As a rough guide, an air drill uses around 300 to 450 l/min at 6.3 bar while it is running, a rivet gun around 100 to 200 l/min, and a pneumatic-hydraulic blind rivet tool around 1 to 2 litres per rivet. Because these tools work in bursts, they count at half in the calculation: six drilling and riveting stations will generally run on a compressor delivering 1.1 to 1.7 m³/min.
How much air does an air drill use?
The drill is the hungriest tool in structural assembly. Its consumption depends on its power and speed far more than on the hole diameter. A small straight drill for pilot holes uses less than a powerful angle drill for reaming.
- Light straight drill: around 250 to 350 l/min.
- Angle drill or more powerful drill: around 350 to 450 l/min.
- Positive feed drill on a jig: its consumption is in the manual, often higher, and it runs for longer on each cycle.
The drill does not run all the time. The technician positions the jig, drills, deburrs and moves on to the next hole. Over an hour's work, the drill runs for only a small part of the time. That is why it counts at half: the air receiver supplies the peaks and the compressor refills the receiver between holes.
How much air does a rivet gun use?
There are two families of tools to tell apart:
- The rivet gun (pneumatic riveting hammer) drives a solid rivet while a second operator holds the bucking bar. It uses around 100 to 200 l/min depending on its size, in bursts of a few seconds.
- The pneumatic-hydraulic blind rivet tool pulls the rivet mandrel. It only uses air on each setting cycle, around 1 to 2 litres of free air per rivet. At 10 rivets a minute, that comes to around 10 to 20 l/min: almost nothing.
The exact consumption is in each tool's manual, often given in CFM or in litres per cycle. Our flow and pressure converter converts CFM into l/min.
How do you add up the tools on an assembly line?
Take an assembly cell at a subcontractor: four technicians on two jigs, with a total of four drills, four rivet guns, two blind rivet tools and two blow guns between them. They cannot use everything at once: at most four tools are running together.
- Rank the tools from hungriest to least hungry, each counted at half since they all work in bursts: drill 400 / 2 = 200 l/min, rivet gun 150 / 2 = 75 l/min, blow gun 150 / 2 = 75 l/min, blind rivet tool negligible.
- Keep the four hungriest, one per technician: four drills, so 4 × 200 = 800 l/min. That is the worst case, when everyone is drilling at the same time.
- 25% safety margin for leaks and wear: 800 × 1.25 = 1,000 l/min.
- 20% expansion margin for a fifth station: 1,000 × 1.2 = 1,200 l/min, or 1.2 m³/min.
The K 110, at 1.7 m³/min at 8 bar, covers this cell with spare capacity for a sander. This is the method our configurator uses: only the tools genuinely used at the same time count, the hungriest first.
How many stations per compressor?
| Compressor | Flow at 8 bar | Simultaneous drills (calculation above) |
|---|---|---|
| K 75, 4-in-1 7.5 kW | 1.1 m³/min | about 3 |
| K 110, 4-in-1 11 kW | 1.7 m³/min | about 5 |
| K 150, 4-in-1 15 kW | 2.2 m³/min | about 7 |
| S 220 PM, screw 22 kW | 3.6 m³/min | about 12 |
Each drill here counts as 200 l/min, with 50% combined margins, so 300 l/min. If sanders or spray guns run on the same network, count them in full and take off the equivalent number of drills. These figures are indicative: do the calculation with your own tool manuals.
What pressure for drilling and riveting?
The tools are designed for 6.3 bar at the inlet. It is the pressure at the tool that counts, not at the compressor. A drill receiving 5 bar instead of 6.3 loses noticeably in power and speed: drilling drags and the hole finish suffers. For a rivet gun, pressure determines the impact: it is set at the regulator to suit the rivet, as stated in the work instructions.
Set the compressor at around 7 to 8 bar and look after the network: drops and hoses of adequate diameter, high-flow quick couplings. Check the pressure at the inlet of the furthest tool, with the tool running. Our pressure drop tool checks the pipe diameter.
Common mistakes with assembly tooling
- Adding up the maximum consumption of every tool. Ten tools at 300 l/min do not make 3 m³/min if there are only four technicians. An oversized compressor costs more to buy and runs badly.
- Forgetting the blow guns. Blowing away swarf after drilling is common. A blow gun left open continuously uses as much air as a drill.
- Neglecting tool lubrication. Drills and rivet guns need lubricating according to their manual, with an in-line lubricator or a few drops of oil. Keep that lubricator on the assembly stations, never on the line feeding painting or surface preparation.
- Letting water reach the tools. It washes out the lubricant and rusts the mechanisms. A 4-in-1 compressor with a dryer solves the problem at source. See water in compressed air.
For the whole workshop, see our page on the compressor for aerospace, and our article on pneumatic screwdrivers if your line uses them. Send us your tool list with a quote request and we will check the calculation with you.
For your trade: Compressor for aerospace, aircraft maintenance and subcontracting.