Technical Principles of Metal Filled Filament
Metal Filled Filament is a composite filament made by mixing metal powder with a polymer binder. The metal powder content is typically 80–90% (by volume), with the remainder consisting of wax, polymers, and other binding components. After FDM printing, the part undergoes debinding (removal of the binder) and sintering (melting and densification of the metal powder), ultimately producing a near fully dense metal part.
This technological route is commonly referred to as Metal FDM or Bound Metal Deposition (BMD), and is a low-cost alternative to traditional metal 3D printing technologies such as SLM and EBM.
Types and Characteristics of Metal Filled Filament
Copper-Based Filament
| Parameter | Typical Value |
|---|---|
| Metal content | 85–90% volume fraction |
| Printing temperature | 200–230°C |
| Heated bed temperature | 50–60°C |
| Density after sintering | 95–98% of theoretical density |
| Electrical conductivity | 70–85% of pure copper after sintering |
| Appearance | Red copper or bronze color |
Copper-based filament is suitable for conductive parts, heat exchangers, decorative items, artworks, and other applications. Printing is relatively easy, and the sintering temperature is relatively low (about 900–1000°C).
Stainless Steel-Based Filament
| Parameter | Typical Value |
|---|---|
| Metal content | 85–90% volume fraction |
| Printing temperature | 200–240°C |
| Heated bed temperature | 50–70°C |
| Density after sintering | 96–99% of theoretical density |
| Mechanical strength | Comparable to forged stainless steel after sintering |
| Appearance | Silver-gray, can be polished to a mirror finish |
Stainless steel-based filament is suitable for high-strength structural parts, functional parts, tooling fixtures, and more. The sintering temperature is relatively high (about 1300–1400°C), requiring a professional sintering furnace.
Other Metal Systems
- Titanium alloy filament: aerospace and medical applications, sintering temperature above 1500°C
- Tool steel filament: mold manufacturing, can be hardened by heat treatment after sintering
- Precious metal filament: gold and silver jewelry, small-batch custom production
Key Points of the FDM Printing Process
Equipment Requirements
Metal filled filament places the following requirements on the printer:
- Extrusion system: hardened steel or ruby nozzle (metal powder causes severe wear on brass nozzles)
- Extruder mechanism: direct drive is recommended, as the filament is brittle and prone to breaking
- Hot end temperature: a standard printer is sufficient (200–240°C)
Printing Parameters
| Parameter | Recommended Value | Notes |
|---|---|---|
| Nozzle temperature | 200–230°C | Adjust according to the filament instructions |
| Heated bed temperature | 50–60°C | Helps first-layer adhesion |
| Print speed | 20–40 mm/s | Low speed ensures stable extrusion |
| Layer height | 0.1–0.2 mm | A thinner layer height helps achieve more uniform sintering |
| Infill | 100% | Solid printing; hollow structures will collapse during sintering |
| Wall thickness | ≥2 mm | Too thin and it will deform easily after sintering |
Special Notes
- Nozzle wear: metal powder will wear brass nozzles; hardened steel nozzles (marked HS) or ruby nozzles are recommended
- Filament brittleness: metal
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