Why Custom Electromagnets Are Necessary — Standard Products Alone Cannot Produce a Magnetic Field Optimized for the Equipment’s Purpose and Installation Environment
An electromagnet is a device that generates the required magnetic field by applying electric current to a coil. The magnetic field strength can be adjusted according to the current conditions, while the direction and distribution of the magnetic field can be controlled through the design of the iron core and pole structure. These characteristics allow electromagnets to be used in a wide range of applications requiring precise magnetic field control, including particle accelerators, medical equipment, semiconductor equipment, materials research, and automated systems.
However, the same electromagnet cannot be applied to every type of equipment. Each system has different requirements for magnetic field strength and uniformity, effective field region, installation space, operating time, power supply, and cooling conditions. In particular, when magnetic field quality directly affects equipment performance or experimental results, simply achieving the target magnetic flux density is not sufficient.
To stably generate a magnetic field of the required strength and shape at the required location, the pole geometry, coil, iron core, cooling structure, power conditions, and installation environment must be reviewed as an integrated system. This is why custom electromagnets are required instead of standard products.
Magnetic Field Quality in the Actual Working Region Matters More Than the Tesla Rating
When evaluating an electromagnet, the first specification commonly reviewed is its maximum magnetic flux density. However, even electromagnets that generate the same magnetic field strength may perform differently when installed in actual equipment.
What matters is not simply how many Tesla the electromagnet can generate. It is also necessary to confirm whether the required magnetic field strength is achieved within the effective region where the specimen or particle beam is located, how uniform the field distribution is, and whether the field remains stable during long-term operation. Other important performance criteria include whether the same magnetic field is reproduced when current is repeatedly applied and the extent of stray magnetic fields that may affect surrounding equipment.
For example, equipment used to analyze the magnetic properties of materials must generate a uniform magnetic field throughout the entire region occupied by the specimen. By contrast, systems that deflect or focus particle beams must generate magnetic field gradients and multipole components suited to their intended function, rather than simply producing a constant uniform field.
Electromagnets must therefore be designed not merely according to maximum output, but according to the shape and quality of the magnetic field required at the intended location.
Each System Requires Different Conditions, from Uniform Fields to Deflection and Gradient Fields
Electromagnets must generate different forms of magnetic fields depending on their intended application. In materials research and magnetic property evaluation, it is important to create a uniform magnetic field within a defined space. Systems that use electron beams or particle beams require magnetic field distributions capable of bending the beam in a specific direction or focusing it to the desired size. In medical devices and magnetically controlled robotic systems, it may also be necessary to generate time-varying magnetic fields or multidirectional magnetic fields in order to precisely control the position and direction of movement of the target.
These differences directly affect the shape and number of poles, coil arrangement, iron core structure, pole gap, and applied current conditions. Even when two electromagnets have similar external dimensions and maximum magnetic field strengths, their internal structures and detailed designs must differ if their intended applications are different.
A custom electromagnet is not a product whose external dimensions are simply modified to match the size and output requested by the customer. It is an engineered result developed by first analyzing the function the electromagnet must perform and then newly designing the magnetic field distribution and structure required to realize that function.
The Installation Environment Is the Starting Point of Electromagnet Design
Electromagnets are typically installed not as standalone devices, but as integral components of research equipment or industrial systems. Therefore, even if an electromagnet delivers excellent magnetic field performance, it cannot be practically applied if it cannot be installed within the equipment or if it interferes with surrounding components.
During the design stage, the overall allowable dimensions and the effective pole gap must first be confirmed. Sufficient space must also be provided for the specimen, chamber, vacuum tube, or beam path. In addition, the mounting method, reference surfaces for alignment with the equipment frame, space for power cables and cooling lines, accessibility for maintenance personnel, and the structural capability of the frame to support the electromagnet’s weight must all be taken into consideration.
These considerations become particularly important when adding an electromagnet to existing equipment or installing a new magnetic field system within a confined space. In such cases, standard products are often unsuitable because the overall geometry, pole structure, and coil arrangement must be adapted to the actual installation environment.
Custom design is the process of evaluating both magnetic field performance and mechanical constraints simultaneously to ensure that the electromagnet operates properly as part of the complete system.
Stable Operating Conditions Are as Important as High Magnetic Field Strength
A conventional electromagnet generates a magnetic field by passing electric current through a coil. During this process, heat is generated due to the electrical resistance of the winding. As the applied current increases or the operating duration becomes longer, the amount of generated heat also increases. Consequently, magnetic field design and thermal design cannot be treated as separate considerations.
When designing a coil, engineers must evaluate the number of turns, conductor cross-sectional area, applied current and voltage, coil resistance, and power consumption together. Acceptable current density, insulation class, operating duration, and the expected temperature rise must also be considered. An electromagnet intended for intermittent operation and one designed for continuous long-term operation may require entirely different coil structures, even if both are designed to generate the same magnetic field strength.
