sOLENOID is an electromagnetic device which produces magnetic field when current is passed through its coil windings. The term solenoid refers to a variety of transducer devices that convert electrical energy into kinetic energy. A basic solenoid structure consists of an electromagnetically inductive coil which is wound around a movable armature. In general, a solenoid’ s armature is also widely known as plunger and it is usually made from ferromagnetic materials like soft iron . The armature provides mechanical force for certain mechanisms which is proportional to the change in inductance of the coil with respect to the armature’s position and current flowing through the coil. The applied force will always move the armature in a direction that increases the coil ’s inductance. Basically, the armature will move into the solenoid when the coil windings are energized and thus create linear motion.Solenoid generally creates linear motion which is veryunique due to it s force – stroke characteristics. The forcevaries according to the stroke length which provides a wide range of energy band for the solenoid to operate. The range of energy band allows selection for t he user t o operate the solenoid with optimum performance and efficiency. Classically, there are two types of armaturetopologies, flat and conical. The flat-type solenoid generally provides large force in a range where the dis placement or stroke is small. Whereas the cone- type solenoid provides approximately flat-curve force characteristics regardless of the dis placement as compared t o flat face solenoid, this makes the conical solenoid effective in usage wit h a medium driving path(stroke). Solenoid can be push type or pull type depending on the application requirement. The angle of armature cone is decided based on the force and the stoke requirements for typical application to optimize the weight of the solenoid.Armature cone is decided based on the index number f or the typical application. Index number (i) is defined as the ratio of square root of the load force (lbf) to stroke (in) [1]. The relation between index number and armature cone angle; based on weight economy, is developed from practicalexperience [1].