Compressed Air for 3D Printing and Additive Manufacturing

Metal powder bed fusion equipment gas consumption is mainly argon and nitrogen. Titanium alloy Ti-6Al-4V printing must use argon protection, oxygen content controlled below 100ppm, otherwise TiO₂ inclusions from melt pool oxidation will seriously damage material fatigue performance. 316L stainless steel isn't as sensitive to oxygen, nitrogen protection is enough, costs quite a bit less.

100ppm

Oxygen Limit Ti

-40°C

Powder Dew Point

600L/min

Sandblast Flow

0.01μm

Binder Filtration

Compressed air's role on metal printers is marginal. Chamber door cylinders, powder hopper switching, recoater blade reset, these pneumatic elements total air consumption is very limited. EOS M290 installation manual requirement for compressed air is 0.6 MPa, dew point +3°C, filtration precision 40μm, standard industrial level configuration, refrigerated dryer plus ordinary filter achieves it.

Metal Printing

Powder Bed Fusion

Powder

Conveying Systems

Powder conveying systems have much higher air quality requirements. Pneumatic conveying lines may be dozens of meters long, moisture and oil contamination in between will affect entire batch of powder flowability. Titanium powder getting damp clumps in the hopper, spreads with grooves when recoating, printed parts will have surface defects.

SLM Solutions' PSV powder supply system requires conveying gas source dew point -40°C, residual oil 0.01 mg/m³, this level needs adsorption dryer with multi-stage filtration to achieve.

Binder jetting process dependence on compressed air depends on printhead type. Thermal and piezoelectric heads use internal mechanism to drive droplets, don't need external gas source. Pneumatic atomizing heads mix compressed air with binder to form atomized jet, sensitive to supply air quality. ExOne S-Max installation documentation requires 0.6 MPa, dew point -20°C, filtered to 0.01μm, similar to electronics factory clean air requirements.

FDM printers have simplest compressed air needs. Industrial equipment marked interface parameters are typically 0.5-0.7 MPa, flow of tens of liters per minute, for local cooling control during high-temp material printing. Desktop machines' built-in small fans are enough for regular materials, don't need external gas source at all.

Post-processing stage compressed air consumption is often underestimated.

Post-Processing

Depowdering and Finishing Operations

Metal print depowdering is a time-consuming laborious process. Surface adhered powder handled with blow gun is still simple, powder inside internal channels and lattice structures is the trouble. Aerospace parts often have complex internal cavity designs, cooling channels twist and turn, powder stuck deep inside simply won't blow out. Sometimes parts go on vibration table to vibrate and blow simultaneously, sometimes fluidized bed treatment. Orthopedic implants with porous structure even harder to clean, pore size small, quantity large, one hip joint prosthesis depowdering might take several hours.

Depowdering process compressed air consumption depends on part complexity and batch size. Simple parts done in minutes, complex parts might need continuous blowing for tens of minutes or longer. Blow gun pressure typically 0.4-0.6 MPa, flow isn't large but duration is long, accumulated air volume is quite considerable.

Solukon automatic depowdering equipment has had increasing market presence these past few years. Part goes in sealed chamber, program controls rotation angle and vibration frequency, pulsed airflow coordinated with negative pressure recovery system clears powder out. In 2018 this equipment won TCT Awards in the post-processing category. Automated processing benefits are good consistency, high powder recovery rate, clean operating environment, downside is equipment investment isn't small.

Sandblasting is almost standard in metal additive manufacturing post-processing. Printed parts original surface roughness Ra is around 10-20μm, after sandblasting can drop to Ra 3-6μm. Surface quality improved before subsequent machining or coating can proceed.

Sandblasting process is the big consumer of compressed air in the entire additive manufacturing line. A medium sandblasting cabinet during continuous operation consumes up to 600 L/min or even higher, several cabinets running at once, compressed air system load is bigger than all the printing equipment combined.

Sandblasting pressure selected based on material and media, glass bead blasting pressure lower for gentler effect, aluminum oxide pressure higher for better removal efficiency. Titanium alloy parts use ceramic or stainless steel shot, avoid iron media contaminating the surface.

Planning additive manufacturing shop compressed air systems, post-processing area needs often account for more than half of the entire line. Production ramp-up phase post-processing equipment utilization rises, if compressed air system didn't leave enough margin, supply pressure drop problems will appear.

Air quality tiered configuration is a reasonable approach. Use points directly involved in forming process get high standards, like powder conveying system dew point -40°C, residual oil 0.01 mg/m³. Ordinary pneumatic elements use standard industrial compressed air. Post-processing equipment has higher tolerance for oil and water. Tiered configuration premise is network layout can separate different grade use points, if physical separation can't be done, can only configure uniformly to highest requirement.

Main Network

Refrigerated Drying

High Quality

Adsorption Upgrade

Terminal

Point-of-Use Filter

Main network uses refrigerated dryer to push dew point to atmospheric +3°C or so, meets most pneumatic element needs. High quality use points add adsorption dryer modules and precision filters at the end for local upgrade. Whole system on adsorption drying would have much higher energy consumption, regeneration process also consumes some compressed air, not economical.

Single equipment or small scale production can use standalone small compressor. Oil-free scroll or small screw machine with refrigerated dryer and receiver, place next to equipment, connect and ready to use, don't need to coordinate with plant utilities department. When production scale goes up, connecting to centralized supply makes more sense. Metal printing equipment single build might run for several days, air supply interruption causes build defects, possibly whole batch scrapped. Receiver capacity and network pressure stability need serious consideration, especially peak load when post-processing equipment all running at once.

Equipment inlet filter-regulator assembly is standard practice. Rust scale particles in piping and occasional contamination can damage equipment pneumatic components, terminal filtration is the last line of defense. This stuff costs a few hundred dollars, relative to millions in equipment investment it's nothing.

Piping material affects downstream air cleanliness. Old plant buildings with galvanized pipe used for over a decade, inner wall badly corroded, debris carried by airflow to equipment end blocks filters. New shops use aluminum alloy quick-connect piping, clean, light, fast to install, long-term peace of mind. Equipment final connection section uses nylon or polyurethane tubing, convenient for position adjustment.

Equipment manufacturers check compressed air parameters during installation acceptance. Supply air quality, power stability, ambient temperature and humidity all within inspection scope. Acceptance report ties to warranty terms, specs written in technical documents that should be met, meet them.