A fuze is a device that detonates a munition‘s explosive material under specified conditions. In addition, a fuze will have safety and arming mechanisms that protect users from premature or accidental detonation. For example, an artillery fuze’s battery is activated by the high acceleration of cannon launch, and the fuze must be spinning rapidly before it will function. “Complete bore safety” can be achieved with mechanical shutters that isolate the detonator from the main charge until the shell is fired.
A fuze may contain only the electronic or mechanical elements necessary to signal or actuate the detonator, but some fuzes contain a small amount of primary explosive to initiate the detonation. Fuzes for large explosive charges may include an explosive booster.
Fuze categorization by munition type
The situation of usage and the characteristics of the munition it is intended to activate affect the fuze design e.g. its safety and actuation mechanisms.
Artillery fuzes are tailored to function in the special circumstances of artillery projectiles. The relevant factors are the projectile’s initial rapid acceleration, high velocity and usually rapid rotation, which affect both safety and arming requirements and options, and the target may be moving or stationary.
Artillery fuzes may be initiated by a timer mechanism, impact or detection of proximity to the target, or a combination of these.
Hand grenade fuze
Requirements for a hand grenade fuze are defined by the projectile’s small size and slow delivery over a short distance. This necessitates manual arming before throwing as the grenade has insufficient initial acceleration for arming to be driven by “setback” and no rotation to drive arming by centrifugal force.
Aerial bomb fuze
Aerial bombs can be detonated either by a fuze, which contains a small explosive charge to initiate the main charge, or by a “pistol”, a firing pin in a case which strikes the detonator when triggered. The pistol may be considered a part of the mechanical fuze assembly.
The main design consideration is that the bomb that the fuze is intended to actuate is stationary, and the target itself is moving in making contact.
Naval mine fuze
Relevant design factors in naval mine fuzes are that the mine may be static or moving downward through the water, and the target is typically moving on or below the water surface, usually above the mine.