What Is an Electromagnet Holding Solenoid?

An electromagnet holding solenoid, also known as an electro holding magnet, is a device designed to securely hold ferromagnetic parts using electromagnetic force. It consists of a steel housing and an internal coil. When energized, the coil generates a magnetic field that holds the metal object in place—this is commonly referred to as an “energize-to-hold” mechanism.

Dr. Solenoid offers two types of DC 12V or 24V electromagnet holding solenoids:

Switched-ON to Hold (energize to attract and hold)

Switched-OFF to Hold (de-energize to release)

Our Product Range

We supply both round and rectangular solenoid electromagnets, available in DC 12V or 24V, with size options ranging from Ø8 mm to Ø100 mm, and holding forces from 2N to 2400N.
Pricing is negotiable based on order quantity.

Key Advantages

✦ High Holding Force
Electromagnets offer strong clamping power, enhanced by durable nickel plating for resistance in demanding applications.

✦ Easy ON/OFF Control
Magnetic force is activated or deactivated with a simple electrical current, making it highly energy-efficient and user-friendly.

✦ Remote Operation
Since the magnet is controlled via electric current, it can be safely operated from a distance—minimizing risk and improving operational safety.

✦ Flexible Mounting Options
Available in multiple sizes and shapes, our electromagnets can be mounted to fit various systems and structures.

 AS 6035 Best electro holding magnets DC 24 V strong force from Dr solenoid

Structure and Working Principle

The electro holding magnets is an electromagnetic fixture that fixes the workpiece by the suction force generated by the solenoid coil inside after the electromagnetic coil is energized. The The electro holding magnets consists of several parts such as the iron core, solenoid coil, panel and bobbin.   The electro holding magnets composed of the solenoid coil and the iron core is the main part of the unit.  The electro holding magnets is different due to the difference in design methods or materials used, and is also constantly developing and improving. The electro holding magnets is used on the grinder instead of using splints and bolts to fix the workpiece being ground. Such an The electro holding magnets is relatively simple and can only fix flat workpieces. This is the traditional electromagnets, and its application has great limitations. With the development of industry, Solelnoid enterprises have an increasing demand for electromagnetic tools, and the requirements are getting higher and higher, prompting people to continuously update the application of the electro holding magnets.

Electro holding magnets style.

Generally, there are two styles of circular suction cup electromagnets, ordinary style (i.e., power on, power off, release); holding style (power on, release, power off, just the opposite of the ordinary style) The suction surface can also be made into various shapes according to actual needs, such as arc shape, V shape, etc.

Product principle: When the solenoid coil inside is energized, magnetic energy is generated, the housing and the middle iron core are magnetized, and then a magnetic field loop is generated, so the suction cup product must rely on the suction surface to work. At a distance of 0mm, the suction cup electromagnet has a strong force despond on different size.

Advantages: Advantages of suction cup electromagnets: 0mm distance suction force is large, which is different from the concept of frame and round tube electromagnets, and the force generated is also different; in the case of spacing, the attenuation force is also different, 0-5mm is attenuated by 65%, 5-10mm is attenuated by 85%, and the force generated at different distances is also different; in terms of installation, it can be designed according to requirements to meet the application of various occasions.

The electro holding magnets has been improved in a series of ways to meet the needs of production. The electromagnetic suction cup is optimized and designed according to customer requirements to solve the serious problems of fast heating, large residual magnetism, and uneven suction surface. The suction force and volume of the circular suction cup type electromagnet product can be customized according to the required requirements. Products of different sizes use different power and functions.

 What is a small round electric holding electromagnet

small round electric holding electromagnet is a permanent holding electromagnet built in a small magnet inside. It features power on to release and power off to hold during operation.

 Part 1 ： The structure of 2015 DC Lifting electromagnet

• 1.1： Iron core: usually located in the middle of the coil, it is an important part of the electromagnet to generate magnetic force. It is made of soft magnetic materials and can be             magnetized to enhance the magnetic field when powered on.
• 1.2：Solenoid Coil: it is made of copper wire, it is the source of the magnetic field. When DC current is passed through, a magnetic field will be generated around it. The larger the          current and the more turns of the coil, the stronger the magnetic field.
• 1.3: Panel: it is usually made of magnetic conductive material, located on the adsorption surface of the electromagnet, it can guide the magnetic lines to be concentrated, making
•       the adsorption force more concentrated and effective, and increasing the suction force on the workpiece.
• 1.4 Bottom housing: it is the role of supporting and protecting the internal iron core, solenoid coil and other components. It is generally made of solid materials such
•       as carbon steel plates to ensure the overall structural strength of the electromagnet.1.5 Electric wire: it is used to connect an external power supply, input current to the                    solenoid coil, and enable the electromagnet to work normally.
•  
• Part 2 : Working Principle
• Based on the principle of electromagnetic induction, when current passes through the solenoid coil of the suction cup electromagnet, a magnetic field is generated around the solenoid coil, which magnetizes the iron core, and the magnetized iron core further enhances the magnetic field strength. At this time, if a magnetic workpiece approaches the panel of the suction cup electromagnet, the workpiece will be tightly sucked under the action of the magnetic field force. When the current of the coil is cut off, the magnetic field disappears quickly, the magnetism of the iron core also disappears, the workpiece loses suction and separates from the suction cup, thus achieving demagnetization.

