Rotary Magnetic Scale Nonius
For rotary or linear motion control applications, magnetic encoder systems offer a simple, precise, and cost-effective solution. Operating on a non-contact magnetic sensing principle, they excel at continuous or incremental positioning, motion control, and various other scenarios requiring reliable angular or linear feedback.
The key advantage lies in the co-designed and optimized pairing of the encoder IC with the magnetic scale. Our magnetic scales provide flexible mounting options and can be tailored to your mechanical design, allowing for seamless integration onto flange faces, shaft outer diameters, or inside bores.
We support your needs from prototype development through to large-scale production. Our goal is to ensure you receive not just an isolated component, but a complete, high-accuracy measurement solution.
Magnetic Scale Material
1. Rubber Magnet (Flexible Ferrite)
Primary Composition:
Magnetic Material: Ferrite powder (e.g., Strontium or Barium Ferrite).
Rubber Elastomer: Typically NBR (Nitrile Butadiene Rubber).
Core Process:
Compounding & Mixing: Similar to standard rubber compounding. The magnetic powder, raw rubber, and additives are uniformly mixed on a mill and then calendered into sheets or rolls of the desired thickness.
Curing & Shaping: The material is vulcanized (cured under heat and pressure), causing the polymer matrix to cross-link and solidify around the magnetic particles.
Key Characteristics & Your Applications: This is the most widely used material for magnetic rings. It offers excellent flexibility, easy processing, and a good balance of performance and cost-effectiveness, although its magnetic strength is relatively low.
2. Injection-Molded Magnet
Primary Composition:
Magnetic Material: Strontium or Barium Ferrite powder. For applications requiring higher magnetic performance, Neodymium Iron Boron (NdFeB) powder may be used.
Thermoplastic Polymer: Typically Nylon (e.g., PA66) or PPS (Polyphenylene Sulfide).
Core Process:
Compounding: The magnetic powder, polymer resin, and processing aids are compounded to create uniform injection-molding pellets.
Injection Molding: These pellets are melted and injected under high pressure into a mold cavity to form the final part shape.
Key Characteristics & Your Applications: The process allows for the creation of complex, net-shape parts with high dimensional accuracy and good mechanical strength in a single step.
3. Sintered Ferrite
Primary Composition:
Magnetic Material: High-purity Strontium or Barium Ferrite powder, with tightly controlled particle size distribution.
Core Process:
Powder Prep & Pressing: The raw powder is compacted into a “green” body of the desired shape using a die in a dry or wet pressing process.
Sintering: This is the critical step. The green part is fired in a furnace at 1200°C – 1300°C for an extended period. This causes solid-state diffusion and densification, transforming it into a hard, ceramic magnet.
Grinding / Finishing: The sintered part often requires grinding (e.g., surface or OD grinding) to achieve final dimensional tolerances.
Key Characteristics & Your Applications: You get a hard, brittle (ceramic-like) magnet with excellent corrosion resistance and thermal stability. It offers medium magnetic performance at a very low cost.
4. Bonded Neodymium (NdFeB) Magnet
Primary Composition:
Magnetic Material: Rapidly solidified (MQU-G type) NdFeB powder.
Binder: A thermosetting resin, most commonly epoxy.
Core Process:
Mixing & Molding: The magnetic powder is uniformly mixed with the binder. The mixture is then placed in a mold and cured under heat, which triggers a chemical reaction in the resin to solidify the part.
Surface Treatment & Magnetization: The bonded magnet is typically coated (e.g., with Ni-Cu-Ni or Zn plating) for corrosion protection, and then magnetized.
Key Characteristics & Your Applications: This material provides the highest magnetic performance among polymer-bonded options and allows for complex multi-pole magnetization. However, its temperature resistance and mechanical strength are lower than its sintered NdFeB counterpart, and it is more expensive than ferrites. The parts are rigid and can be brittle, making very thin cross-sections challenging to produce.
Standard Magnetic Scales
BOGEN, IC-Haus, and many other magnetic encoder manufacturers (such as RENISHAW, POSIC, etc.) commonly adopt 1.28mm and 1.5mm as standard nominal pole pitches.
- 1.28mm is a classic value with direct lineage to the grating pitch widely used in early optical encoder disks. This allows magnetic-electric replacement solutions to achieve compatibility without altering the fundamental design of subsequent electronic processing units, such as interpolators.
