Wood Products and Woodworking
Full guide to compressed air for wood shops and wood products plants.
See wood products air guide
Application: CNC routing and machining
Air Compressors for CNC Machines and Routers: Sizing Your Shop Right
- Since 1978
- Sullair dealer since 1984
- 14 locations
- under 2 hour response
CNC Machine Air Spec Plate
- Pressure
- 80 to 100 psi typical
- CFM per machine
- 10 to 25 CFM
- Holddown
- Separate vacuum pump
- Moisture
- Refrigerated dryer standard
- Dealer
- Sullair since 1984
What size air compressor and vacuum do I need for my CNC router or machining center?
A CNC router has two separate utility systems that are commonly confused: compressed air for the spindle, tool changer, and chip blow-off, and vacuum for the holddown table. Getting both sized correctly is critical because an undersized compressor causes tool change failures, and a venturi holddown running off compressed air costs several times more in energy than a dedicated vacuum pump. The guide below covers both.
CNC machining air and vacuum lineup
-
Rotary Screw (Single to Mid CNC)
- HP range
- 5 to 25 HP
- Output
- 20 to 100 CFM
- Best for
- 1 to 5 CNC machines
- Duty
- 100 percent rated
-
Larger Rotary Screw (Multi-CNC)
- HP range
- 25 to 100 HP
- Output
- 100 to 400 CFM
- Best for
- 5 or more CNC machines
- Control
- VSD for variable demand
-
Vacuum Pumps (Holddown Tables)
- Use
- Spoilboard holddown
- Types
- Rotary vane, claw, screw
- Note
- Separate from compressed air
- Control
- VSD matched to table demand
-
Refrigerated Dryers
- Use
- CNC air supply moisture
- Dew point
- 35 to 50 F pressure
- Protection
- Spindle and tool changers
- Sizing
- Matched to compressor CFM
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CNC machine air demand by function
CNC routers and machining centers use compressed air for several different functions with different demand patterns. The holddown table is a vacuum system, separate from the compressed air.
| CNC function | System | Typical demand | Pressure or vacuum level |
|---|---|---|---|
| Spindle cooling and purge | Compressed air | 2 to 5 CFM continuous | 80 to 100 psi |
| Pneumatic tool change (ATC) | Compressed air | 3 to 8 CFM per event, brief | 80 to 100 psi minimum |
| Chip blow-off | Compressed air | 5 to 15 CFM intermittent | 80 to 100 psi |
| Pneumatic edge clamps | Compressed air | 2 to 5 CFM during clamping | 80 psi |
| Holddown table | Vacuum pump (separate) | Size to table area and porosity | 10 to 25 in-Hg typical |
Combined compressed air demand per router: 10 to 25 CFM at 80 to 100 psi. Check your machine manufacturer specification plate for exact values.
For holddown vacuum sizing, contact us: table area, spoilboard porosity, and material type determine the vacuum pump CFM.
Run the numbers yourself
- CFM calculator: total the spindle, tool change, blow-off, and clamp air across your routers into one compressor size.
- Air receiver tank calculator: size storage that holds 80 to 100 psi through the brief tool change burst so collets seat reliably.
- Compressed air leak calculator: price leaks that pull pressure below the ATC minimum and cause tool change faults.
What compressed air really costs
- 10% of US industrial electricity goes to compressed air Source: US DOE Compressed Air Sourcebook
- 20 to 30% of compressed air is typically lost to leaks Source: US DOE Compressed Air Sourcebook
- 75% of ten year compressor cost is energy, not purchase price Source: CAGI life cycle cost data
- under 2 hr average emergency response across our territory Source: Brabazon dispatch
Where CNC machines use compressed air and vacuum
-
Spindle cooling and purge
Compressed air cooling the spindle bearing zone and purging chips and dust from the tool path.
-
Pneumatic tool changes
ATC systems using compressed air to actuate tool release and clamping at every tool change event.
-
Chip blow-off
Clearing chips and dust from the work surface, part, and spoilboard between passes and operations.
-
Vacuum holddown tables
Dedicated vacuum pump holding panels, sheets, and parts to the spoilboard during machining.
-
Part clamping and fixturing
Pneumatic edge clamps and fixture actuators positioning work before and during the cutting cycle.
-
Dust collection assist
Compressed air assist jets directing chip and dust flow into the dust collection system.
-
Door and panel actuation
Safety enclosure doors, chip guards, and tool magazine doors operated by compressed air cylinders.
-
Multi-spindle routing centers
Production routing centers with multiple spindles and tool carousels requiring higher simultaneous CFM.
What keeps CNC tool changers and spindles healthy
Four air quality and sizing disciplines prevent the tool change failures, spindle damage, and holddown problems that shut down CNC production.
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Compressed air and vacuum are separate systems on a CNC router
The most common sizing mistake on CNC routers is combining the compressed air demand and the holddown vacuum demand into one number. They are different technologies from different machines. The compressor supplies the spindle, tool changer, and blow-off. A vacuum pump supplies the holddown table. Size them separately and do not attempt to generate holddown vacuum from compressed air through venturi ejectors: the energy cost is prohibitive at production cycle rates.
