A glass cutting table uses around 150 to 400 l/min of compressed air at about 6 bar, as a rough guide: a few tens of litres for the cutting wheel and breaking, far more if the air cushion is fed from the network. A table on its own will run on a 7.5 kW 4-in-1 screw compressor such as the K 75 (1.1 m³/min at 8 bar); a table in a workshop that also edges and washes calls for a K 110 (1.7 m³/min).
The other stations in glass processing are covered on our page on the compressor for glass processing and glazing.
What is air used for on a cutting table?
A modern cutting table uses air in three ways:
- The cutting head. A cylinder presses the cutting wheel onto the glass at a pressure set according to the thickness. Consumption is low, but the pressure must be stable: if it varies, the quality of the score varies too.
- Breaking. Breaking bars or cylinders snap the glass along the score. Each break is a short but sharp burst.
- The air cushion. The table top is drilled with small holes through which air comes out; the glass floats and moves without effort or scratching. On many tables, this cushion is produced by a fan built into the table. On others, it is fed with compressed air, and it is then the biggest consumer.
So the first question to ask is: where does your table's air cushion come from? The manual says. If it comes from a fan, the compressor only sees the head and the breaking. If it comes from the network, count it as a continuous consumption for as long as the table top is blowing.
How much air do you need?
Indicative values, at about 6 bar, to be checked in the table's manual:
| Function | Consumption of around | Type |
|---|---|---|
| Cutting head and wheel oiling | 20 to 50 l/min | continuous while cutting |
| Breaking (bars, cylinders) | 50 to 150 l/min on average | in bursts |
| Air cushion fed from the network | 100 to 250 l/min | continuous while blowing |
| Station blow gun | 150 to 250 l/min | in bursts |
Depending on the equipment, a complete table therefore sits between 150 and 400 l/min. Our configurator uses 250 l/min by default.
The step-by-step calculation
Case 1: a cutting table on its own with a blow gun. Air cushion fed from the network.
- Cutting head: 40 l/min.
- Breaking: 100 l/min.
- Air cushion: 150 l/min.
- Blow gun counted at 50%: 75 l/min.
Base total: 365 l/min. With the 25% safety margin: 456 l/min. With the 20% expansion margin: 548 l/min, or about 0.55 m³/min.
The K 75 gives 1,100 l/min at 8 bar: it covers the table with plenty in reserve for a future edging machine.
Case 2: the same table in a workshop with two edging machines and a washing machine. Add 300 l/min for the edgers and 100 l/min for the washer: 765 l/min base, 956 l/min with the safety margin, 1,148 l/min with the expansion margin. That is beyond the K 75: the K 110, with 1,700 l/min at 8 bar, is the right choice.
Why does the receiver matter as much as the flow?
Breaking is a burst: for a fraction of a second, the cylinders draw far more than the average flow. If the receiver is small and far from the table, the pressure drops just when the cutting head needs it, and the next cut is less even.
Two rules:
- Volume. Our configurator recommends about one litre of receiver for every 3 l/min of demand. For 550 l/min, that makes about 180 L; for 1,150 l/min, about 380 L. The K 75's 420 L receiver easily covers the first case. For the K 110 (340 L receiver), an extra air receiver at the foot of the table is useful. The air receiver size calculator refines the result.
- Location. A small buffer receiver right next to the table is worth more than a large volume at the other end of the building. It supplies the peak without the pipe having to carry it.
What pressure should you set?
The table generally needs around 6 bar at its inlet; the head has its own regulator to set the cutting force. Set the compressor between 7 and 8 bar. If the cutting pressure varies from one sheet to the next, first check the table's filter and regulator, then the pipe diameter with the pressure drop calculator.
What air quality for the cushion and breaking?
Cushion air comes out of hundreds of holes just beneath the glass. Whatever it carries settles on the underside of the sheet:
- Water. It leaves marks and, in winter, can block holes in the table top. A refrigerated dryer is essential; it is built into the K series.
- Oil. Our compressors are oil-lubricated: the outlet filtration captures carried-over oil. Fine filtration at the table inlet completes the protection, especially if the sheets then go on to assembly or silvering.
- Particles. Rust and scale from an old network block the holes in the table top and scratch the glass. A particle filter at the foot of the table stops them.
Our guide to pressure dew point explains why air that is "dry" at the compressor outlet can turn damp again in a cold pipe.
Traps specific to the cutting table
- Counting the air cushion twice. If it comes from a built-in fan, do not add it to the compressor's flow.
- Ignoring leaks on the table. Worn valve seals and hoses leak air continuously, even with the table stopped. The leak cost calculator puts a figure on them.
- Forgetting the drains. An automatic condensate drain on the main receiver and on the buffer receiver.
The S and K series are variable speed: between two sheets, the compressor slows down instead of running idle. To choose yours, enter your table and your other machines in the configurator, or send us the table's manual with a quote request.
For your trade: Compressor for glass processing, glaziers and double glazing.