 What is a Reverse Permanent Lifting electromagnet?

The direction of the magnetic field lines depends on the direction of the current flowing through the solenoid coil of the electromagnet.  A "reverse permanent lifting electromagnet" isn't a standard, widely - known term. a Reverse Permanent lifting electromagnet is a device that uses an electromagnetic field to lift ferromagnetic materials like iron and steel

Reverse Permanent Lifting electromagnet is to Reversing the direction of the electric current reverses the direction of the magnetic field lines which reverses the polarity of the magnet.

What are the advantages of using a reverse permanent lifting electromagnet compared to other types of magnets? 

1. Enhanced control:

- A reverse permanent lifting electromagnet combines the properties of a permanent magnet and an electromagnet. The ability to reverse the magnetic field provides more precise control over the lifting and releasing of objects. For example, in a factory setting, it can be used to pick up and release small metal parts with greater accuracy than a simple permanent magnet, which has a constant magnetic field and may not release the parts as easily.

2. Energy efficiency:

- Once the object is initially attracted using the combined magnetic field (permanent and electromagnetic), the power to the electromagnet can be reduced or adjusted. The permanent magnet component helps to maintain the hold on the object, saving energy compared to a traditional electromagnet that requires a continuous supply of a relatively high current to maintain the lifting force.

3. Versatility:

- It can handle a wider range of ferromagnetic materials. The adjustable magnetic field strength and direction allow it to work with different shapes, sizes, and weights of objects. For instance, it can be used to lift both heavy steel plates in a construction site and tiny metal components in an electronics manufacturing plant. In contrast, a simple permanent magnet may not have the flexibility to handle such a diverse range of objects effectively due to its fixed magnetic strength and polarity.

4. Safety:

- The reverse function can enhance safety. In a situation where the object needs to be quickly released, such as in a conveyor - based sorting operation, the ability to reverse the magnetic field ensures a reliable release mechanism. This can prevent jams or accidents caused by objects not being properly released, which is an advantage over other type

AS 3257 Tubular Solenoids

AS 3257 tubualr solenoids are compact, high-performance actuators designed for precise linear motion control in demanding applications such as automation systems, machine tools, medical devices, and packaging machinery.

Available in pull (R32x57) and push (RP32x57) configurations, they offer flexibility for a variety of mechanical movements. With a long stroke of up to 20 mm, these solenoids deliver an increasing force characteristic for efficient and reliable actuation.

Key features include:

Base mounting with a base seat design, screw mounting holes, and a shakeproof washer for secure and stable installation.

Class B coil insulation with UL-rated materials for enhanced durability and safety.

Coil options for continuous or intermittent duty operation.

Reliable operation in any orientation without performance loss.

Customizable force, DC power source, and stroke length options to meet specific application needs.

With rugged construction and versatile mounting, the AS 3257 series is engineered to withstand harsh industrial environments while delivering consistent, repeatable performance.

 Introduction of AS 0925 New Design Linear Solenoid Actuator 

A tubular solenoid is an electromechanical device that converts electrical energy into mechanical motion. The following is a detailed introduciton :

Linear Solenoid Actuator Structure

Solenoid Coil: It consists of a copper wire coil, usually wound around a platic bobbin in the shape of a tube. The coil is often made of copper wire to ensure good electrical conductivity.

Plunger: Inside the coil-core assembly, there is a movable plunger, typically crafted from a magnetic material like soft iron2. The plunger can move axially within the tube.

Working Principle

Magnetic Field Generation: When an electric current passes through the solenoid coil, it generates a magnetic field according to the principle of electromagnetism. The magnetic field lines are concentrated inside the tube, creating a relatively strong magnetic field environment.

Plunger Movement: The magnetic field exerts a force on the plunger. In a pull solenoid, when the coil is energized, the plunger is drawn into the coil; in a push solenoid, the plunger is pushed out of the coil. This movement is used to perform various mechanical tasks.

Types Of Linear Tubualr Solenoid

Push Tubular Solenoid: When energized, it pushes the plunger out of the coil. It is typically used in applications where a component needs to be moved away from the solenoid, such as propelling a ball in a pinball machine2.

Pull Tubular Solenoid: It pulls the plunger into the coil when powered on. They generally have a longer stroke length and are more commonly used, for example, in door locks to pull the latch into place2.

