[nelson]

Hey people!

I'm making a new injection mold to reduce waste, landfill trips, etc.

I'm doing the hard part last...as usual. It's a hot runner mold and the manifold is copper. I want good heat conduction to the copper channel from the manifold back to the sprue bushing and nozzle. Therefore I want to weld it.

My questions...how hard is it?
I have an Everlasting 164si. Argon. I have Si bronze filler I think. I could scratch up some copper filler ......or 12 gauge solid wire?....??

Thanks in advance for your attention girls and guys.

[Poland308]

SiliconBronze would be brazeing. If you want to weld it you will need copper for a copper to copper weld.

[Welder chimp]

Ok, I have no clue what most of that meant, but here’s how we weld copper in my shop. Tig DCEN 1/8 thoriated tungsten, helium shielding gas, deoxidized copper filler rod. Copper is such a good conductor so it takes a lot of heat to weld it. I’ve burned up a few torches doing this. Keep in mind what I’m describing is on 3/4” solid copper. I hope I got that right it’s been about 6 months since I’ve done this. It’s not too difficult to weld, helium was the key for us. Good luck

[Franz©]

Copper is a PURE BEACH.
I doubt you'll get sufficient thermal conductivity gain by welding as opposed to brazing to justify welding. Brazing may actually give you more thermal conduction if brass can cover more area of the weldup.

[nelson]

Thanks for the suggs.
Yeah, the manifold is 1 inch square, 5 inch long. I want this welded to a 1 x 1 x 1 extension to the sprue bushing...nozzle. Welded to enhance heat flow as much as stiffness so the manifold doesn't get...bent... from the pressure the molding machine nozzle pressing on this whole assembly.

I think it will work, Leaking is the big bit of the day. Any molder with hot bushing or hot runner experience knows the pain in the ass of a leak.
You have to go get the heat gun, thick gloves, and every EVERY shift, spend 30 minutes farting with an engineering shortfall melting and digging the plastic off the innards of a molding machine.. insert f word here.

Thanks guys.
I'm not going to get helium but will do the best I can.

[77cruiser]

Little bit I've done was easy.

[Coldman]

I suspect your 165 power source won’t have enough grunt for thick copper. You may have to consider helium if you don’t have a bigger green box.


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[nelson]

OK.
Silver solder. I'll join them with 1200 degree paste I happen to have access to. Functionally the part will never go above 600F so it should work.
I'll get the rosebud nozzle out and set about doing it.

[Franz©]

OK.
Silver solder. I'll join them with 1200 degree paste I happen to have access to. Functionally the part will never go above 600F so it should work.
I'll get the rosebud nozzle out and set about doing it.

Prepare your pieces with ultimate attention to cleaning and fluxing and heat gently. With silver bearing filler you get one chance. Remelt if you have to make a repair will be considerably hotter than melt on silver.

[nelson]

Thanks Franz.

I think that happened before but I didn't raise it...the first ti,e thing you mention...

[Poland308]

Need of flux depends on the rod. 5% and 15% don’t require flux they just need to be clean. But 45% or higher will need flux. If you get a rod that requires flux make sure it’s the right one. There not all the same.

[nelson]

I brazed it.I'm chicken shit. I'll try my deox copper filler rod on something less critical.
Stay tuned up.
NelZ

[Franz©]

I brazed it.I'm chicken shit. I'll try my deox copper filler rod on something less critical.
Stay tuned up.
NelZ

Lot to be siad for chickenshit. 60 years ago we heated castings for a few hours after chipping away at the weld area in wood fires, pulled them far enough out to work on them, and used war surplus piston rings for filler with an O/A torch. Then we put it back in the fire and covered it up to cool for a day or more.

10 years later we made equally good repairs with Everdure and a carbon rod in the stinger. Sometimes we used brass with an O/A torch.

In the 80s we put a lot of repair sleeves in the bores of fans, pulleys and blowers with brass. Also still did a lot of impeller blade buildups with brass so a machinist could whittle it back to size in a lathe that had been doing the job since the shop ran from a water wheel in the millrace behind the building.. Haven't done one of those since the 90s. Some genius decided the impeller could be replaced cheaper, and another genius scrapped the antique machine shop. Price of replacement impellers went way up not long after.

By turn of the Century lot of jobs the customer got 2 quotes, 1 for brass and one for epoxy. Most elected to try epoxxy when they heard the price difference. Pretty much every one of those jobs lasted longer than brass would have too. Last 10 years we've had glue for copper and brass to replace solder, silver solder and brass. The glue is equally strong and better than solder since we been blessed with lead free crap. 1 man can glue up more copper fittings in an hour than 2 men could solder, and there's no need for a FIRE watch for 3 hours after. Customer today rarely knows what's available, so they're real happy to hear we can do it for less than they anticipated and faster.

Best part is customers want to bring in the outside contractor rather than use their in house labor because contractors have more ways to do the job and no training costs are theirs to cover.

I walked in a shop Thursday looking for something I thought he might have or know who in town did have. Spent an hour with the owner learning a couple new processes I'd never heard of and seeing machines I'd only read about along with what I went there to look for. Need to go back next week to drop off a repair to him. I wound up with a whole new encyclopedia and a new buddy.

As you age you get smart enough to think of other ways to do the job before you jump into doing the job.