Advice needed: Material and weld process type for this assembly.

[Freedommachine]

I have to make 200 of these assemblies. The center piece will likely be made from low carbon steel, seamless hydraulic tubing.



The small plug on the right gets fixed flush into the end of the tube. I was thinking of brazing them. I have very little experience brazing - to my inexperienced mind this looks like a good application for it and a good opportunity to gain some experience. To clarify, I'm talking about a brazed solder joint, not tig brazing.

Based on the numbers from my AWS brazing handbook, I know the application will be well under the yield strength for this type of weld.

The piece on the left; I was planning to tig weld the end with ER70 in a joint prepared like this:



I cannot go into too much detail on the application of this assembly so my questions are more related to material weldablity and production efficiency. I have some technical knowledge but very little hands-on experience with production welding.

Is there a free machining steel similar to 12L14 but without lead that I could use in this application?

Is 12L14 as horrible to weld as the internet claims? I could use 1018 if necessary but I was hoping for something with a bit better machinability if possible.

Is my approach to welding these components reasonable from an efficiency standpoint?

Thanks.

 

[Kustomizer]

Stressproof welds and machines nice

 

[Mud]

Stressproof welds and machines nice

How do you weld it? TIG makes kind of a mess for me. It works, but it's not attractive, and undercuts a lot.

 

[Vancbiker]

You can get non- leaded steel 1215 that is pretty good machining.

I think tig would be faster than brazing.

 

[Herding Cats]

I was always under the assumption that all free machining steels were prone to cracking if welded.

Even if stressproof is "weldable" the carbon content is high enough to require post weld heat treat.

 

[Vancbiker]

I was always under the assumption that all free machining steels were prone to cracking if welded.

Even if stressproof is "weldable" the carbon content is high enough to require post weld heat treat.

Yep. Phosphorus is common in free machining steel and is a contributor to post weld cracking without pre and post heating.

 

[Freedommachine]

You can get non- leaded steel 1215 that is pretty good machining.

I think tig would be faster than brazing.

1215... ok, I'll get a quote for that thanks.

You're probably right about tig. If I had an induction heater, I bet I could beat the tig. I've been wanting one for a few years now but everytime I get $1500 I don't need, something more important comes up.

I'm really hoping I can find the tube. It exists in catalogs but no one seems to be able to get it; 9/16" x 0.035" wall.

I sent out an RFQ to a tube laser shop to see what they would charge to cut and send me finished tubes. Hopefully they have better luck. It will suck bad if I have to buy bigger stock and turn the o.d.

Thanks for the replies everyone, I'm still interested in whatever y'all have to offer on this!

 

[Kustomizer]

How do you weld it? TIG makes kind of a mess for me. It works, but it's not attractive, and undercuts a lot.

In talking to the customer, he MIG welds it, I have only seen pics of the assy

 

[Garwood]

What would be the struggle if milling that part from 1018? 1018 is not bad to mill at all. I hate turning it though.

 

[Barbter]

Tig would be less cleanup than braze (unless you vacuum braze).
But would there be any issues welding 35thou wall tube to the block - would you have to add a bit of preheat (torch) first to avoid any crack?

Plug on end - depending upon materials/load/application and tube bore tolerance....Loctite?

 

[Garwood]

Could you add cross holes to the blocky piece so you could plug weld the tube in with mig?

 

[MwTech Inc]

plug on the end, closed I assume?
if so, tig
the plug should have a flat face, truly flat face so the tube and plug face are perfect together.
If the tube is square and the plug has a round edge it will make it much slower and more difficult to weld.
Use a rotator,(if you want really pretty welds) weld plug in first. filler rod not required. Easy job.

the plug may try to "drop" in the tube due to expansion, a backup shaft inside the tube may be needed.
Repeat on other end, but you must tack both sides of the notch first, then go around
Op ..reread the post and i see you tig....anyway...... my 2 cents..lol

 

[MwTech Inc]

Could you add cross holes to the blocky piece so you could plug weld the tube in with mig?

He could but the hole would have to be fairly large and the heat most likely mess things up, picture shows quite a difference in thickness between block and tube.

Nice sharp tip on the tigger and you can just roll right around that little tube

 

[Barbter]

plug on the end, closed I assume?
if so, tig
the plug should have a flat face, truly flat face so the tube and plug face are perfect together.
If the tube is square and the plug has a round edge it will make it much slower and more difficult to weld.
Use a rotator,(if you want really pretty welds) weld plug in first. filler rod not required. Easy job.

the plug may try to "drop" in the tube due to expansion, a backup shaft inside the tube may be needed.
Repeat on other end, but you must tack both sides of the notch first, then go around

I saw it as open end - a bush....but if it is a closed plug then I'm with you 100% - square/sharp edge for plug and bore and Tig/fuse (no filler) on a turntable.
Possibly make plug tapered OD and tap (mallet) into bore flush to end which holds it into position for welding...

 

[MwTech Inc]

Barbter
yea picture show bushing, but we are talking plug??
Unless we are getting too old to see....lol

 

[Barbter]

Barbter
yea picture show bushing, but we are talking plug??
Unless we are getting too old to see....lol

Yes - zoomed in it's solid with a deburr/chamfer which fooled my 'ol eyes!

 

[MwTech Inc]

Well the chamfer got to go....lol

 

[MwTech Inc]

I assume op is making the plugs so a square end should be no problem.

 

[Freedommachine]

What would be the struggle if milling that part from 1018? 1018 is not bad to mill at all. I hate turning it though.

Surface finish is the main reason. The other being machinability itself. If I can get faster cycle times, longer tool life and a better surface finish from one material over another, I'll take it. Providing cost is about the same of course.

Could you add cross holes to the blocky piece so you could plug weld the tube in with mig?

I could, but idk how much it would help since the tube is so thin. My luck, I'd alternate between blowing thru and zero penetration just creating more work for myself.

plug on the end, closed I assume?
if so, tig
the plug should have a flat face, truly flat face so the tube and plug face are perfect together.
If the tube is square and the plug has a round edge it will make it much slower and more difficult to weld.
Use a rotator,(if you want really pretty welds) weld plug in first. filler rod not required. Easy job.

the plug may try to "drop" in the tube due to expansion, a backup shaft inside the tube may be needed.
Repeat on other end, but you must tack both sides of the notch first, then go around
Op ..reread the post and i see you tig....anyway...... my 2 cents..lol

It is a solid plug. Thank you for the tip about keeping the ends square. I woulda chamfered all of them and screwed myself. I added a 1/8" hole on the end so I can slip a pin thru and keep the plug from falling in while welding.

You think I can get away with no filler for both welds?

Tig would be less cleanup than braze (unless you vacuum braze).
But would there be any issues welding 35thou wall tube to the block - would you have to add a bit of preheat (torch) first to avoid any crack?

Idk. Should I be concerned about it cracking? I figured the slot in the tube would prevent it but I don't know for certain.

I'll have to look around for a rotary table type thing. It's been on my "nice to have" list for awhile. If anyone has a small one on the shelf collecting dust, maybe we could work something out

 

[Spruewell]

Brazing has its benefits too. Especially for larger quantities. Put a “j” root on the end of the plug and stick a ring of braze on it, press it into the tube. Then put a ring of braze on the joint between the block and the end of the tube. Stand them up and slip them into a kiln. Turns it into a batch process requiring minimal skill and produces very consistent results