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Anvils and swayback


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It's quite common to see sway back on (older, often wrought iron) anvils.

I'm very curious what exactly causes it and what factors have a play in it;

 

-energy (heat) of the anvil.

-material: wrought iron, steel top - cast steel - forged steel

-amount of pressure applied during forging

- Scale, it is hard and will put dents in your anvil face and hammer, no matter how hard you can get it.
may be this abrades the face away over time.
-Bubbles in the cast steel anvils.

 

What surprises me still, I have seen wrought iron anvils, and cast steel anvils (Kohlswa, KL, Brooks, UAT, DLC, Czech cast anvils (oldworldanvils), and more) all with 

sway back.
But I haven't found a Peddinghaus (forged steel) and a Refflinghaus anvil (cast steel) with sway back. Even though they have been in business for quite a long time.
Not as long as some wrought iron anvil producers, but steel, these two still exist today and still forge and cast anvils.


Is there anyone with a scientific and engineering background who could explain this to me?

Thank you very much for your input.

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Short of destructive testing of old anvils, I do not know of any sure way to test any of my harebrained ideas scientific theories on this. Not sure if X-rays would show a pattern of deformation in a swaybacked wrought iron anvil, but I will ask one of the NDE guys at work. (What is the point of having the only NDE associates degree program on the East Coast down the hall without getting something for free from them?)

 

For a while, I have wanted to try some different common welding rods on A36 steel plate, and see which ones would make a better anvil surface. Now I have another obsession to worry about. Thanks!

 

My personal observation is that anvils in commercial shops seem to have became much bigger in the US after wrought iron began to decline, and mild steel became more dominant. Even the mildest steel is worked at a lower heat, is more rigid, requiring bigger hammers and anvils to accomplish the same amount of work in a given stock size. I think that more force went into the anvil, which resulted in slow plastic deformation of the face.

 

 

 

On the other hand, Peter Ross says that the best feature of his anvil is that it has 1/16" of swayback from table to heel, and 1/32" from side to side, making it perfect for straightening items. It naturally compensates for springback.

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I believe mushrooming and swayback are simply signs of plastic deformation over time. Most anvils were rode hard and put up wet - so they slowly deformed - no different from struck tools or hammers. One person working over his lifetime might not cause noticeable wear but several generations of smiths and strikers can generate a lot of kinetic energy.

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The higher grade wrought iron anvils tend to deform more than the coarser grades--but they have less of a tendency to break.

 

Also the older ones often saw heavier work done on them---smiths started using powerhammers for heavier work instead of anvils and strikers as we come closer to modern times.

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Since you asked for a technical/engineer type to answer this question I'll chime in. For those that don't know, I am a degreed metallurgical engineer with 13 years of experience, the last 11 of which I've spent working as the plant metallurgist for the Clinton, WI facility of Scot Forge where we make open die forgings with starting weights up to 50,000 lbs.

 

I've been hand forging for the last 17 years. In that time, the only sway backed anvils I've encountered were those made from wrought iron with steel faces, though I don't doubt it could happen with steel anvils which were not heat treated correctly or were exposed to such high temperatures that the steel was annealed.

 

The cause of the sway back condition in wrought iron anvils is indeed due to plastic deformation. Wrought iron is generally pure iron with iron silicate slag inclusions, but usually no alloying elements. Pure iron has the strength of pure copper. So even though the anvil face is hardened steel, the body of a wrought anvil is extremely soft. This soft material lacks the strength to support the steel when subjected to very heavy blows and will deform over time leading to the sway backed condition. Steel anvils, whether cast of forged, have much higher strength when properly heat treated than wrought iron so they are much less likely to develop a sway back. Cast iron anvils, whether they have a steel face like Fishers or not, will not get a sway back because the cast iron does not have the ductility to plastically deform. It just chips or breaks. A couple of other things which could affect the formation of swayback are the thickness of the steel plate and how well that plate is forge welded to the wrought iron. Thin faces or poorly welded ones will likely have a more severe sway back than thick faced anvils with good welds.

 

Though scale is hard, it does not cause swayback, but it could cause dents or pits in the face. A casting flaw in a cast steel anvil probably would not be so large as to cause sway back but it could cause other problems such as pits if the voids were too close to the face. The temperature of the anvil during use probably does not have much affect on the development of sway back. Even if the anvil reaches a temperature of several hundred degrees, that will not significantly lower the force required to plasticaly deform the material beneath the face.

