Soft magnetic composites (SMC) are materials composed of ferromagnetic particles insulated from each other by a thin dielectric layer. The particles are bonded together using a thermoplastic or thermosetting binder, then injection molded into complex net-shape components.
Key Advantages:
High-purity iron powder with insulation coating
Insulated powder mixed with polymer binder
Net-shape forming of magnetic core
Heat treatment to optimize magnetic properties
Optional machining and quality inspection
| Property | SMC (Injection Molding) | Laminated Silicon Steel | Solid Soft Ferrite |
|---|---|---|---|
| Saturation (Bs) | 1.4-1.5 T | 1.5-2.0 T | 0.4-0.5 T |
| Permeability | 100-500 | 1000-10000 | 1000-5000 |
| Frequency Range | DC to 1 MHz | DC to 1 kHz | 1 kHz to 10 MHz |
| Eddy Current Loss | Very Low | Low (at low freq) | Very Low |
| 3D Flux Path | Yes | No (2D only) | Limited |
| Shape Complexity | Very High | Low | Medium |
| Typical Applications | High-freq inductors, motors | Power transformers, AC motors | RF transformers, filters |
| Composition | Fe + Polymer Binder |
| Saturation (Bs) | 1.4-1.5 T |
| Permeability (μmax) | 100-500 |
| Coercivity (Hc) | 100-300 A/m |
| Resistivity | 1000-10000 μΩ·cm |
| High-freq inductors | 10-500 kHz |
| EMI filters | Switching power supplies |
| DC-DC converters | Automotive electronics |
| Motor cores | BLDC, stepper motors |
| Composition | Fe-6.5%Si + Binder |
| Saturation (Bs) | 1.2-1.3 T |
| Permeability (μmax) | 200-800 |
| Core Loss | Very low at high freq |
| Advantage | No magnetostriction |
| Low-noise transformers | Audio equipment |
| High-freq power | UPS, inverters |
| EV charging | Onboard chargers |
| Medical devices | Low EMI requirements |
| Composition | Fe-50%Ni + Binder |
| Saturation (Bs) | 1.3-1.4 T |
| Permeability (μmax) | 1000-5000 |
| Advantage | High permeability |
| Cost | Higher than Fe-based |
| Current transformers | Power metering |
| Magnetic sensors | Position sensing |
| Filter inductors | Signal conditioning |
| Precision circuits | Medical, aerospace |
MIM (Metal Injection Molding) technology enables complex geometries that are difficult or impossible to achieve with traditional manufacturing methods. Below is a comprehensive design guideline.
| Feature | Capability | Note |
|---|---|---|
| Min Wall Thickness | 0.3-0.5 mm | Excellent flowability of feedstock |
| Min Hole Diameter | Ø0.3-0.5 mm | Using core pins |
| Undercuts | Supported | Using movable cores |
| Internal Cavities | Supported | Using core pins |
| Threads | Supported | Designed in mold tooling |
| Gear Profiles | Supported | Small module gears can be formed directly |
| Draft Angle | 0.5-1 degrees | Minimal draft required |
| Tolerance | ±0.02-0.08 mm | IT5-IT6 grade precision |
| Surface Roughness | Ra 0.8-1.6 um | Smooth sintered surface |
| Variable Wall | Supported | Mold tooling design |
| Feature | Status | Alternative |
|---|---|---|
| Lattice Structure | Not Suitable | Open porous structures not recommended |
| Overly Thick Sections | Caution | May cause internal defects |
| Large Flat Surfaces | Caution | May warp during sintering |
| Feature | Status | Requirements |
|---|---|---|
| Metal Inserts | Possible | Insert molding process available |
| Very Large Parts | Case-by-case | Consult with engineering team |
| High Aspect Ratio | Possible | Special tooling required |
Design Tip: MIM is ideal for small, complex parts typically weighing 0.01-250 grams. For larger parts, consider traditional PM or machining methods.
MIM parts have excellent surface condition due to the sintering process. The density of MIM parts (>7.0 g/cm3) affects surface treatment options.
Note: Density requirement (>7.0 g/cm3) is important for electroplating applications
| Treatment Type | Compatibility | Rating | Notes |
|---|---|---|---|
| Passivation | Excellent | Standard for stainless steel MIM parts | |
| Electroplating | Good | Pore sealing treatment required | |
| ED Coating | Excellent | Electrodeposition coating excellent adhesion | |
| PVD Coating | Excellent | TiN, CrN, DLC coatings available | |
| Spray Painting | Excellent | Good paint adhesion on sintered surface | |
| Polishing | Excellent | Can achieve Ra 0.1um mirror finish | |
| Mirror Polish | Excellent | High polish achievable | |
| Blackening | Excellent | Black oxide treatment available |
MIM parts typically achieve 95-98% of theoretical density (>7.0 g/cm3 for iron-based materials). Higher density provides better surface sealing and improved electroplating quality. For critical plating applications, specify high-density MIM process.
MIM offers excellent cost efficiency for medium to high volume production. Below is a general cost reference for MIM parts.
RMB per set
RMB per piece
pieces minimum
Includes tooling and first article
After sample approval
Key Insight: MIM sample/production cost ratio is typically 40-400x, meaning it is most cost-effective for high-volume production. The cost advantage of MIM becomes significant at volumes above 10,000 pieces.
Iron-based, Fe-Si, and Fe-Ni alloy compositions. We help select the optimal material for your frequency, flux density, and cost requirements.
3D FEA magnetic simulation. We optimize your core geometry for minimum losses and maximum performance.
Tight tolerance injection molding with tolerances to ±0.02mm. Complex geometries with integrated features.
ISO 9001 certified. Full magnetic testing including B-H curves, core loss measurement, and dimensional inspection.
Automated production lines for millions of parts annually. Consistent quality from first part to millionth.
Magnetic core plus winding assembly. We can provide complete magnetic components ready for your production line.
SMC materials can operate effectively from DC to over 1 MHz. The optimal frequency depends on the specific material grade and particle size. Typical applications range from 10 kHz to 500 kHz.
SMC offers higher saturation flux density (1.4-1.5T vs 0.4-0.5T for ferrite) but lower permeability. For high current applications requiring high flux density at high frequencies, SMC is often the better choice.
Yes, SMC is increasingly used in high-speed motors and generators, especially those operating above 10 kHz electrical frequency. The 3D magnetic isotropy allows for novel motor designs with improved performance.
Tooling: 4-6 weeks for custom molds. Samples: 2-3 weeks after tooling approval. Production: 3-4 weeks. Standard catalog parts ship in 7-15 days.
Yes, we provide complete magnetic characterization including B-H curves, permeability plots, and core loss data at various frequencies and flux densities. Custom test conditions available on request.
PPS-bonded SMC materials can operate up to 200°C. For standard applications, the continuous operating temperature is typically 120-150°C depending on the specific material grade.
Contact our soft magnetic material specialists for custom quotes, material selection guidance, or magnetic design support. We help you optimize your magnetic circuit for performance and cost.
Contact: Cindy | Phone: +86 021 5512 8901 | Email: sales1@brm-metal.com
