We've got this beast where I work. The max discharge is 2500 amp. It's rated to do 8, 1" diameter studs /minute.

 

We've got this beast where I work. The max discharge is 2500 amp. It's rated to do 8, 1" diameter studs /minute.

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Any idea what the input amperage/voltage is on that?

 

I've used CD welders for welding battery tabs when I worked for a consumer battery company. If I remember correctly, the maximum capacity for those machines was about 300 watt-seconds. I haven't seen a CD one for studs, but it must be pretty big.

 

Part of the job I had at one plant was repairing stud welders.
Studs were much smaller than shown in HT-2's pic. 10-32
or 10-24 (IIRC)welded onto sheet metal disc.One machine was
automated with studs fed automatically
from vibratory feed bowl. Machine (KSM) made about 30 parts/min.
I believe it ran on 230v 1ph and didnt draw a whole lot.
Hearing protection required,made a pretty good "Pop".

 

Im thinking that's a dual op stud gun setup, but done with the drawn arc technique, rather than cap discharge

 

Fred,

I believe you're right about that being "drawn arc" rather than "cap discharge". Been trying to find the operation and maintenance manual for it on line but no luck with that as yet. Did find this which gives some more info about it and will shed light on the amp / voltage input question.

http://www.nelsonstud.co.nz/documents/nelsonnelweld.pdf

I've yet to actually use it myself. Mostly the fitters put the studs on. One night this past week some one on night shift who obviously wasn't trained in its use used it to put on around 30 studs. Made a horrible mess of it and one of my fellow welders on day shift had to go around each one with metal core wire to fix them and make sure they stayed on. To start with it looked like he must have had the machine set way to hot for the size studs he was trying to put on because each one had a serious undercut / underfilled crater around it's base. That and they were all breaking back off with just a light tap from a hammer.

The stud welding I've been involved with in the past has almost always included the procedure of shooting a test stud to a piece of scrap and then taking a hammer to it as a way to confirm that you've got things set right and the stud will actually be welded on like it should be. If done right with the proper settings the stud will bend over 90 degrees and touch the base metal with out any indication of it wanting to tear loose. I've also read where on more critical applications the QC involves pulling a test stud with hydraulic force and recording the exact amount of force it takes to cause failure.

 

I've specified them in the past to attach ladders and insulation to pressure vessels. Nelson makes a wide range of pins and studs. http://www.nelsonstud.com/Portal/Products/Fasteners/Catalog/tabid/58/Default.aspx