Types of metal detection coils are not just technical components, but rather the main factor that determines the device’s performance and efficiency in detecting metals of various shapes and sizes. Metal detection coils are one of the most important basic elements that any metal detection device relies on. These coils are the element responsible for creating magnetic fields and interacting with buried metals, allowing the metal detectors to accurately locate them. Each type of coil has distinct characteristics that make it suitable for specific applications, whether it is searching for coins or jewelry or even for heavy industrial uses.
What are metal detection coils?
They are the main component that generates the magnetic field inside metal detectors. These coils are designed to be sensitive to changes in the magnetic field resulting from the presence of metals underground or in objects. When a conductive metal approaches the coil, an eddy current is generated inside the metal, leading to noticeable changes in the surrounding magnetic field, and these changes are detected by the device.
Detection coils are used in many applications, from prospecting for precious metals such as gold, to industrial uses such as detecting metal objects buried in concrete or soil, as well as in security fields to detect weapons. Metal detection coils vary in design and function, including circular coils, bi-directional coils, and coils designed for deep detection.
How metal detection coils work
Types of Metal Detection Coils
The mechanism of operation of metal detectors depends mainly on the types of metal detection coils and their role in generating magnetic fields to detect metal objects. The device begins by producing an alternating electric current through the primary coil, which leads to the generation of an oscillating magnetic field. When a metal object approaches, the field causes eddy currents to be produced inside this object, which generates an opposite magnetic field.
The secondary coil in the device senses this change and signals are sent to the electronic system to analyze them and determine the type or size of the metal. The devices use different techniques to measure changes in frequencies resulting from interaction with metals. Some devices rely on high frequencies to detect small or low metals to search at greater depths.
Types of metal detection coils in terms of manufacturing
Types of metal detection coils in terms of manufacturing vary based on the materials used and designs that affect their performance in identifying metals, including:
Dual coils
- Made of two overlapping coils that create a wide magnetic field.
- Copper wires are used coated with an insulating material such as plastic to withstand environmental conditions.
- They are characterized by the ability to work in mineral-rich soils while reducing interference.
Interlaced coils
- Consist of two precisely centered circular coils.
- Made of copper covered with a protective layer such as ceramic or polymers.
- Effective for surface search and accurately identifying small metal objects.
Deep search coils
- A circular coil provides wide coverage and is suitable for detecting heavy metals at depth.
- Relies on thick wires to withstand high electrical pressure.
- Used for prospecting for precious metals such as gold in the ground.
Grid coils
- Consist of a complex network of wires to provide superior sensitivity.
- Relies on advanced fibers that are resistant to corrosion and harsh conditions.
- Effective for detecting very small grains of metals.
Compound coils
- Combine multiple designs to provide balanced performance.
- Made of copper reinforced with fiberglass to provide strength and light weight.
- Suitable for a wide range of uses from surface search to deep prospecting.
Types of metal detection coils by size
Types of metal detection coils by size vary to suit different uses, from surface detection of small objects to deep prospecting for heavy metals. The choice of size depends on the purpose of use and the nature of the environment in which the search is conducted, as follows:
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Small coils (up to 15 cm)
- Used to detect very small metal objects such as coins or jewelry.
- Ideal for areas with high mineral soil or tight spaces.
- It also provides high accuracy and better pinpointing of the location of metals.
- Reduces interference from electromagnetic interference.
Medium coils (16 to 25 cm)
- Balance between accuracy and coverage, making them suitable for general searching.
- Effective in detecting medium-sized metal objects such as old tools or large coins.
- Provides wider coverage than small coils while maintaining reasonable accuracy.
- Suitable for individuals searching for metals in parks or beaches.
Large coils (greater than 26 cm)
- Dedicated to detecting heavy metals and large objects buried at great depths.
- Used in industrial prospecting and searching for buried treasures.
- Provides wide coverage, making it effective in searching in open areas.
- Able to reach depths beyond the capacity of small and medium coils.
The most important features of metal detection coils
The types of metal detection coils are characterized by a set of characteristics that make them essential tools for detecting metals in many fields, and the most important of these features are the following:
- They are characterized by their ability to accurately identify metals, as they can distinguish between different types of metals such as: iron, gold, and copper.
- They are used in various fields including airport security to detect weapons, archaeological excavation, and the mining field to discover natural resources such as raw gold and precious metals.
- The coils are designed to work efficiently in different environments such as desert soil or rocky areas, making them ideal for searching in harsh conditions.
- These coils work very quickly, as they respond immediately upon passing over a metal object, ensuring time savings during search operations.
- Most coils come in a comfortable and lightweight design for easy carrying And use it for long periods.
FAQs
Can search coils be changed for metal detection?
Yes, search coils can be changed provided that they are compatible with the detector.
What is the importance of different metal detection coils?
The importance of coils varies according to their design and size, as each type allows them to adapt to different search environments, such as surface detection or deep excavation, and helps in identifying metals with high accuracy.
How do you test a metal detector coil?
It can be tested by placing a known piece of metal in front of it and moving it at different distances, and observing the accuracy and response of the signal. You can also review the connections and test the electrical resistance.
What is a DD coil on a metal detector?
It is a type of search coil that is characterized by wider coverage and better accuracy in distinguishing between metals. It is especially used in mineral soil or places with high interference.
