Filling Factories in the United Kingdom

A Filling Factory was a munitions factory which specialised in filling various munitions, such as: bombs, shells, cartridges, pyrotechnics, screening smokes, etc. In the UK, in both world wars, the majority of the employees were women.

In the UK, in World War I, such a factory belonging to the Ministry of Munitions was known as a National Filling Factory.

In the UK, in World War II, such a factory belonging to the Ministry of Supply was known as a Royal Filling Factory (RFF), or a Royal Ordnance Factory (ROF). In terms of organisation, they were part of the Royal Ordnance Factory organisation.

Particularly, in World War II, the filling of screening smokes and other pyrotechnic devices was also carried out by fireworks manufacturers; parts of this article do not apply to these fireworks filling factories.

The Filling Factory's raw materials, such as TNT, RDX, or propellants, such as cordite, were manufactured in National Explosives Factories (World War I) or Explosive ROFs (World War II) and transported, by railway trains, to the Filling Factories for filling into munitions, produced at other plants.

High-explosives, such as TNT, had to be heated to melt them and the liquid was poured hot into heated shell cases. Care had to be taken to ensure that there were no voids in the poured explosive charge as this could lead to the shell detonating in the gun barrel during firing.

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