Increasing the current solely to achieve the target magnetic field may cause excessive coil temperatures. Conversely, increasing the conductor size or the number of turns excessively to reduce heat generation can lead to larger overall dimensions, greater weight, higher power consumption, and increased manufacturing costs.
The objective of custom coil design is to achieve the required magnetic field while maintaining stable operation within the allowable temperature limits by balancing both the electrical and thermal design requirements.
Cooling Methods Must Be Selected According to Operating Conditions
As the temperature of a conventional electromagnet increases, coil resistance and power consumption may also increase. Prolonged exposure to elevated temperatures can shorten the service life of insulation materials, while thermal expansion of the coil and iron core structure may alter the pole gap or alignment. These changes can ultimately affect magnetic field stability and repeatability.
Electromagnets operated for short periods at relatively low current levels may be adequately cooled through natural convection or air cooling. In contrast, systems that must maintain high magnetic fields during continuous operation may require water-cooled coils or dedicated cooling equipment.
The cooling method should be determined not only by the operating current but also by whether continuous operation is required, the allowable coil temperature, available installation space, cooling water flow rate and pressure, and maintenance conditions. When a water-cooling system is adopted, engineers must evaluate not only cooling performance but also flow-path pressure loss, connection integrity, leak detection, and overall safety measures.
Proper cooling design ensures not only that the electromagnet can generate the target magnetic field, but also that it can maintain its performance reliably under actual operating conditions.
How a Custom Electromagnet Is Developed
— From Pole Shape Design to Electromagnetic Analysis, Precision Manufacturing, and Magnetic Field Measurement
Pole Shape Engineering From Pole Shape Design to Manufacturing and Measurement: The Process of Achieving Magnetic Field Quality
While the coil generates the magnetic field in an electromagnet, the iron core and poles guide the resulting magnetic flux into the required region. In particular, the shape of the pole face and the gap between the poles have a significant influence on the magnetic field strength and field uniformity within the effective region.
To produce a uniform magnetic field over a wide area, the size, geometry, and end profile of the pole faces must be carefully designed. When a specific magnetic field gradient is required, the pole faces may be designed with curved or asymmetric geometries. Electromagnets used for particle beam control employ different numbers and arrangements of poles depending on their function, such as Dipole, Quadrupole, and Corrector magnets.
The cross-sectional area of the iron core and the yoke structure are also critical design factors. If the magnetic flux density in a particular region approaches the saturation limit of the core material, increasing the current may no longer produce the expected increase in magnetic field strength, and the field distribution may become nonlinear. Fringe fields generated at the pole edges must also be considered, as they influence the effective magnetic length and may affect surrounding equipment.
Once manufactured, the pole geometry is difficult to modify. Therefore, it is essential to compare multiple design alternatives through electromagnetic analysis before manufacturing and determine the structure capable of achieving the target magnetic field distribution.
Predicting Magnetic Field Distribution and Saturation Before Manufacturing
Custom electromagnets are generally designed using electromagnetic analysis and simulation. These analyses make it possible to evaluate the following characteristics before manufacturing:
- Magnetic field strength and distribution as a function of applied current
- Magnetic flux flow within the iron core
- Locations where magnetic saturation is likely to occur
- Fringe fields at the pole edges
- Stray magnetic fields in the surrounding area
Engineers can also compare the performance of different design alternatives by varying the pole width and gap, coil position and winding conditions, and iron core dimensions. This makes it possible to reduce unnecessary use of steel and copper while optimizing the overall size and power consumption without compromising the required performance.
However, simulation results alone cannot guarantee the performance of the final product. Although material properties and geometric conditions can be modeled under ideal assumptions, actual manufacturing introduces variations in core material properties, machining accuracy, assembly tolerances, and coil positioning.
For this reason, electromagnetic analysis should not be regarded as an independent process, but as part of an integrated development workflow that continues through precision manufacturing and magnetic field measurement.
Precision Manufacturing Turns the Design into Reality
A precision electromagnet is not completed by design drawings alone. To reproduce the magnetic field performance predicted through analysis, every stage of iron core machining, coil manufacturing, assembly, and alignment must be carefully controlled.
If the pole face geometry or the pole gap deviates from the design specifications, both magnetic field uniformity and the magnetic center may shift. If the left and right coils are not positioned symmetrically or if the winding quality is inconsistent, the magnetic field distribution may become asymmetric. Inadequate coil insulation or impregnation may also lead to vibration or thermal problems during operation.
For electromagnets requiring exceptionally high magnetic field quality, it is particularly important to ensure that the mechanical center coincides with the magnetic center. This requires comprehensive control of the following factors:
- Machining accuracy of the pole faces and assembly reference surfaces
- Assembly tolerances of the iron core
- Coil positioning and left-right symmetry
- Winding quality, insulation, and impregnation
- Integrity of the cooling channels
- Alignment of the mechanical center and the magnetic center
Reliable manufacturing of a custom electromagnet requires designers to understand the characteristics of the manufacturing process and to consider in advance how manufacturing tolerances may affect magnetic field performance.
