Sm1Co5 and Sm2Co17 identify two samarium cobalt material families, not two complete purchase specifications. Choosing a custom SmCo magnet requires a proposed grade, part geometry, magnetization and operating conditions. Use this comparison to prepare that specification.
Understanding SmCo Magnet Grades
A family name does not establish the delivered magnetic output, resistance to demagnetization or usable temperature. Grade names and published values can differ between suppliers. Request the applicable data sheet and agree whether quoted properties are typical values or acceptance limits.
Sm1Co5 vs Sm2Co17: Selection Comparison
| Selection factor | Sm1Co5 (1:5) | Sm2Co17 (2:17) |
|---|---|---|
| Material family | SmCo 1:5 family; confirm the specific supplier grade. | SmCo 2:17 family; confirm the specific supplier grade. |
| Magnetic output | Compare the specified Br and (BH)max values. | Often considered for higher energy product; verify the actual grade values. |
| Intrinsic coercivity (Hcj) | Check the proposed grade and temperature; 1:5 is not automatically lower. | Check the proposed grade and temperature; 2:17 is not automatically higher. |
| Operating temperature | Use the grade data and demagnetization curve at the intended working point. | Use the grade data and demagnetization curve; special high-temperature material requires separate qualification. |
| Custom part quotation | Specify dimensions, tolerances, magnetization, environment, quantity and inspection. | Specify the same requirements so quotes can be compared on an equivalent basis. |
Material Family and Manufacturing
The 1:5 and 2:17 labels describe different alloy families. Commercial 2:17 formulations include additional alloying elements; exact percentages should come from the proposed material specification. Do not use a nominal chemical ratio as a finished-part performance guarantee.
Both families require care during fabrication and assembly because SmCo is hard and brittle. Specify thin sections, holes, edge condition and handling requirements on the drawing. Magnetizing equipment and fixtures must also suit the material and pole pattern; confirm feasibility before fixing the design.
Magnetic Properties to Compare
- Br and (BH)max: Compare data for the proposed grades, then check the required field or flux in the actual geometry. A larger energy product does not by itself establish the field at a sensor or across a working gap.
- Hcj: Do not rank all 1:5 material below all 2:17 material. Arnold’s published SmCo grade table shows different coercivity values within its range. Those are third-party material data, not Magnetstek delivery specifications.
- Temperature: Evaluate the demagnetization curve and working point at temperature, thermal cycling and allowed irreversible loss. Curie temperature is not an allowable continuous operating temperature. See the SmCo temperature selection guide.
Application and Assembly Checks
For motors, couplings or sensors, start with the required magnetic function and installation conditions. State the air gap, nearby steel, opposing magnetic fields, mounting method and exposure to heat or chemicals. Neither material-family label establishes qualification for a particular aerospace, automotive or medical system.
Agree how the finished part will be checked: dimensions, magnetization direction or pole pattern, field or flux measurement position, and any thermal or environmental test. Include the fixture and acceptance criteria when a measured magnetic result is required.
Cost Considerations
Compare quotations against the same drawing and acceptance requirements. Grade, geometry, tolerances, machining, magnetization, coating, quantity and inspection can affect cost. The family name alone does not establish which finished part will be cheaper.
Prepare an SmCo Grade RFQ
Send the drawing revision, proposed grade or required magnetic output, magnetization direction, temperature range and duty cycle, environment, quantity and inspection criteria. If the material is undecided, ask for a grade proposal with its applicable data sheet and operating assumptions. Use the SmCo grade selection inquiry to share these requirements.
Technical references: Adams SmCo family and fabrication overview; Arnold high-temperature SmCo technical paper. These explain material selection principles and do not establish Magnetstek supply capability.
Related: Custom SmCo Magnets, Sm1Co5 Magnets, Sm2Co17 Magnets
