder. Maybe we need to review those guides, despite it being, "...the way we've always done it!" :skep:
 
You can do what FredC suggests but I can't imagine the internal back recess working. Other than that then anything is possible.
My sequence would be,
1/ feed very short
2/ chamfer o/d both sides of part off
3/ part off
4/ chamfer I/d
5/ feed to stop.
Start again at 2/.
This method will allow for all lengths by feeding to a stop in the turret for shorter versions or feeding to a stop through the turret fixed to the casting of the turret.
You would not be the first person to do this.


Still chamfer the ID of the back side via secondary op, right?
 


I can't figure out those "cut off machines!" Do they just feed material some distance and cut off with a carbide cutoff tool like in a lathe, abrasive cutoff wheel thingy, etc? I can't tell if any of them chamfer ID/OD on both sides...do you know if they do that??
 
I may be wrong, but ..

Suggest:
Make a fixture/tool to power sand the outer D as a first op on longer lengths.
Half-tube, 3 m, or 2 m, maybe.

Using long/wide belts, and two separate opposed belts driven by 3-phase motors and vfds, belts slightly diagonal not at 90 degrees, the belts should drive the tube both around and forward in a controlled manner.
This should be extremely fast and efficient and leave a semi-ground finish.

Look at knifemakers belt grinders for inspiration, maybe.
I would expect maybe 1-2-3 minutes per metre length, perhaps less if you have power enough.

If dirt and millscale degrade/clog belts fast, a triple wire wheel before first belt might take off the crap, and last.
(Sandblasting with shroud ?, rotating media).

2:
Make a double cold saw tool to chop of parts, in v blocks, after the sanding op.
You should get 2 parts/cut, after the first end has been cleaned up in each tube length.
A cut might take 1 min cycle time (40 secs in cut maybe).

Have the 2 saws mounted on linear guides, so you can quickly and easily adjust lengths, and use tapered pins to lock them in place, precisely ?

Endless ways to make it more advanced and fancy, and fast, if needed.
You could scale/sand most of the OD while doing the ends.

Just run the ends only, say 10 cm, of the OD on the first sanding op, 60 secs, swap to next station, then grab and power-rotate the tube sanding OD while doing both ends simultaneously.
A few 400W Ac servos would swap tube positions in the line in a few secs.

I would expect the line needs no manual work at all.

The automation parts are cheap, and should cost less than 10k€.

Thanks! I like the idea of putting the belts at a slight angle to drive the material...I imagine you could even make that angle adjustable to change the rate at which the material is pushed forward? We can do something like this if it comes down to it but I didn't know if there was a more-or-less "standard" solution. It doesn't look like it....even the "tube cutoff machines" rarely chamfer the ends. Maybe we can get away from needing a "chamfered" end as long as the "burless" but isn't too sharp...
 








 
Back
Top