For 10 pneumatic screwdriving stations on an assembly line, you generally need between 0.6 and 1.3 m³/min at 6 bar at the tool, depending on the type of screwdriver and the cycle rate. A K 75 (1.1 m³/min at 8 bar) covers most lines. For pulse tools or a high cycle rate, step up to the K 110 (1.7 m³/min at 8 bar).
Why you do not add up all 10 screwdrivers
A screwdriver only uses air while it is driving a screw, a few seconds per screw. In between, the operator picks up the part, positions it and takes a screw. The tool is idle.
Adding the 10 rated consumptions would give a compressor far too large. Work with the duty cycle instead: the share of time the screwdriver is actually running. On a manual assembly station it is often between 20 and 40%. Time a cycle on your own line to find yours.
Our page on compressors for electronics assembly gives the overview of the whole workshop. Here we size the screwdriving line on its own.
Step by step calculation
Consumption figures are indicative. The exact value is in each screwdriver's manual, often in L/min at 6.3 bar.
Base case: 10 straight shut-off screwdrivers.
- Running consumption: 200 L/min per tool (common range: 150 to 300 L/min).
- Duty cycle: 25%, about 15 seconds of screwdriving per minute.
- Average consumption: 10 × 200 × 0.25 = 500 L/min.
- 25% margin for leaks and peaks: 500 × 1.25 = 625 L/min, or 0.63 m³/min.
The K 75 delivers 1.1 m³/min at 8 bar: it covers this need and leaves a reserve for two blow guns or future stations.
Three versions of the line
| Case | Calculation | Need with margin | Recommended model |
|---|---|---|---|
| 10 straight screwdrivers, 25% | 10 × 200 × 0.25 × 1.25 | 625 L/min | K 75 |
| 10 pulse screwdrivers, 25% | 10 × 300 × 0.25 × 1.25 | 938 L/min | K 75, close to its limit |
| 10 screwdrivers, high rate, 40% | 10 × 250 × 0.40 × 1.25 | 1,250 L/min | K 110 |
With pulse tools, the K 75 runs close to its maximum. If more stations are added, the K 110 is more comfortable.
Does your workshop already have a receiver, a dryer and filters? The S 75 delivers the same flow as the K 75 (1.1 m³/min at 8 bar), without the built-in receiver and dryer.
Pressure at the station sets the torque
This is the main pitfall with pneumatic screwdriving. A screwdriver's torque depends on the pressure it receives. If the pressure drops when several stations drive at once, screws end up under-tightened.
- Set the compressor to 8 bar and fit a pressure regulator at each station, set to the value in the manual. The tool then always gets the same pressure, even when the network fluctuates.
- Get the pipework right. A pipe that is too small or too long drops the pressure as soon as air flows. Our guide on connecting a compressor to the air network gives the sizing rules.
- Plan for a receiver. It absorbs peaks when several stations start together. The K 75 and K 110 have a built-in 420 L and 340 L receiver. For a network you are completing, the air receiver size calculator gives the volume.
Our article on how to calculate compressor pressure explains the link between working pressure, pressure drop and setting.
Air quality and maintenance
- Water wears air motors and rusts the inside of screwdrivers. A refrigerated dryer, built into the K Series, solves this.
- Lubrication. Follow each screwdriver's manual: some need a lubricator at the station, others do not. On a line that assembles circuit boards, keep any oil mist away from the products.
- A point of use filter protects the tool from particles in the network.
- Compressor maintenance. First service at 500 hours, then every 1,500 hours. The controller shows the reminder.
Send us the list of your screwdrivers with their consumption and your cycle time in a quote request: we will check the calculation and the model with you.
For your trade: Compressor for electronics manufacturing and assembly.