Material development
Developing the materials for our magnet solutions means that we can influence the result from the beginning – and be responsible for it. The permanent dialogue between the material production and the production departments guarantees the quality and reliable implementation of all functional requirements. This material expertise is unique in Europe: Apart from MS-Schramberg, there is no other magnet manufacturer in Europe who will produce such a wide range of magnetic materials while also taking care of the subsequent production and machining.
State-of-the-art analysis and measurement processes in our in-house laboratory guarantee the reliable quality of the materials we develop and produce. You can count on it completely!
Our process competence begins in the production of powders and compounds. We are therefore able to optimally tailor the materials to the downstream processing steps, which is essential for guaranteeing an efficient, high-quality production process.
We use the following materials in our powder development and production:
- Rare-earth elements (REE)
- Neodymium iron boron (NdFeB)
- Samarium cobalt (SmCo)
- Hard ferrite (HF)
We use the following materials in our compound development and production:
- Thermoplastic (PPS/PA6 and PA12 matrix)
- NdFeB/HF (isotropic/anisotropic)
- Elastomer (NBR, HNBR)/HF (anisotropic)
- Thermosetting plastic (epoxy resin)/NdFeB (isotropic)
Pressing technology
The production process of sintered hard ferrite magnets is similar to that of the production of technical ceramics.
First, a so-called "green body" is manufactured from a magnetic powder that corresponds to the respective magnet quality via a pressing process. The magnet is created during the subsequent sintering in continuous furnaces.
In many cases, the sintered magnets receive their final shape through a mechanical machining process involving diamond tools and various grinding processes. The magnets are magnetized at the end of the process chain or after they have been shipped to the customer.
The pressing processes can generally be distinguished between "wet pressing" and "dry pressing".
We use the following materials in our magnet and system solutions:
- Hard ferrite (isotropic/anisotropic)
- Rare-earth elements (anisotropic)
- NdFeB pw (isotropic)
- Plastic-bonded pressing
During the production of sintered magnets, magnetic powder is pressed into so-called "green bodies" and then sintered. In the case of magnets with an axially preferred direction, the magnetic powder must already be magnetically aligned during the pressing process. This is done via a coil system integrated into the tool. If the pressing direction and the magnetic alignment field match, the process is referred to as axial pressing.
During the production of NdFeB and SmCo magnets, the so-called isostatic pressing process is used in addition to the axial and transverse field pressing processes.
The magnetic powder is filled into flexible molds, magnetically aligned and grouted evenly from all sides in an oil bath. This process allows the production of high remanent magnets because the magnetically aligned powder particles are evenly condensed from all sides. This prevents a mechanical discharging of the powder particles during the pressing process.
Sintering technology
The sintering process is carried out in combined vacuum-inert gas sintering furnaces. The sinter profile is dependent on the material composition and the required magnetic properties.
The sintering process may last for up to 24 hours. The volume shrinkage that occurs during the sintering process is comparable with that of the hard ferrite magnets. As a result of the different textures produced during the forming process, the shrinkage of the blank in the preferred magnetic direction and vertically toward the preferred direction varies. This complicates the production of delicate structures.
- Hard ferrite continuous furnace
- Rare earth vacuum chamber furnace
Mechanical processing
During the production of our magnet and system solutions, specific processing methods are often required. Our mechanical processing work is comprised of the following procedures:
- Cylindrical grinding (external/internal cylindrical grinding)
- Surface grinding/flat grinding
- Form grinding
- Separation
- Vibratory finishing
- Eroding
Injection molding technology
Injection molding is used primarily in the processing of plastics. When using this shaping process, plastics (or other materials) are first plasticized in an injection unit and then injected into a mold with high pressure. When it cools in the mold, the liquid plastic becomes solid and, following a defined cooling off period, it can be ejected from the mold. When using this process, parts can be used in most cases without requiring post-treatment. Depending on the abrasiveness of the plastic, tremendous quantities of up to millions of parts can be produced with a single cavity.
By overmolding insert parts with a magnetic compound, magnets can be combined with axes, bushes or other functional elements.
We have automated the process of supplying and overmolding insert parts, such as sintered or plastic-bonded magnets, axes, bushes, etc. If needed, the finished part can be qualified via integrated 100% testing.
The multi-component injection molding technique allows the combination of multiple materials in one injection molding process even if they have different material properties.
Compared to conventional processes, the use of the multi-component injection molding technique offers distinct advantages:
- Great accuracy, since all components are injected in the same mold within a single production step without join part or individual part tolerances
- Different material properties can be combined in one component
- No expensive handling needed
- Inexpensive production of high quantities of complicated assemblies
We have used the multi-component injection molding technique for years for the production of high-quality magnets.
The multi-station technique is used for assemblies with insert parts. In a station not actively integrated in the injection molding process, the completed assembly can be removed and a new insert part can be loaded. Because of the parallel operation of these processes to the actual injection molding process, cycle time savings of up to 30 per cent can be achieved depending on the complexity of the molded and insert parts.
Multi-stage injection molding is among the addition methods that are part of injection molding and it is used for thick-walled molded parts or plastic-bonded magnets. The molded part of the magnet is produced in two separate, subsequent process steps. In each process step, approximately half of the component volume is injected. Due to the roughly squared dependency of the cooling period to the wall thickness, the resulting cooling period is reduced drastically. As the same time, the component quality increases due to the reduced individual shrinkage of the partial components.
Joining technology
A magnet assembly is a "product" that becomes a customer-specific "magnetic system" as a result of the further processing of sintered or plastic-bonded permanent magnets. We combine magnets with other technical components, which, for example, makes a subsequent assembly much easier.
Sintered and plastic-bonded magnets can best be combined with other technical components by gluing. Without a frictional connection and across a wide temperature range. In the area of industrial series production, we have wide-ranging experience that spans many years. Employees specially trained in gluing technology guarantee expert processing and therefore high-quality magnetic systems. Our state-of-the-art plants are available for the efficient and high-quality production of magnet assemblies.
We process the following adhesives for the production of magnet assemblies:
- Epoxies and polyurethane (1- and 2-component)
- Cyanoacrylates and methyl methacrylates
- Anaerobic adhesives
- Radiation curable adhesives
Other joining technologies that are part of gluing technology are better for certain magnet assemblies, for example:
- Pressing on or press fitting components
- Heat shrinking
- Clinching
- Clipping in
- Laser welding
- Ultrasonic welding
- Casting and caulking
For your magnet assembly, you will always benefit from the in-depth knowledge we have acquired in a wide range of projects.
Corresponding to your specific magnetic system requirements, you can count on an optimal product and processing recommendation.
