Skip to Content
Contact
mail
call

Welding Robot Extraction: How to Properly Capture Welding Fumes at Robot Cells

Load from Welding Robots 

The robot itself is not at risk, but the smoke spreads without capture in the hall and affects all employees – from the operator who loads parts to the assembly next door. Which extraction system is suitable depends on the design of the robot system: compact cells are extracted and kept under negative pressure, stationary robots receive a suction hood, and mobile robots have a traveling hood. What is not captured by the system is taken over by the hall air.

Facts at a Glance

• Welding robots operate with long arc times and a consistently high deposition rate – each system often produces more welding fumes than a manual welding station.

• The obligation to record data at the point of origin also applies to automated welding: Section 43 of the Austrian Occupational Safety Act (ASchG), TRGS 528 in Germany.

• Protective fences and light barriers protect against the robot's mechanics, not against the smoke.

• Traveling extraction hoods can also be implemented for travel paths of more than 50 m.

• Critical moments are when the system opens: rotary table, door, crane loading.

Why does a welding robot need an extraction system at all?

Because the hazard does not disappear, but simply shifts. With manual welding, the welder stands directly in the plume of fumes. With robotic welding, the fumes rise unhindered, disperse beneath the workshop roof and, as the day progresses, settle back down into the work area. Those affected include plant operators, workers at neighbouring workstations and maintenance staff who have to enter the cell.

Added to this is the volume of work: a robot welds almost non-stop, usually using the MAG process, which is one of the smoke-heaviest methods. Without an extraction system, the smoke also builds up on sensors, cable guides and clamping devices – with consequences for the system’s availability and maintenance requirements.

What does the law require?

The same rules apply to robotic welding as to manual welding. In Austria, Section 43(2) of the Occupational Safety Act (ASchG) requires that hazardous airborne particles be captured as completely as possible at source, with ventilation used only as a supplementary measure. In Germany, TRGS 528 primarily requires extraction at the source; mechanical room ventilation provides supplementary protection for the remaining workers. If filtered air is recirculated into the workshop, certified equipment of welding fume extraction class W3 is required for carcinogenic substances – such as when welding chromium-nickel steel.

Which extraction system is suitable for which robot system?

The right solution arises from the design of the system: How large is the working area, does the robot move, and how do the components get in and out?


Compact Cell: Extract and Maintain Under Negative Pressure

Compact robot cells for small parts are usually enclosed; the operator places parts on a turntable while welding occurs on the other side. The enclosure alone is not sufficient: when the table is turned or the door is opened, smoke that has accumulated in the cell escapes. A continuous extraction system that maintains a slight negative pressure in the cell is effective. Hall air then flows in through all openings instead of smoke flowing out.

Stationary robot: extraction hood over the work area

If the robot is freely standing in the hall, for larger components, an extraction hood is the standard solution. It utilizes thermals: the hot smoke rises and is captured at the underside of the hood. Strip curtains encapsulate the area against cross currents and create a storage volume where smoke peaks can accumulate. The size of the hood is determined by the robot's work area; modular hoods can be extended almost indefinitely.

Robot on rail or portal: traveling extraction hood

If the robot moves between several workstations, a fixed hood over the entire distance would be unnecessarily large and energy-intensive. A traveling hood follows the robot and captures the smoke wherever welding is taking place – even over travel distances of more than 50 m. 

Highly mobile robots: large-area separation

With very agile robots and large, changing components, hoods reach their limits. In such cases, the work area is separated on a large scale with curtains; transport paths are closed with overlapping slats. The extraction system captures air from the entire separated area. The air volume is significantly higher than with a hood – making heat recovery and demand-oriented control even more important.

Fume extraction at the robot

A suction nozzle on the robotic torch captures the smoke directly at the arc, via a high vacuum system. It requires little air but increases the interference contour of the torch and raises the risk of collision at tight seams. It does not capture residual smoke after welding. It is particularly suitable for easily accessible joints and where there is no space for hoods.

Why the hall air should be planned 

No extraction system captures 100 per cent. According to Kappa’s empirical data, with a well-designed extraction hood, around 10 per cent of the fumes remain in the hall; with burner extraction systems, the figure is higher. Added to this are gases that welding fume filters do not retain, and the waste heat from the equipment. In halls with several robotic systems, this all adds up. A workshop ventilation solution with a fresh air supply close to the floor forces residual fumes and heat upwards, where they are captured and filtered. In the Kappa A.I.R.™ system, extraction at the machine and workshop ventilation are combined into a single system.

Saving energy with robot extraction

  • Connect the extraction system to the robot controller: The extraction system only operates whilst the robot is welding, with a short run-on time to allow for post-welding fumes.
  • Capture rather than dilute: the closer the hood or enclosure fits to the process, the less air needs to be moved and reheated in winter.
  • Riders instead of large canopies on mobile robots.
  • Utilising heat: Heat recovery or permitted air recirculation keep the process waste heat within the hall.

Checklist: This data is needed for planning

  • Welding processes, materials and filler metals (e.g. MAG, stainless steel, aluminium)
  • Number of robots, arc welding times and shift work
  • The robot’s working area and travel range, and the cell’s design
  • Component sizes and loading and unloading (rotary table, door, crane, forklift)
  • Hall height, crane runways and existing ventilation
  • Fire and explosion protection, for example with aluminum or sparks


Interesting facts

FAQ


Yes. Even with automated welding, health-threatening fumes and gases are generated that pollute the hall without capture. The obligation to capture at the source according to § 43 ASchG or TRGS 528 applies regardless of whether welding is done manually or with a robot.


Usually a suction hood above the work area with strip curtains. According to Kappa's experience values, it achieves up to 90% capture rate and is largely independent of the welding position. For compact cells, suction of the cell under negative pressure is the appropriate solution.

No. Without extraction, smoke accumulates in the cell and escapes when the door is opened or the table is turned. Only continuous extraction with slight negative pressure prevents this.

When the seams are easily accessible and there is no space for a hood. Disadvantages include the larger disturbance contour of the burner, the necessary high vacuum, and that after-smoking is not captured.

A hood that moves with a movable robot on a rail or portal and captures the smoke directly above the current welding point. It is also possible for travel distances of more than 50 m and keeps the other workplaces free.

Sources