Verifying Design Performance Through Magnetic Field Measurement
Completing the manufacturing of an electromagnet does not automatically guarantee that the required performance has been achieved. A verification process is required in which the actual magnetic field is measured and compared with the design specifications.
Measuring only the maximum magnetic field at the center point is not sufficient. The magnetic field characteristics must be evaluated over a range of applied currents, and the field distribution and uniformity must be measured at multiple locations throughout the actual working region.
Depending on the application, the following characteristics may be evaluated:
- Magnetic field characteristics as a function of applied current
- Magnetic field distribution and uniformity within the effective region
- Location of the magnetic center
- Repeatability during repeated operation
- Magnetic field stability during long-term operation
- Stray magnetic fields in the surrounding area
- Hysteresis characteristics during current ramp-up and ramp-down
Electromagnets with iron cores may exhibit hysteresis depending on their operating history. Therefore, it is important to evaluate how the magnetic field changes during current increase and decrease and, if necessary, establish a standardized magnetization procedure. For electromagnets used in precision experiments or beam control systems, such operating procedures can directly influence the overall system performance.
When design, manufacturing, and measurement are separated, identifying the cause of performance deviations and implementing corrective actions becomes much more difficult. By contrast, performing electromagnetic design, manufacturing, and magnetic field measurement within a unified engineering framework makes it possible to feed measurement data back into both the design and manufacturing processes.
KR TECH possesses integrated development capabilities covering electromagnetic design, magnetic analysis, precision manufacturing, coil winding, assembly, and magnetic field measurement for conventional electromagnets.
When a Custom Electromagnet Is More Suitable Than a Standard Product
Not every project requires a custom electromagnet. If the required magnetic field, installation space, and operating conditions are relatively straightforward and match the specifications of a standard product, a commercial electromagnet may offer advantages in terms of cost and delivery time.
However, custom design should be considered under the following conditions:
High magnetic field uniformity is required within a specific region.
The electromagnet must be installed in a confined space.
Mechanical integration with existing equipment is required.
Continuous long-term operation or a specialized cooling structure is necessary.
Stray magnetic fields affecting surrounding equipment must be minimized.
A specific magnetic field gradient or directional field is required.
Magnetic field measurement results and validation data are required.
Future expansion of the operating range or control conditions must be accommodated.
Although a standard product may have a lower initial purchase cost, the total system cost can ultimately become higher if additional support structures, cooling equipment, or dedicated power supplies are required for integration.
Therefore, selecting an electromagnet should involve more than simply comparing product prices. Suitability should be evaluated by considering magnetic field performance, system integration, operational stability, maintainability, and future expandability. A custom electromagnet is not merely a magnet with a unique external shape—it is the result of integrated engineering designed to generate the required magnetic field distribution at the required location with stability and repeatability.
KR TECH’s Approach to Integrated Engineering for Conventional Electromagnets
An electromagnet is one component that supplies a magnetic field within a larger system, but the quality of that magnetic field can determine the final performance of the equipment. If the field does not meet the required conditions, the reliability of experimental results may decline, the trajectory and focus of a particle beam may become unstable, and the control accuracy of magnetically actuated systems may also deteriorate.
A custom electromagnet is not simply a product with modified external dimensions. It is the result of evaluating the required magnetic field, installation environment, power supply, cooling, control, and measurement conditions as a single integrated system. This approach makes it possible to achieve the target magnetic field performance while using the available space efficiently and managing power consumption and heat generation appropriately.
Reducing magnetic interference with nearby sensors and electronic equipment, while creating a structure that is easy to install and maintain, is another important value of custom design. When future equipment expansion or changes in operating conditions are considered during the initial design stage, the time and cost required for later system modifications can also be reduced.
In fields such as particle accelerators, medical equipment, and research instruments, where magnetic field quality directly affects system outcomes, an electromagnet should be treated not as a simple purchased component, but as a core engineering element.
The development of a custom electromagnet does not end with confirming the maximum magnetic field and product dimensions requested by the customer. It is first necessary to understand the equipment in which the electromagnet will be used, the region in which it must generate the magnetic field, the required field shape, the current conditions, and the intended operating duration.
Based on these requirements, electromagnetic analysis is performed, and the poles, iron core, coils, and cooling structure are designed. The electromagnet is then completed through precision machining, coil manufacturing, and assembly, after which actual magnetic field measurements are conducted to confirm whether the design specifications have been achieved. If the measured results differ from the target values, the cause must be analyzed and the design or manufacturing conditions refined.
KR TECH has built its design, manufacturing, and measurement capabilities around conventional electromagnets operated at room temperature. Its core capability lies in designing magnetic fields suited to each customer’s purpose and environment, manufacturing the corresponding product, and verifying its performance through precision measurement.
Ultimately, the value of a custom electromagnet does not lie in producing a magnet with a unique shape. It lies in generating a magnetic field of the required strength and distribution at the required location with stability and repeatability. This is the most important reason custom electromagnets are needed in precision research and industrial systems.