For an aluminium and PVC window manufacturing workshop of 5 to 10 people, the air demand usually lies between 1 and 2 m³/min at 7 or 8 bar, margins included. With 5 people on a simple PVC line, a K 75 (1.1 m³/min at 8 bar) is enough; with 8 people on mixed aluminium and PVC fabrication, you need a K 110 (1.7 m³/min); with 10 people or two shifts, a K 150 (2.2 m³/min). These three models are variable speed 4-in-1 screw compressors, with a built-in air receiver, refrigerated dryer and filtration.
The uses of air machine by machine are described on our page on the compressor for PVC and aluminium window fabrication. Here, we carry out the full sizing, in five steps.
Step 1 - which machines should you list?
Walk round the workshop and note each pneumatic machine, with its consumption and minimum pressure taken from the manual. If the manual gives litres per cycle, convert to l/min: litres per cycle × cycles per hour ÷ 60. Without a manual, here are orders of magnitude, as a rough guide:
| Machine | Indicative consumption | How it is counted |
|---|---|---|
| Corner cleaner | 250 l/min | continuous, at 100% |
| Double mitre saw | 150 l/min | continuous, at 100% |
| Profile machining centre | 150 l/min | continuous, at 100% |
| 4-head PVC welder | 150 l/min | in cycles, at 50% |
| 2-head PVC welder | 80 l/min | in cycles, at 50% |
| Aluminium corner crimper | 80 l/min | intermittent, at 50% |
| Copy router / punch press | 50 l/min | intermittent, at 50% |
| Screwdriver | 200 l/min | intermittent, at 50% |
| Blow gun | 150 l/min | intermittent, at 50% |
Why count some stations at half? Because they use air in short bursts, and the air receiver supplies those bursts. This is the rule in our configurator. Details on screwdrivers are in our article on the compressor for pneumatic screwdrivers.
Step 2 - how many stations run at the same time?
A window fabrication shop almost always has more machines than operators. Eight people do not run twelve stations at once: one is glazing, another fitting hardware, a third moving frames around. So you add up the hungriest stations, as many as there are people on production at the same time. That is the difference between a correctly sized compressor and an oversized one that spends its day ticking over.
Step 3 - the calculation for three typical workshops
Case 1, simple PVC line, 5 people. Double mitre saw, 2-head welder, corner cleaner, two screwdrivers, one blow gun.
- The five hungriest stations: corner cleaner 250 + saw 150 + two screwdrivers 2 × 100 + blow gun 75 = 675 l/min (the 2-head welder, counted at 40 l/min, comes sixth).
- 25% safety margin: 675 × 1.25 = 844 l/min.
- 20% expansion margin: 844 × 1.2 = 1,013 l/min, or about 1 m³/min.
- Model: K 75, 1.1 m³/min at 8 bar, 420 L receiver.
Case 2, mixed aluminium and PVC fabrication, 8 people. Two double mitre saws, 4-head welder, corner cleaner, profile machining centre, crimper, punch press, three screwdrivers, two blow guns.
- The eight hungriest stations: corner cleaner 250 + two saws 2 × 150 + machining centre 150 + three screwdrivers 3 × 100 + one blow gun 75 = 1,075 l/min.
- 25% safety margin: 1,075 × 1.25 = 1,344 l/min.
- 20% expansion margin: 1,344 × 1.2 = 1,613 l/min, or about 1.6 m³/min.
- Model: K 110, 1.7 m³/min at 8 bar. The reserve is small: if a second corner cleaner is planned, go straight to the K 150.
Case 3, two lines, 10 people. Case 2 plus a second corner cleaner and a second 4-head welder.
- The ten hungriest stations: two corner cleaners 2 × 250 + two saws 2 × 150 + machining centre 150 + three screwdrivers 3 × 100 + two blow guns 2 × 75 = 1,400 l/min.
- With both margins: 1,400 × 1.25 × 1.2 = 2,100 l/min, or 2.1 m³/min.
- Model: K 150, 2.2 m³/min at 8 bar.
To compare with a manual expressed in m³/min or m³/h: divide l/min by 1,000 to get m³/min, then multiply by 60 for m³/h. The 1,613 l/min of case 2 thus make 1.6 m³/min, or about 97 m³/h (around 57 CFM).
Step 4 - what pressure, what air receiver, what dryer?
Pressure. Take the highest minimum pressure from your manuals, often around 6 bar, and add about 1 bar for losses: a setting of 7 to 8 bar is suitable. For pressure-sensitive machines, such as the crimper and the welder, fit a regulator with a pressure gauge at the inlet.
Air receiver. The built-in receivers (420 L on the K 75, 340 L on the K 110 and K 150) absorb the peaks of a standard line. If several welders and corner cleaners start their cycles together, or if the line is long, an extra receiver at the far end of the network steadies the pressure. The air receiver size calculator gives the volume, and our range of air receivers completes the setup.
Dryer. A refrigerated dryer and outlet filtration are essential for the cylinders, the machining centre's minimum quantity lubrication and blowing off the profiles. The 4-in-1 models include them. Our compressors are lubricated: the outlet filtration holds back the carried-over oil, and a fine filter at the machining centre completes the protection.
Step 5 - one compressor or two?
When losing air stops the whole line, a single compressor is a risk. From 8 to 10 people, or on two shifts, two compressors taking turns are often better than a single larger one: for example two K 110 units instead of one 22 kW compressor. Each covers most of the production when the other is being serviced or breaks down. For larger production, the S 220 PM delivers 3.6 m³/min at 8 bar. Our technicians work out with you how to share the load between the two machines.
During a replacement project or a peak in orders, compressor hire with screw units from 5.5 to 132 kW keeps production going.
The pitfalls for a workshop of 5 to 10 people
- Sizing on the sum of the manuals. You end up with a compressor twice too big. Count the stations that genuinely run at the same time.
- Forgetting growth. A second line or a second machining centre often arrives two or three years after the purchase. The 20% margin is there for that.
- Neglecting the pipework. A pipe that is too narrow starves the end of the line of pressure. The pressure drop calculator checks the diameters.
- Ignoring leaks. In an existing workshop, have them measured before choosing a bigger compressor. A compressed air audit measures the real consumption.
For your workshop, run the calculation with the configurator or send us the list of your machines and the number of people with a quote request.
For your trade: Compressor for PVC and aluminium window fabrication.