-
Moisture in CNC air shortens tool changer life
Water in the compressed air supply to a CNC router deposits in the ATC collet mechanism and air bearings over time, causing corrosion and sticking that leads to tool change failures and spindle damage. A refrigerated dryer on the compressed air supply is standard for any CNC installation running production cycles.
-
Sizing for the tool change event
The tool change is the highest instantaneous air demand in most CNC operations: the ATC fires at one moment and draws a burst of air. If the compressor system cannot hold pressure through the tool change event, the collet may not release or clamp correctly, leading to tool misfires or crashes. Size the compressor and tank volume to hold pressure through the tool change cycle.
-
Vacuum holddown: pump versus venturi
A dedicated vacuum pump produces holddown force at far lower energy cost per CFM than a venturi generator running off compressed air. For a CNC router running most of a shift, a properly sized rotary vane or claw vacuum pump pays for itself versus the venturi option within a year or two in compressed air energy savings alone. For occasional or part-time routing, the venturi is simpler but the long-term cost is higher.
Recommended setup for CNC routing operations
For a shop running one to three CNC routers, the setup we install most is a 10 to 25 HP rotary screw compressor with a refrigerated dryer serving the routers and any other shop tools on the same header. The holddown table runs from a dedicated rotary vane or claw vacuum pump sized to the table square footage and the material porosity. For a production panel shop running five or more routers, a larger rotary screw and a central vacuum plant with VSD control match the output to the actual demand. See rotary screw compressors and industrial vacuum pumps for the product options.
When venturi holddown is still acceptable: for a router running occasional
or part-time use on solid material with low porosity, a venturi ejector running off shop air
is simpler to set up and lower in capital cost. The energy penalty is real but acceptable at
low utilization. Past about 40 to 50 percent daily utilization, a dedicated vacuum pump
becomes more economical.
Typical project: CNC router air reliability
Eliminating tool change failures with correct pressure and moisture treatment
A common scenario in this industry is a panel shop seeing intermittent tool change failures and occasional spindle alarms on a CNC router. The root cause is often a small piston compressor running at 100 percent duty cycle that cannot hold 80 psi at the machine during the tool change burst: pressure at the ATC drops to around 60 psi, below the manufacturer minimum for reliable collet operation. A typical project replaces the piston unit with a 10 HP rotary screw compressor and adds a refrigerated dryer. Pressure then holds above 90 psi at the machine throughout the shift, tool change failures stop, and the compressor runs at roughly 60 percent duty cycle with headroom to add a second router. Brabazon sizes and installs the compressor and dryer for this kind of CNC air upgrade.
CNC machine air support across the Midwest
Factory-trained technicians dispatch from 14 branches with an under 2 hour average emergency response. Find your nearest branch:
Questions engineers actually ask us
What size air compressor do I need for a CNC router?
A CNC router typically needs 10 to 25 CFM at 80 to 100 psi for its compressed air functions: spindle cooling, pneumatic tool changes, and chip blow-off. The vacuum holddown table is a separate system requiring a vacuum pump, not a compressor. For the compressor, size from the machine specification plus any simultaneous shop tools, and add 20 percent reserve.
Does a CNC router need compressed air or vacuum for the holddown table?
A CNC router holddown table uses vacuum, not compressed air, to hold parts to the spoilboard. The vacuum is generated by a dedicated vacuum pump, which must be sized separately from the compressed air system. Compressed air is used for spindle cooling, tool changes, and chip blow-off. The two systems are independent.
What PSI does a CNC router need?
Most CNC router air functions run at 80 to 100 psi. Check the machine manufacturer specification for the minimum and maximum operating pressure. The ATC collet actuator typically specifies a minimum pressure to guarantee correct tool release and clamping. Operating below that minimum pressure causes tool change reliability problems.
Why does my CNC router have tool change failures?
Tool change failures on CNC routers most often trace to one of three compressed air causes: insufficient pressure at the ATC during the change event (pressure drop under load), moisture corrosion in the collet mechanism from a missing or failed dryer, or a compressor with insufficient CFM that drops pressure during the tool change burst. Check the supply pressure at the machine under load first.
Can I use one compressor for CNC and spray finishing in a wood shop?
Yes, if the compressor has enough CFM for both simultaneously and the spray circuit has a dedicated coalescing filter and dryer station. The CNC functions do not require oil-free air, but the spray gun does. Separating the spray circuit with its own filtration is the practical solution rather than running an oil-free compressor for the whole shop.
Who services CNC router air systems in Wisconsin, Illinois, Minnesota, and Missouri?
Brabazon has supported woodworking and wood products operations from 14 Midwest locations since 1978. Factory-trained technicians dispatch with an under 2 hour average emergency response and we have been the authorized Sullair dealer since 1984.
Where to go next
Get Your CNC Air and Vacuum System Sized
Tell us your router or machining center model, number of machines, and shift schedule. We size the compressor and vacuum pump from the machine specifications.