What is A Solenoid Coil?

Figure 1: Solenoid coils.
(Go to Okmarts and pick the Solenoid coil you need)

1. Overview

The solenoid coil generally refers to the inductive coil, which is wound on the insulating tube by the wires. The wires are insulated from each other. The insulating tube are hollow and contain iron core or magnetic particle core. The inductance of the coil is expressed in L, and the units are Henry (H), Millihenry (MH) and Microhenry (μ H), 1H=10^3mH=10^6 μ H.

2. Working Principle

Solenoid coil is a device that works by using the principle of electromagnetic induction. When a current flows through a wire, a electromagnetic field will be generated around the wire, and the wire itself will induce the wire within the range of the electromagnetic field. The effect on the wire itself that generates the electromagnetic field is called "self inductance", that is, the changing current generated by the wire itself generates a changing magnetic field, which further affects the current in the wire; the effect on other wires within the range of the electromagnetic field is called "mutual inductance".

Figure 2: Solenoid coil.

The electrical characteristics of the solenoid coil are opposite to those of the capacitor. When the high-frequency signal passes through the solenoid coil, it will encounter great resistance which make it difficult to pass through; while the resistance that the low-frequency signal passing through is very small, that is, the low-frequency signal can pass through it easily. The resistance of the solenoid coil to DC is almost zero.

Capacitance and inductance will present a resistance to the flow of electrical signals in the circuit. This resistance is called "impedance". The impedance of solenoid coil to the current signal is from the self inductance of the coil. Solenoid coil is sometimes referred to as "inductance" or "coil", which is represented by the letter "L". When winding an solenoid coil, the number of turns is generally called the "number of windings".

3. Classification

1.Classified by inductance form: fixed inductance and variable inductance.

2.Classified by the nature of the conducting magnet: air core coil, ferrite coil, iron core coil and copper core coil.

Figure 3: Air core coil.

3.Classified by the nature of work: antenna coil, oscillation coil, choke coil, notch coil and deflection coil.

Figure 4: Single layer coil (left) and multi-layer coil (right).

4.Classified by winding structure: single layer coil, multi-layer coil, honeycomb coil, close wound coil, inter wound coil, tire free coil, honeycomb coil and random wound coil.

4. Dispensing of The Solenoid Coil

The dispensing of inductance coil is an automatic glue dispensing operation aimed at the gap between solenoid coil and base plate, so as to cement the coil. Both sides need to carry out dispensing, which requires four-axis dispensing operation based on the original three-axis dispensing manipulator to ensure the same amount and effect of dispensing on both sides.

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