- 1.5mm, on the other hand, is a more regular dimension that is easier for calculation and manufacturing. It is particularly suitable for larger magnetic rings where an extremely high pole count is not the primary requirement. It provides an excellent fundamental physical period for high-precision signal interpolation.
| Type | Magnet OD | Magnet ID | Master Track Ø | Nonius Track Ø | Magnet Material | Pole Pitch |
|---|---|---|---|---|---|---|
| Axial | 15.50 mm | 3.00 mm | 13.04 mm | 5.84 mm | E | 1.28 mm |
| Axial | 29.00 mm | 15.10 mm | 26.08 mm | 18.88 mm | E | 1.28 mm |
| Axial | 30.00 mm | 11.50 mm | 26.08 mm | 18.88 mm | F | 1.28 mm |
| Axial | 34.00 mm | 20.40 mm | 30.56 mm | 23.36 mm | F | 1.50 mm |
| Axial | 33.50 mm | 20.00 mm | 30.35 mm | 23.15 mm | E | 1.50 mm |
| Axial | 55.00 mm | 42.00 mm | 52.15 mm | 44.95 mm | F | 1.28 mm |
| Axial | 55.00 mm | 42.00 mm | 51.78 mm | 45.28 mm | E | 1.28 mm |
| Axial | 64.50 mm | 51.00 mm | 61.12 mm | 53.92 mm | F | 1.50 mm |
| Axial | 64.00 mm | 51.00 mm | 61.12 mm | 53.92 mm | E | 1.50 mm |
| Radial | 24.50 mm | 17.00 mm | — | — | F | 1.28 mm |
| Radial | 50.55 mm | 38.00 mm | — | — | F | 1.28 mm |
| Radial | 50.55 mm | 48.55 mm | — | — | E | 1.28 mm |
| Radial | 59.50 mm | 43.50 mm | — | — | F | 1.50 mm |
| Radial | 59.60 mm | 57.60 mm | — | — | E | 1.50 mm |
Parameter Key:
Magnet Material:
E= Elastomer (Rubber Magnet),F= Hard Ferrite (Sintered Ferrite).Type: Axial rings are for face detection and feature dual tracks (Master/Nonius). Radial rings are for shaft/sleeve detection and do not have track diameter parameters.
Pole Pitch: This is the core magnetic performance parameter and must match the specification of the compatible ASIC.
Rubber Magnetic Parameters
| 1 | Remanence (Br) @20°C | 200 mT | |
| 2 | Coercivity (Hc) | 240 KA/m | |
| 3 | Temperature Coefficient of Remanence (αBr) | -0,19 %/K | |
1. Remanence (Br)：A higher Br means a stronger magnetic “field” and a greater pulling force. It’s the core indicator of the magnet’s strength.
2. Coercivity (Hc)：Coercivity measures the magnet’s ability to withstand external demagnetizing fields (like from other magnets, heat, or physical shock) without losing its magnetism.
3. Temperature Coefficient of Remanence (αBr)：This coefficient (usually a negative percentage) tells you how much the magnet’s strength (Br) changes with temperature.
Mechanical Structure Of Elastomer Magnetic Scale
Our standard magnetic rings are primarily composed of bonded rubber magnets and metal brackets, a design that offers the following advantages:
1) ultra-thin profiles, down to 1mm, can be achieved;
2) greater design flexibility, enabling easy adaptation to various product dimensions;
3) improved resilience due to the rubber magnet material, which provides good resistance to vibration, shock, and thermal cycling.
Rubber Magnetic Material
The primary manufacturing step for rubber magnetic material involves the use of a rubber mixer to uniformly blend magnetic powder (such as ferrite powder), pre‑vulcanization rubber, and various additives in specific proportions.
This is a critical stage, as it must ensure complete encapsulation of the powder by the rubber to form a homogeneous composite compound. This uniformity directly impacts the magnetic field consistency and pole accuracy of the material after the subsequent magnetization process.
Rubber magnets also have certain limitations, primarily in terms of magnetic properties such as flux density, which are lower compared to rare-earth magnets or molded plastic magnetic materials.
If you have specific requirements in these parameters, we can also provide composite material solutions beyond rubber magnets to better meet your application needs.
Product Inspection
The production process and pre-shipment inspection of precision magnetic rings are indispensable steps. Our magnetic rings are utilized in applications requiring high-accuracy position and angle measurement, where product dimensions and magnetic parameters directly impact our customers’ performance and output precision.
Our quality control include, but are not limited to, the following:
✅ Dimensional sampling inspection
✅ 100% magnetic parameter test
Let’s discuss your specific requirements—pole number, dimension, mechanical integration, magnetic properties.We can also select the suitable magnetic materials for encoder rings to your specific application requirements, offering a balance between performance and cost-effectiveness.We’ll work with you to deliver a precision magnetic sensing solution:
- Standard magnetic ring
- Custom design magnetic ring
FAQ
1.What is the standard MOQ for your Magnetic Scale?
We are flexible to discuss volume-based adjustments for prototype or trial orders.
2.Can you produce custom desgin samples before full production? Is there a charge?
Yes, we can provide custom designsamples for validation. Samples are typically charged at a nominal fee to cover material and setup costs. Lead time for sample building is generally 4 weeks after design confirmation.
3.What is the typical lead time for standard Magnetic Scale orders?
For standard products with no stock, the lead time is 2 weeks after order confirmation and receipt of deposit.
4.Can I request custom Magnetic Scale specifications?
Yes,we fully support customization for parameters such as inner/outer diameter, mounting hole positions, thickness, and magnetic properties to meet specific application needs.