What Are Sew In Magnets?
Sew in magnets are magnetic closures designed to be sewn directly into fabrics and other flexible materials. They are commonly used in garments, bags, curtains, covers, and other textile products.
Unlike exposed magnetic fasteners, sew in magnets can be concealed between layers of fabric, leaving no visible magnetic hardware on the finished product.
Most sew in magnets consist of Neodymium (NdFeB) magnets encapsulated between PVC, TPU, EVA, or similar heat-sealable plastic films. The films are sealed around the magnets to form a protective envelope.
A wider flexible border is left around the magnetic core so that the component can be stitched into the surrounding material without sewing through or directly contacting the magnets.
Also known as sewing magnets or sewable magnets, these products combine rigid magnetic cores with flexible outer envelopes that can be integrated into textile products during sewing. Their external form is simple, but the internal construction can vary depending on the required closure force, mating structure, product thickness, and manufacturing requirements.
Why Sew In Magnets Are Often Treated as Commodity Products?
Within the magnet industry, sew in magnets are often regarded as commodity products and can even serve as shorthand for the lower end of the permanent magnet market. This reputation reflects both the markets they serve and the way these products are typically manufactured.
Sew in magnets are consumed in large quantities by garment, bag, home textile, packaging, and other light industrial manufacturers. Individual components have relatively low value, designs are often standardized, and purchasing decisions can be highly sensitive to small differences in unit price.
At sufficiently high volumes, even small savings in magnetic material, steel parts, plastic film, or assembly cost become commercially significant.
The same cost pressure also affects product specifications. Magnet coatings, dimensional tolerances, magnetic consistency, encapsulation finish, and other quality requirements are often defined around the needs of high-volume production rather than those of precision magnetic assemblies. The surrounding PVC, TPU, or EVA envelope also provides additional protection, allowing some surface and cosmetic requirements to be relaxed.
For this reason, the industry’s low-end perception of sew in magnets is not entirely unfounded. The problem arises when that perception is extended to every design choice used in these products. Cost optimization can involve less demanding specifications, but it can also come from using magnetic material more efficiently. The distinction becomes especially important in single sided sew in magnets.
How Sew In Magnets Are Constructed?
Although sew in magnets appear simple from the outside, their construction is closer to a small encapsulated magnetic component than to a bare magnet. The magnetic core is positioned between two layers of PVC, TPU, EVA, or another heat-sealable plastic film, which are then sealed around it to form a closed envelope.
The sealed area immediately around the magnet helps keep the magnetic core in position, while the wider outer margin remains flexible enough for stitching. This sewing flange also keeps needles and thread away from the rigid magnet itself. Its width and overall envelope shape can be adjusted to suit different textile constructions and sewing processes.
The magnetic core is usually made from Neodymium magnets, but the internal arrangement is not always identical. Some designs contain only a conventional disc magnet or block magnet, while others combine the magnet with steel components to control where the magnetic flux is concentrated. The external envelope may therefore look almost the same even when the magnetic behavior and material usage inside are quite different.
Encapsulation also changes what is required from the magnet surface. Because the magnetic core is normally isolated from direct handling and much of the surrounding environment, its coating is primarily selected to provide adequate protection during manufacturing and service rather than to deliver a highly finished exposed surface.
Single Sided Sew In Magnets: Cost Reduction or Better Material Utilization?
Single sided sew in magnets are closely associated with cost reduction.
Instead of relying on a larger magnet alone, these designs combine a Neodymium magnet with a steel backing piece or shell. The steel provides a lower-reluctance path for the magnetic flux and directs more of the useful field toward the working face.
This arrangement does not make the magnet truly single-pole, nor does it eliminate the magnetic field on the opposite side. “Single sided” simply describes the intended magnetic behavior of the assembly: one face is designed to provide most of the useful attraction, while the reverse side contributes much less to the closure.
In high-volume textile products, this can reduce the amount of magnetic material required to achieve a specified holding performance on the working side. Since steel is much less expensive than Neodymium magnetic material, replacing part of the magnetic volume with an appropriately designed steel component can lower the total assembly cost without proportionally reducing useful magnetic performance.
Single Sided Magnetic Circuit
Because this construction is so common in price-sensitive products, single sided magnets have acquired a somewhat negative reputation within the magnet industry. However, the design principle itself is not inherently low-end. It is fundamentally a simple magnetic circuit design: the steel component provides a preferred return path for magnetic flux and helps concentrate more of the useful field on the working side. Where only one working face is required, this can improve the utilization of magnetic material rather than simply reduce it. The important question is not whether less magnetic material has been used, but whether the finished assembly delivers the required magnetic performance under its actual operating conditions.
Magnetic Force in Real Textile Assemblies
The magnetic force of sew in magnets cannot be judged from the bare magnet alone. Once the magnets are enclosed in plastic film and sewn into a finished product, the fabric layers, encapsulation thickness, alignment, and mating structure all become part of the magnetic gap.
Even a small increase in separation can noticeably reduce attraction. Thick fabrics, folded seams, padding, or multiple material layers can therefore make the closure feel much weaker than the same magnets in direct contact. Misalignment can have a similar effect, especially when relatively small magnets are used.
The mating structure also matters. Sew in magnets may be paired magnet to magnet or used against a steel counterpart, and single sided designs must be installed with the intended working face toward the mating component. Reversing the assembly, changing the steel thickness, or using a smaller mating area can significantly change the available holding force.
For this reason, magnet size or nominal pull force should not be treated as the final closure performance of the textile product. Selection is better based on the complete assembly, including the expected material thickness, mating arrangement, required opening force, and normal manufacturing tolerances.
Custom Options for Sew In Magnets
Sew in magnets are usually adapted to the finished textile product rather than selected only by magnet diameter or nominal pull force. Customization can include the magnet size and grade, PVC, TPU, or EVA envelope dimensions, film thickness, sewing border width, and the overall shape of the encapsulated component.
The internal construction can also be adjusted. Conventional magnet-to-magnet designs, single sided structures with steel backing, and magnet-to-steel arrangements may be used depending on the required closure force and cost target. Polarity and working-face orientation should be defined before production, particularly when multiple magnets are sewn into the same product or when the components must align in a specific direction.
For volume projects, these variables are best considered together. Increasing magnet size is only one way to change closure performance; envelope thickness, fabric spacing, steel geometry, and the mating arrangement can be equally important to the final result.
Other Flexible Magnetic Products
Sew in magnets are only one way of integrating magnetic functions into flexible products. Where a project requires continuous magnetic attraction, greater freedom in shape, or a magnetic element that can follow a curved path, other flexible magnetic materials may be more suitable than individually encapsulated magnets.
Our flexible magnetic products include flexible magnet cords and other custom flexible magnetic components that can be supplied in different dimensions and constructions for integration into textile, sealing, positioning, and attachment systems. These products provide a different balance of flexibility, magnetic force, and ease of integration compared with sew in magnets.
Choosing between discrete sew in magnets and continuous flexible magnetic products ultimately depends on how the magnetic function needs to be distributed throughout the finished product.
