In the additive production of metal parts, the process conditions have a direct influence on the quality of the finished product. Gas management in particular plays a key role in 3D metal printing. Gas flow control and moisture content monitoring in the printer chamber can be ensured using air velocity and dew point sensors.
Most 3D printing processes use a protective gas – such as argon, nitrogen or helium - to create an inert atmosphere in the 3D printer. This avoids undesirable chemical reactions (e.g., oxidation) or contamination of the metal powder in the process chamber.
Conventional 3D Metal Printing Methods:
The most popular 3D metal printing method is the powder sintering process. An energy source sinters or melts a metal powder, the finished component part is built up layer by layer. Direct Metal Laser Sintering (DMLS) or Electron Beam Manufacturing (EBM) are based on this principle.
In Laser Metal Deposition welding (LMD), a laser generates a melt bead; the metal powder is applied by a nozzle.
In Binder Jetting Technology, a binder is applied in layers to a metal powder bed and cured. The component part is then sintered in an oven.
Uniform gas distribution, and low humidity in the process chamber, are decisive for high-quality component parts from the 3D printer. Thanks to air velocity and dew point sensors, these parameters can be monitored reliably and precisely.
A stable inert gas atmosphere is essential for high-quality 3D metal printing products. If the gas supply and gas removal do not function correctly, this can result in the following issues:
- The powder coat applied is too thin or too thick
- The powder is eddied or eroded
- Sparks/contamination can settle on the workpiece
- Insufficient protection of the work area against O2 and H2; oxidation occurs
All of these points impact on the quality of the 3D printed component part.
An air velocity sensor – positioned on the 3D printer's gas inlet channel – detects even the slightest gas flow. The gas supply can be precisely controlled to achieve the best possible conditions in the printing chamber. On top of this, efficient gas management reduces the inert gas consumption and ensures safe and cost-efficient operations.
Benefits of E+E air velocity sensors:
- Excellent measuring accuracy and long-term stability
- Applicable for a wide air velocity and temperature range
- Rugged metal housing for harsh environments
In addition to the gas flow, moisture also plays a central role in the printing process.
- Damp metal powder can clump
- Condensation in the printer chamber can impair the component properties
- Dew formation on the lenses leads to refraction and structural defects
Depending on the size of the process chamber, the use of 2 to 3 dew point sensors is recommended for monitoring the moisture content in the material and gas.
Benefits of E+E dew point sensors:
- Precise dew point measurement at low temperatures (measuring range down to -60 °Td)
- Easy integration thanks to analogue output or Modbus RTU interface
- Compact design, rugged stainless steel housing