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Powder flammability and combustion of selected Formlabs SLS powders
Powder flammability and combustion of selected Formlabs SLS powders
The properties of combustible dusts are discussed in A Practical Guide to 5 Important Properties of Combustible Dusts:
- MEC (Minimum Explosible Concentration) is the minimum amount of dust suspended in air that supports an explosion and is usually measured in g/m3.
- MIE (Minimum Ignition Energy) is the minimum amount of energy required to cause flame propagation when released at a point in a dust cloud.
- MIT (Minimum Ignition Temperature) is the minimum temperature required to ignite dust and comes in two types:
- MIT for a dust cloud: the air temperature required to ignite a dust cloud.
- MIT for a dust layer: the temperature of a surface that will cause dust to ignite.
Additional information is available in the OSHA Technical Manual - Section IV, Chapter 6, Combustible Dusts. For more information about safety with Formlabs SLS products, see our support article on the topic.
Below is a table detailing the combustible properties of selected Formlabs SLS powders.
| Material | Minimum Explosive Concentration (MEC) (g/m3) | Minimum Ignition Energy (MIE) (mJ) | Minimum Autoignition Temperature (MIT) (°C) | Maximum Explosion Pressure (Pmax) (bar-g) | Deflagration Index (Kst) (bar*m/s) |
|---|---|---|---|---|---|
| Nylon 12 Powder | 40 | 650 | 430 > MIT < 805 | 6.9 | 70 |
| Nylon 11 Powder | 80 | 1000 < MIE | 460 < MIT < 1000 | 4.2 | 88 |
| Nylon 12 GF Powder | 80 | 300 < MIE < 1000 | 440 | 6.0 | 80 |
| Nylon 11 CF Powder | 80 | 300 <MIE < 1000 | 480 | 6.3 | 99 |
| Polypropylene Powder | 80 | 100 < MIE <300 | 400 | 5.8 | 71 |
| TPU 90A Powder | 100 | 300 < MIE < 1000 | 440 | 7.2 | 110 |
Particle size distribution
Particle size is analyzed using low-angle laser light scattering (LALLS). Particle size distribution is often represented by a mass fraction with key percentile indicators known as D10, D50, and D90.
- D10: Particles that make up 10% of the total weight of the sample are smaller than this diameter.
- D50: Particles that make up 50% of the total weight of the sample are smaller than this diameter.
- D90: Particles that make up 90% of the total weight of the sample are smaller than this diameter.
Particle size distribution data for selected Formlabs SLS powders:
| Material | D10 (µm) | D50 (µm) | D90 (µm) |
|---|---|---|---|
| Nylon 12 Powder | 37 | 58 | 86 |
| Nylon 11 Powder | 19 | 43 | 75 |
| Nylon 12 GF Powder | 40 | 60 | 90 |
| Nylon 11 CF Powder | 11 | 40 | 78 |
| Polypropylene Powder | 35 | 55 | 75 |