 

One thing to keep in mind about anvils and their use is that they were heavily used in industrial settings where production hand forging was done daily. In these settings, the anvils were exposed to a lot of heavy sledge work. Watch "Welding the Big Ring" on you tube and pay attention to what is happening in the background. You'll see a great example of that type of heavy work. That is the type of work that causes sway back. If you read through Practical Blacksmithing by MT Richardson you will find several examples describing re working of sway back anvils to make them flat again and you can see that mentioned in some of the advertising literature shown in Anvils In America by Postman. It seems that there was quite a call for reworking of anvils in years past which would suggest that sway back was common and occurred much more rapidly than we tend to think, again due to the continuous use of heavy sledges rather than by a lone smith swinging a hand hammer.

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Hi Patrick,

 

Wow, you gave some input! Thank you for the thorough answer. I have been asked earlier about this matter and only could say very unsure speculations.

BTW I has been wondering for some time now has anybody seen newer anvils with sway back? The smith in the next village has a minor one on his anvil: a 45 kg cast steel that he has used since the early 70's.

 

Thanks and bests:

 

Gergely

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Though scale is hard, it does not cause swayback, but it could cause dents or pits in the face. 

 

I am totally unqualified as a blacksmith (well I have a teachers certificate in Handicraft and Art) but I am not 100% with you on that.

 

The abrasive action of scale being scuffed backwards and forwards on the sweet spot for years could easily account for at least some of the hollow. If you just rub your hammer face in a heap of scale it comes up polished, polished = abrasion however fine the grit. Lots of fine polishing could easily account for the hollows in any hand anvil I have seen.

 

I guess the difference between wear and cold forging could be determined by whether the anvil below the face plate is wider at that point, the metal has got to go somewhere. If it is the wrought iron body that is deforming and so allowing the hard face plate to bend then the underside of the hard facing plate is not going to be straight. If the top plate is dished and the weld line straight that would indicate wear rather than deformation. It is very obvious on the power hammer pallets that they have mushroomed and been deformed by impact, but not as much by any means on hand anvils. 

 

The main part of the flattening on the bick of my anvil was certainly from deformation by impact even if some of it was also wear. The metal had definitely moved down and out around the sweet spot.

 

Alan

 

P.S. Having posted this I went and checked my anvil and sure enough could feel a slight fullness on either side in the area of the main hollow!  Still reckon scale abrasion could be responsible for some of it though. :)

 

Edited by Alan Evans
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Alan- You are right about the abrasive nature of scale. It certainly does result in wear on power hammer and press dies and no doubt could contribute to wear on anvil faces, but I would draw the same distinction you did between wear and deformation. The anvils I've owned and seen with sway back show the swelling you observed beneath the face. As far as wear is concerned, I actually think that the chipping of the face would contribute to more uneven work surface than wear from abrasion.

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Well, simply guessing, but besides plastic deformation and scale abrasion, wouldn't there of course be some wear in the sweet spot from striking it with a hammer? Not deforming it so much as gradually removing miniscule amounts of metal over time, however small? A few tens of thousands of strikes with a hammer has got to be at least as abrasive as say, one very fast pass with a flap disc.

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I don't think that will happen in normal use. There is hopefully not too much striking of the anvil surface with the hammer, there should actually only be the hot metal in contact…in which case I think you would be more likely to be adding metal to the anvil than take anything away.

 

I know what you mean about transfer though. With Stainless Steel you are meant to rack it on wood or plastic clad bearers so that there is no transfer/contamination by contact with steel.

 

I am aware that there is a bit of drag and galling on my 3cwt hammer pallets when I am forging SS. As you know similar metals can weld together under pressure. My flat pallets originally had a dovetail slot which has been filled in with a piece of steel, every now and then I have to reweld the joints with 312 rod which is stainless and this grabs at the stainless workpiece and is a bit of a pain to say the least.

 

On my hydraulic press hot punches made from Progen steel after a few holes there is quite a build up around the tip. At first I thought this was mushrooming from the action of pushing  through the hot bar, but I quickly realised that the punch was not getting any shorter, and that the build up was layers of the work piece steel which were just being welded to the punch tip.

 

Alan

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