Linear Solelnoid Actutator Applications

Automotive Industry: Used in power door locks, automatic transmissions, and starter motors2.

Healthcare Sector: Play a vital role in medical devices such as ventilators and patient beds2.

Industrial Automation: Employed in assembly lines, robotic systems, and sorting machines2.

Home Appliances: Found in washing machines, dishwashers, and refrigerators to control water flow and other mechanical operations2.

Safety Systems: Utilized in fire suppression systems to control the release of fire-extinguishing substances and in anti-lock braking systems in vehicles to modulate brake fluid pressure.

 Part 1 : Key point requirement for keyboard testing device Solenoid  

1.1 Magnetic field requirements

In order to effectively drive keyboard keys, keyboard testing device Solenoids need to generate sufficient magnetic field strength. The specific magnetic field strength requirements depend on the type and design of keyboard keys.  Generally speaking, the magnetic field strength should be able to generate sufficient attraction so that the key press stroke meets the trigger requirements of the keyboard design. This strength is usually in the range of tens to hundreds of Gauss (G).

1.2 Response speed requirements

The keyboard testing deviceneeds to test each key quickly, so the response speed of the solenoidis crucial. After receiving the test signal, the solenoid should be able to generate sufficient magnetic field in a very short time to drive the key action. The response time is usually required to be at the millisecond (ms) level. the rapid pressing and releasing of the keys can be accurately simulated, thereby effectively detecting the performance of the keyboard keys, including its parameters without any delay.

1.3 Accuracy requirements

The action accuracy of the solenoidis crucial for accurately。The keyboard testing device. It needs to accurately control the depth and force of the key press. For example, when testing some keyboards with multi-level trigger functions, such as some gaming keyboards, the keys may have two trigger modes: light press and heavy press. The solenoid must be able to accurately simulate these two different trigger forces. Accuracy includes position accuracy (controlling the displacement accuracy of the key press) and force accuracy. The displacement accuracy may be required to be within 0.1mm, and the force accuracy may be around ±0.1N according to different test standards to ensure the accuracy and reliability of the test results.

1.4  Stability requirements

Long-term stable operation is an important requirement for the solenoidof the The keyboard testing device. During the continuous test, the performance of the solenoidcannot fluctuate significantly. This includes the stability of the magnetic field strength, the stability of the response speed, and the stability of the action accuracy. For example, in large-scale keyboard production testing, the solenoid may need to work continuously for several hours or even days. During this period, if the performance of the electromagnet fluctuates, such as the weakening of the magnetic field strength or the slow response speed, the test results will be inaccurate, affecting the evaluation of product quality.

1.5  Durability requirements

Due to the need to frequently drive the key action, the solenoidmust have high durability. The internal solenoid coils and plungermust be able to withstand frequent electromagnetic conversion and mechanical stress. Generally speaking, Keyboard testing device solenoid need to be able to withstand millions of action cycles, and in this process, there will be no problems that affect performance, such as solenoid coil burnout and core wear. For example, using high-quality enameled wire to make coils can improve their wear resistance and high temperature resistance, and choosing a suitable core material (such as soft magnetic material) can reduce the hysteresis loss and mechanical fatigue of the core.

Part 2 :. Structure of keyboard tester solenoid

2.1 Solenoid Coil

• Wire material: Enameled wire is usually used tomakethe solenoid coil. There is a layer of insulating paint on the outside of the enameled wire to prevent short circuits between the solenoid coils. Common enameled wire materials include copper, because copper has good conductivity and can effectively reduce resistance, thereby reducing energy loss when passing current and improving the efficiency of the electromagnet.
• Turns design: The number of turns is the key affecting the magnetic field strength of the tubular solenoid for Keyboard testing device Solenoid. The more turns, the greater the magnetic field strength generated under the same current. However, too many turns will also increase the resistance of the coil, leading to heating problems. Therefore, it is very important to reasonably design the number of turns according to the required magnetic field strength and power supply conditions. For example, for a Keyboard testing device Solenoidthat requires a higher magnetic field strength, the number of turns may be between hundreds and thousands.
• Solenoid Coil shape: The solenoid coil is generally wound on a suitable frame, and the shape is usually cylindrical. This shape is conducive to the concentration and uniform distribution of the magnetic field, so that when driving the keyboard keys, the magnetic field can act more effectively on the driving components of the keys.

2.2  Solenoid Plunger 

• Plungermaterial: The plungeris an important component of solenoid, and its main function is to enhance the magnetic field. Generally, soft magnetic materials such as electrical pure carbon steel and silicon steel sheets are selected. The high magnetic permeability of soft magnetic materials can make it easier for the magnetic field to pass through the core, thereby enhancing the magnetic field strength of the electromagnet. Taking silicon steel sheets as an example, it is a silicon-containing alloy steel sheet. Due to the addition of silicon, the hysteresis loss and eddy current loss of the core are reduced, and the efficiency of the electromagnet is improved.
• Plungershape: The shape of the core usually matches the solenoid coil, and is mostly tubular. In some designs, there is a protruding part at one end of the plunger, which is used to directly contact or approach the driving components of the keyboard keys, so as to better transmit the magnetic field force to the keys and drive the key action.

