Welding Tips and Tricks

G'day,
While I did a little gas and stick welding at school and I can still do very ugly welds in a pinch, what I need now is some advice of a machine welder.
Right now, I'm building a part that I could either contract out to a specialty shop, or invest in equipment and do it in-house.
For the part I need to weld a 1.5mm wire to a 5mm sphere (ball-bearing shape), such that the wire will protrude directly out of the ball, as if from the center. The closest thing I've seen that resembles what I'm needing is a piece of body-piercing jewelry called a dumb-bell, but in my case only one end has the ball.
I'm looking at thousands of individual welds, and I'll be using SS in one situation and a Ti alloy in another.
To ensure a strong and uniform connection the ball will be pre-drilled with a hole to accept about 2mm of the wire's end.
Ideally the weld would be 'inside' the ball - and not leave a bead/collar around the connection point, but this is not critical.
So... I really need a machine that I can set up with a jig, so the process is consistent and fast.
My questions are;
What is the best type of welding technique - TIG, fusion, or should I be looking at electron or laser welding?
Does what I'm calling the 'hidden weld' have a technical name?
Any recommendations or pointers that will send me in the right direction?
Cheers!

Hi there,

The thing that comes to mind when i read your discription is furnace brazing, Automatic machines that are used to join small complex parts.

http://www.furnacebrazing.info/

I have no idea how much these machines cost and if its even the right idea, but its a start.


This is a link to some machines. Theres some little ones about half way down the page. SMT Max is the manufacturer.

http://www.directindustry.com/industria ... 77210.html

I think for something so fine in such large numbers this is an option. Dont quote me though.

Mick

Thanks Mick. That might be an option, though the part has an awkward shape that could be a problem for volume, or might involve a large and more expensive machine, which is not where I want to go at this stage. Makes a lot of sense for large volumes when set up. Certainly worth investigating.
There are some dimensional differences with different versions of the part, and from the perspective of starting with smaller production runs I was thinking more along the lines of a simpler machine with an individual 'load and shoot' operation, and upgrading with more automation for larger runs.
Cheers!

I would consider 'Induction Brazing' for this task. Fast and efficient.

http://www.youtube.com/watch?v=MF-lXIkAaIY

http://www.youtube.com/watch?v=WHvXWTwZyDE

How 'bout a simple stud welder? It's resistance welding like a "spot welder", and works with small wire/rod sizes.

If you're looking for semi-automatic, as in load the part, pull the lever, press a button, I can see this as a viable option.

A number of suggestions come to mind, but some questions do as well. What rate of production do you require? Is this in a professional shop subject to job safety regulations, or in your garage? (Or something in-between?) How long is the protruding wire?

My first inclination is to adapt an auto-body stud-welder (1.5mm collet shouldn't be a problem) to an old drill-press frame, with a fixture for the sphere bolted to the table. Reliable repeatability on the cheap, with readily available equipment. A shallow (<1mm depth) bore in the sphere, with a dia. of, say, 1.75mm to allow some "squash" of the business end of the wire sounds like a starting point, but would require some fine-tuning.

Steve

Thanks again.
I don't think the stud welding will work as the wire part has an irregular shape, but it was a good idea.
The project might start out a little 'garage-ish' but before long I'd be needing higher output, and conditions to match.
The drill-press idea is interesting - maybe I can use that but lock the wire-piece onto the base and fit the press with the ball? I'll play around with that idea - so thanks.
I'll have to check into the induction brazing, but based on the videos, that looks like it will be too slow and labor intensive. The wire part is also an awkward shape which might give me problems with the coils. But thanks all the same.
Cheers!

Stud welding was the impetus for the idea. If the "adapted" stud gun won't work--

I think resistance welding is the only way you can do this rapidly AND accurately. The other methods suggested are not "welding", but brazing or soldering methods. If the customer wants "welded", these won't do, and I have a hard time thinking of another method that won't leave a "ridge" where the wire exits the sphere.

I suppose it could be done in a friction-stir process, but the equipment will cost more.

I work in the aircraft industry and this is how we attach a ball to a cable.
http://www.dmctools.com/Products/swaging_tools.html
You had better watch your fingers, because this pneumatic impact tool
does a really good job at putting a stainless steel ball on the end of a cable.

Otto Nobedder wrote:Stud welding was the impetus for the idea. If the "adapted" stud gun won't work--

I think resistance welding is the only way you can do this rapidly AND accurately. The other methods suggested are not "welding", but brazing or soldering methods. If the customer wants "welded", these won't do, and I have a hard time thinking of another method that won't leave a "ridge" where the wire exits the sphere.

Hi, if the ball is soft, it could be predrilled to depth, then the wire is rammed into the hole with a stud welding type weld .......there would be no fillet if the wire makes contact and welds when it reaches the bottom of the hole.....the weld cycle is initiated at the point when the wire reaches the bottom to prevent premature welding to the top of the hole.


Depending on the production rate per hour, day, or week etc, it might be better to buy in the balls CNC drilled to contract.....it's going to cost you time to drilll or spark erode them yourself anyway, but if you have the time, then it's your choice.

Bear in mind that a CNC lathe etc, will need to hold the balls firmly, and as they're soft that could lead to damage from the holding method.......probably soft jaws etc, whatever.

If the volume per order is low enough then a session drilling balls would probably be cost effective, but I would be looking at a years supply, probably in the thousands, CNC drilled outside.

Would the ball assembly be strong enough if the wire was pressed into the hole?

How much axial force would the balls be subjected to on the wire?

Could the hole be drilled right through the ball so that the wire could be lightly pressed in and Tig welded on the far side and then re-polished to clean up?

Could the wire end be tapered for 5mm and the hole taper drilled and the wire then pressed in and riveted on the far side, and rep-polished so no welding required?

Could the wire be inserted into an undesized hole by high frequency vibrational insertion force?
Ian.