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driving bands
- Thread starter leeski
- Start date
From the book "88 FLAK and PAK" from Profile Publications (1976) ISBN 0853830924, by P chamberlain and T Gander, they say that with the changes to diglycol and later Gudol propellants and the change to sintered iron bands, that the Germans were getting barrel life up to 10,000 rounds.
The U.S. has used sintered iron bands for a number of projectiles ove rthe years. The T91 90mm HE, TP projos for the 152mm gun launcher, and some flechette rounds.
The U.S. has used sintered iron bands for a number of projectiles ove rthe years. The T91 90mm HE, TP projos for the 152mm gun launcher, and some flechette rounds.
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I studied my book some more, and at the beginning of the section on Barrel development, it says that in 1933 using chordite and HE shells with copper rotating band, the FlaK 18 had a barrel life of 900 rounds, so by changing propellants and rotating bands they got it to 10,000 rounds!
A very scientific and meticulous people those Germans!
A very scientific and meticulous people those Germans!
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Hazord,
There must be something more to it, with a greater than 10 fold increase in barrel life the world and his dog would be using sintered iron driving bands. Both the US and UK continue to use copper driving bands.
Regards
TimG
The following is an extract from Textbook of Ammunition - Projectiles 1957(?)
10.5. Materials:—The normal material for orthodox British driving bands is copper of a high degree of purity usually conforming to specification BS/STA/13. It has a high heat conductivity, a relatively low melting point, and, in the partially worked condition as in the completed driving band, is relatively soft. It possesses certain disadvantages as a driving band material in that, at velocities of the order of 2,000 f.s., bore friction apparently causes the band surface to melt with a consequent rapid loss of working copper. With high velocity rounds this leads to a tendency to complete band failure in the latter part of shot travel. In high performance guns also, the tendency to band failure reduces the effectiveness of a copper band as a centring device. These effects can be mitigated to an extent by an increase in the cross-sectional area of the band, which may, however, result in excessive band pressure, and will in any case involve a large consumption of copper. In high performance guns copper is therefore an uneconomical material for driving bands, and in very high velocity guns may be entirely unsuitable.
In the Second World War a number of belligerents, owing to a shortage of copper, introduced alternative materials, in particular sintered iron. Sintered iron is produced from iron powder by pressing and heating, the physical properties of the material being controllable over a wide range by selection of the conditions of production. Depending upon the pressure, the temperature, the degree of sub-division, and also the nature of the iron, the product is to a greater or lesser extent spongy in texture, has a bulk density less than that of solid iron, and is in general soft and readily deformed by pressure. It also has a tendency to brittleness, which decreases with increasing solidity.
There is some evidence that, with sintered iron bands and cool propellants, wear at C of R may be appreciably reduced, but abrasive wear throughout the bore, particularly in medium and H.V. guns, may be increased. This latter effect is liable to cause muzzle enlargement with a consequent loss of accuracy, and this might become as important a limiting factor on barrel life with cool propellants as wear at C. of R. It is possible, however, to achieve some reduction in the effects of abrasion by widening the lands and deepening the grooves. Sintered iron has no tendency to be deposited on the bore of the gun, but its low tensile strength prevents its use in large calibre guns owing to break-up under high centrifugal force. As sintered iron has a higher melting point than copper and can be made stronger in shear, it may be possible to use a smaller width of band, which will reduce the band pressure.
There must be something more to it, with a greater than 10 fold increase in barrel life the world and his dog would be using sintered iron driving bands. Both the US and UK continue to use copper driving bands.
Regards
TimG
The following is an extract from Textbook of Ammunition - Projectiles 1957(?)
10.5. Materials:—The normal material for orthodox British driving bands is copper of a high degree of purity usually conforming to specification BS/STA/13. It has a high heat conductivity, a relatively low melting point, and, in the partially worked condition as in the completed driving band, is relatively soft. It possesses certain disadvantages as a driving band material in that, at velocities of the order of 2,000 f.s., bore friction apparently causes the band surface to melt with a consequent rapid loss of working copper. With high velocity rounds this leads to a tendency to complete band failure in the latter part of shot travel. In high performance guns also, the tendency to band failure reduces the effectiveness of a copper band as a centring device. These effects can be mitigated to an extent by an increase in the cross-sectional area of the band, which may, however, result in excessive band pressure, and will in any case involve a large consumption of copper. In high performance guns copper is therefore an uneconomical material for driving bands, and in very high velocity guns may be entirely unsuitable.