2.3 Housing

• Material selection: The housing of keyboard testing device Solenoidmainly protects the internal coil and iron core, and can also play a certain electromagnetic shielding role. Metal materials such as stainless steel or carbon steelare usually used.  Carbon steel housing has higher strength and corrosion resistance, and can adapt to different test environments.
• Structural design: The structural design of the shell should take into account the convenience of installation and heat dissipation. There are usually mounting holes or slots to facilitate the fixing of the electromagnet to the corresponding position of the keyboard tester. At the same time, the shell may be designed with heat dissipation fins or ventilation holes to facilitate the heat generated by the coil during operation to dissipate and prevent damage to the electromagnet due to overheating.

Part 3 : The operation of the keyboard testing device solenoid is mainly based on the principle of electromagnetic induction.

3.1.Basic electromagnetic principle

When current passes through the solenoid coil of the solenoid, according to Ampere's law (also called the right-hand screw law), a magnetic field will be generated around the electromagnet. If the solenoid coil is wound around the iron core, since the iron core is a soft magnetic material with high magnetic permeability, the magnetic field lines will be concentrated inside and around the iron core, causing the iron core to be magnetized. At this time, the iron core is like a strong magnet, generating a strong magnetic field.

3.2. For example, taking a simple tubular solenoid as an example, when the current flows into one end of the solenoid coil, according to the right-hand screw rule, hold the coil with four fingers pointing in the direction of the current, and the direction pointed by the thumb is the north pole of the magnetic field. The strength of the magnetic field is related to the current size and the number of coil turns. The relationship can be described by the Biot-Savart law. To a certain extent, the larger the current and the more turns, the greater the magnetic field strength.

3.3Driving process of keyboard keys

3.3.1. In keyboard testing device, when the keyboard testing device solenoid is energized, a magnetic field is generated, which will attract the metal parts of the keyboard keys (such as the shaft of the key or metal shrapnel, etc.). For mechanical keyboards, the key shaft usually contains metal parts, and the magnetic field generated by the electromagnet will attract the shaft to move downward, thereby simulating the action of the key being pressed.

3.3.2. Taking the common blue axis mechanical keyboard as an example, the magnetic field force generated by the electromagnet acts on the metal part of the blue axis, overcoming the elastic force and friction of the axis, causing the axis to move downward, triggering the circuit inside the keyboard, and generating a signal of key pressing. When the electromagnet is powered off, the magnetic field disappears, and the key axis returns to its original position under the action of its own elastic force (such as the elastic force of the spring), simulating the action of releasing the key.

3.3.3 Signal control and test process

1. The control system in the keyboard tester controls the power-on and power-off time of the electromagnet to simulate different key operation modes, such as short press, long press, etc. By detecting whether the keyboard can correctly generate electrical signals (through the keyboard's circuit and interface) under these simulated key operations, the function of the keyboard keys can be tested.

 What exactly is the AS 4574 Tubular Linear Solenoid?

Essentially, it's an electromagnetic actuator. Its job is to transform electrical energy into linear mechanical motion. The solenoid's tubular design is key; it allows for effective magnetic flux distribution. This translates to a robust force output, smooth operation, and a long lifespan, making it well-suited for industrial use.

When the coil is powered, a magnetic field is created within the solenoid. This field then moves the plunger in a straight line, allowing for precise push or pull movements. The AS 4574 model is a common choice in automated systems, especially when dependability, a compact footprint, and consistent performance are paramount.

 Long-stroke push-pull solenoid: Beyond imagination, it is a step towards the future and precision.

Among the modern automated equipment and precision control systems, there exists a humble-looking but quite important component: the long stroke push-pull solenoid valve. Compared to the eye-catching robot joints or the sensors under highly critical scrutiny, it quietly pushes countless devices into precise operation. Let's dive into the mysteries of this wonderful device and its applications today.

What is a long-stroke push-pull solenoid valve?

A long-stroke push-pull solenoid valve is a type of electromagnetic actuator that converts electrical energy into linear mechanical motion. Compared with other kinds of solenoid valves, its main characteristic is a longer stroke, normally several millimeters to tens of millimeters. Precise bidirectional push-pull motion can be realized through the control of switching and the direction of the current. Operating principle: When the coil is turned on, the magnetic field developed by it interacts with the permanent magnet placed inside or a piece of soft magnetic material; therefore, the armature-plunger makes linear motion on its axis. When the supply is removed, due to the spring force or reverse current, the plunger resets to its initial position.