Author Topic: Interesting  (Read 2914 times)

Billy

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Interesting
« on: August 20, 2006, 05:24:46 PM »
Anyone ever heard of "Powder Welding"? This uses a nickel powder, and a special oxy-acetlylene torch, and seems ideal for effecting low temperature repairs on cast iron. Heard of the process from a friend of mine who worked for many years in a railway engeering workshop, where they used the process for rebuilding worn train wheels.

Bill

rcavictim

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Re: Interesting
« Reply #1 on: August 20, 2006, 05:54:05 PM »
The modern large commercial wind turbines that have towers made from thick rolled steel sheets are powder welded.
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dkwflight

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Re: Interesting
« Reply #2 on: August 20, 2006, 06:25:49 PM »
Hi You guys are talking about different things. The oxy torch powder is in short a special torch that moves the buildup powder through the torch flame which is used to keep a melt puddle going on the surface that needs build up or a hard surface.
There is a version thauses a plasma torch to generate the heat. This is a better method for applying materials to a surface because a greater heat is used resulting in better fusion of the applied metal to the surface.
The welding method used on large assemblys is a wire welder moved by a trolly at a uniform speed to get uniform results. The flux is applied by a funnel to keep a pile around the weld puddle. one of the advantages is the flash is hidden in the pile of flux.
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rcavictim

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Re: Interesting
« Reply #3 on: August 21, 2006, 01:58:15 AM »

The welding method used on large assemblys is a wire welder moved by a trolly at a uniform speed to get uniform results. The flux is applied by a funnel to keep a pile around the weld puddle. one of the advantages is the flash is hidden in the pile of flux.
Dennis

A company with access to some serious coin put up forty five, 1.5 MW wind turbines close to me last summer and I inspected one of them close up in person while it was still laying on the ground.  I was guessing the wall thickness was maybe 1-1/4 to 1-1/2 inches thick steel plate rolled in a tapering cylinder and the joint welds were absolutely perfect seams maybe 7/8 inch wide and slightly convex beyond the surface of the joined plate.  The company website had a description of the manufacturing process and it told that the towers were rolled and powder welded.  I think it would take me a year to weld one of those seams with my own equipment and I`d have to mortgage my home to pay for the energy and all the stick electrode.  The resultant weld would look like crap and would have more flux entrapped within it than Carters has pills.  :(
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Billy

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Re: Interesting
« Reply #4 on: August 21, 2006, 02:15:25 AM »
The method I have been told about is termed "Micro fusion welding" and apparently is very suitable for repair of cast iron parts, and is done with an oxy actylene type torch.

Bill

hotater

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Re: Interesting
« Reply #5 on: August 21, 2006, 04:13:58 AM »
Billy---

"Micro Fusion" is a trade name for the metal build-up method that dkwflight mentioned.  I think that's the Eutectic term for it.  It's used on feed bowls and trolley tires and the journals of various shafts.  It's not for joining metals, only building up a homogenous layer that can be ground back to size.

"SubArc" is where a mild steel wire (or multiple wires) are automatically fed onto a moving surface or joints. The wire is the electrode and alloys and fluxes are applied in a deep layer from a funnel.  The excess alloy powders and fluxes are recycled back through the system.  The company where I worked made wear plate by subarc....A-36 mild plate welded with six, 1/8" wire welding heads all of them weaving 3X and interlocked.  Steel mill rolls are subarc welded then turned and ground to size.  It's not a maintenance or repair welder...strictly production.

That head CAN be repaired by TIG or MIG welding but it MUST have extensive preheating, preparation, welding, and post heat-treatment.  It's cheaper to buy another one.
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