wire wound barrel cost

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Nodeo-Franvier
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wire wound barrel cost

#1

Post by Nodeo-Franvier » 08 Dec 2020, 16:28

Wikipedia said that QF 18 pounder wire wound barrel is cheaper than a built up barrel, however another source said that Build up gun are much cheaper than their wire wound counterparts.
In the end which method is more economical?

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Terry Duncan
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Re: wire wound barrel cost

#2

Post by Terry Duncan » 12 Dec 2020, 19:01

This is a very complex question that has no real definitive answer, rather it depends on what exactly the gun is used for and the preferences of the force using the gun. My knowledge comes from the naval guns, but the same is almost certainly true for lighter guns too.

Wire wound guns take a lot longer to make and are more expensive because of this, but they also tend to last longer in action before barrel droop reaches levels than lead to unacceptable accuracy. If it is possible to replace the barrels quickly or in situations where limited use is expected before it is possible to replace the barrel, then a built up barrel is perfectly acceptable. However, if extended deployment away from possible replacement barrels is expected, then a wire wound barrel works best. Think of how the British thought of global deployment for their ships and expected they may be a long time between refits, against how the Germans or Italians planned to deploy and use their ships.

Another consideration is that wire wound guns are a rather niche product, whilst a built up barrel can be produced much easier.


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jluetjen
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Re: wire wound barrel cost

#3

Post by jluetjen » 12 Dec 2020, 19:32

This is more of a manufacturing technology question. A couple of thoughts (although I'm not involved in anything like this), I've spent years in manufacturing. It would be an interesting question to research further. The best place to start would be to track down the company(s) or sites that manufactured this weapon and see what their process was. I also found this interesting document from the US Army's review of Soviet artillery manufacturing that might provide some insight.

1) Economical is a vague term. It could mean cheaper to manufacture, or cheaper to manufacture with acceptable yields. It could also reflect the total cost of ownership of the piece (i.e. Barrel life). In this case the manufacturer appears to have been Bethlehem Steel.

2) Looking at this site they say...
The 18-pdr used a wire-wound barrel. Under that method, construction starts with a thin-walled bore tube, over which the gun-makers wrap wire under pressure. Over the wire is an exterior jacket. Fifteen layers of .04 x .25 inch wire reinforced the breech end of the gun. This process had great advantages in economy and allowed gunmakers to spot flaws in the metal rather easily. Later versions of the 18-pdr, starting with the Mk. II, featured barrels produced with hydrostatic pressure, to speed production. But Bethlehem used the original wire-wound construction technique.
This quote suggests that the economy was in manufacturing, specifically the yields. Given that the manufacturer could spot flaws in the wire (either prior to winding, or else while it is being wound -- and in either case either fix the problem or restart the assembly), it minimizes the yield loss in the manufacturing process. This is inspite of the potentially longer amount of time that that takes to complete the wire winding process. In a casting process, you have to do the full process, and then if you're lucky you might spot a flaw in the work in process, which requires scrapping all of the work done up to that point since it's usually not possible to repair castings. Often the issues might appear in post-cast machining processes, so add some of this process to the scrap costs too. So the incremental nature of wire-winding the barrel provides less scrap in the work-in-process. This of course could (but doesn't necessarily have to) translate into a lower price for the customer.

Another thing to consider it the quality control of the wire. Due to the nature of manufacturing the wire, the manufacturer may be able to control the material quality better since it is most likely manufactured in a more continuous process, potentially drawn or rolled. So this may make the material stronger than the cast equivalent, and thus may then require less material.

Really, you'd have to do a cost comparison, as well as some yield calculations to understand the way that this might work out. By the time that you get done, you might be a competent cost accountant!

That might get you started.

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