In the Second World War a number of belligerents, owing to a shortage of copper, introduced alternative materials, in particular sintered iron. Sintered iron is produced from iron powder by pressing and heating, the physical properties of the material being controllable over a wide range by selection of the conditions of production. Depending upon the pressure, the temperature, the degree of sub-division, and also the nature of the iron, the product is to a greater or lesser extent spongy in texture, has a bulk density less than that of solid iron, and is in general soft and readily deformed by pressure. It also has a tendency to brittleness, which decreases with increasing solidity.
There is some evidence that, with sintered iron bands and cool propellants, wear at C of R may be appreciably reduced, but abrasive wear throughout the bore, particularly in medium and H.V. guns, may be increased. This latter effect is liable to cause muzzle enlargement with a consequent loss of accuracy, and this might become as important a limiting factor on barrel life with cool propellants as wear at C. of R. It is possible, however, to achieve some reduction in the effects of abrasion by widening the lands and deepening the grooves. Sintered iron has no tendency to be deposited on the bore of the gun, but its low tensile strength prevents its use in large calibre guns owing to break-up under high centrifugal force. As sintered iron has a higher melting point than copper and can be made stronger in shear, it may be possible to use a smaller width of band, which will reduce the band pressure.
TimG,
Thanks for posting the info. It is very interesting. The section of my book that deals with barrel Improvements speaks about how the greatest wear was in the forcing cone area at the mouth of the chamber. From 1933 through 45, we are talking 12 years that they could have improved the steel in front of their chambers, tinkered with propellant temperatures and pressures, and mixed up their own chemistry for the bands.
The advantage of powdered metal being sintered into a band, allows them to mix powders of different metals that could not normally be combined by melting. The U.S. used strips of lead in the propellant bags of large guns, to reduce or eliminate coppering of the rifling from copper rotating bands. Lead is also used in steels to make them "free machining" for more efficient machining. I haven't seen any chemistry on the German sintered iron bands to know what they did.
Maybe some of our other members have been privy to better technical data.
Thanks for posting the info. It is very interesting. The section of my book that deals with barrel Improvements speaks about how the greatest wear was in the forcing cone area at the mouth of the chamber. From 1933 through 45, we are talking 12 years that they could have improved the steel in front of their chambers, tinkered with propellant temperatures and pressures, and mixed up their own chemistry for the bands.
The advantage of powdered metal being sintered into a band, allows them to mix powders of different metals that could not normally be combined by melting. The U.S. used strips of lead in the propellant bags of large guns, to reduce or eliminate coppering of the rifling from copper rotating bands. Lead is also used in steels to make them "free machining" for more efficient machining. I haven't seen any chemistry on the German sintered iron bands to know what they did.
Maybe some of our other members have been privy to better technical data.
I've just been reading a post war German account of their development of the 88. They state that the utilisation of sintered iron and cooler propellants had a marked increase on barrel life - unfortunately they don't quote any figures. Sadly for them, there was a lot of indecision regarding whether or not to use copper or iron and as a result at the start of the war they had a lot of copper banded projectiles stockpiled. Unfortunately for them. they had already discovered that you shouldn't use sintered banded projectiles in a barrel that has already been used with copper banded projectiles as the performance is seriously degraded.
Regards
TimG.
Regards
TimG.
Cordite
From an engineering point of view,a soft iron band in a steel barrel would wear very well, in early british guns,the biggest cause of barrel erosion was from use of the earlier types of cordite, later types significantly reduced this problem. Cordite MD was later replaced with cordite SC. Any band comparison would have to use the same propellant type to be fair.
From an engineering point of view,a soft iron band in a steel barrel would wear very well, in early british guns,the biggest cause of barrel erosion was from use of the earlier types of cordite, later types significantly reduced this problem. Cordite MD was later replaced with cordite SC. Any band comparison would have to use the same propellant type to be fair.