Author Topic: Laser cutter ventilation dimensioning  (Read 1069 times)

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Bootcat

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Laser cutter ventilation dimensioning
« on: October 11, 2017, 03:13:33 AM »
Hello all,

I've been cutting with a 1600x1000mm 130W laser for a month now (Bodor 1610 if you ask).
The supplied ventilator was weak so I found myself a 1,1kW/230W ventilator with 1100Pa of pressure. Better but still no suction on, say a 1500x1000 1,5mm PEHD sheet that's slightly warped.
How do you guys choose ventilators? Is there a formula for calculating the correct depression?
Also, do you use secondary ventilators to extract the air from over the table (I have an exhaust tube under the table and another one over it)?

mogensbeck

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Re: Laser cutter ventilation dimensioning
« Reply #1 on: October 11, 2017, 04:08:38 AM »
As I remember then you need a fan that can make over 3000Pa for that size of machine.

You can contact an exhaust company and they can do the calculations for you and what filters to use.

Mike9386

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Re: Laser cutter ventilation dimensioning
« Reply #2 on: November 15, 2017, 12:33:30 PM »
I have Bodor 1600x1000mm aswell and i disconected that fan and pluged my BOFA AD PVC Iq extraction unit which can easily grab every smoke. This BOFA helps also with Chlorine in case you are cutting Hypalon or any PVC stuff.

Bootcat

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Re: Laser cutter ventilation dimensioning
« Reply #3 on: November 16, 2017, 01:58:11 AM »
Thanks Mike9386, this is just what I needed to know. Since I don't cut TPU/Hypalon the simpler Oracle iQ should be adequate but I'll ask the distributor.
Bonus question: did you connect the upper exhaust tube to the extraction unit? It's not clear to me if I need a T connection and a valve between the exhaust tubes or if I should simply connect the lower to the extraction unit.
Also, do I still need to extract the air outside of the production room with such filters or can it work indoor? I'm worried about extracting hot air from the room in the winter.

A useful trick in exchange: if you take off the air flow regulation valve and directly plug the pipe into the laser head your airflow will greatly increase, effectively pushing most fumes below the table. The valve has a max diameter of only 1mm which bottlenecks the compressor airflow.

Stone

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Re: Laser cutter ventilation dimensioning
« Reply #4 on: November 16, 2017, 06:38:42 AM »
If you really want to minimize the removal of warm air from inside the room (aka cutting during the winter, for those of you who live in areas where it gets cold enough to snow), then you would need to put the laser in its own room. Be careful though, as laser tubes (especially glass) have a MINIMUM working temperature. If it gets too cold, thermal shock can crack the tube. Running a supplementary room heater can help, but unless you're sucking in air from another place, having a draft in the room will be the only way I'm afraid. Air exchange in the laser bed is critical, especially when cutting fabrics that contain chlorine. Get as much suction as you can, exhaust thone fumes out of the machine asap.

Bootcat

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Re: Laser cutter ventilation dimensioning
« Reply #5 on: November 16, 2017, 07:02:27 AM »
Thanks - it will be the first winter in this location so I expect surprises. The laser has its own room. I suppose I'll need to add glycol to the water circuit and/or a heater inside the machine to keep the tube at a correct temperature later on.
For some reason the good people at the CNC forum never answered my ventilation questions so I'm happy to get some input here  :).

Stone

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Re: Laser cutter ventilation dimensioning
« Reply #6 on: November 16, 2017, 09:17:47 PM »
If you can pick up a warmer/chiller unit to keep your laser tubes water at the proper temperature, I doubt you'll have much problem. If you're venting outside, consider adding a "blast gate" to your ducting so you can keep outside air from coming inside when the laser is not in use.

EBay has proven to be a good source for water bath stabilizing units for me in the past (used for keeping photography chemistry at the right temperature), not sure if things would/could be different in the EU, as I'm in the states. IDK if glycol would be necessary if the laser room is kept at a stable enough temperature 24hrs/day through the cold winter months.

-Dan

WhiskeyTwoFour

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Re: Laser cutter ventilation dimensioning
« Reply #7 on: November 17, 2017, 10:09:12 AM »
What's the flow on the 1100Pa fan?

Bootcat

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Re: Laser cutter ventilation dimensioning
« Reply #8 on: November 28, 2017, 12:46:41 AM »
No idea..

WhiskeyTwoFour

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Re: Laser cutter ventilation dimensioning
« Reply #9 on: November 29, 2017, 05:25:43 PM »
No idea..

***ALWAYS CONSULT THE MANUFACTURER(S) FOR YOUR APPLICATION***

Pressure (Pa, mbar, PSI, etc) and flow (CFM, m^3/hr, liters/min, etc), for this discussion, are meaningless without each other.

If you're looking to flatten a sheet against the cutting table, maximum flow and pressure is good a start.  Of significant importance too is optimizing and sealing ductwork internally and externally.

An Oracle iQ is rated at 96mbar (9600pa) and 380m^3/hr (223CFM).  For a 600mm / 24in class laser, that's on the weaker side for fume extraction and probably won't offer enough suction for flattening much of anything.

On a 60" / 1600mm cabinet class laser, 1275m^3/hr (750CFM) at 100mbar (10,000pa) would be the minimum for me to feel safer with fume extraction.  That's in a space with good airflow and high ceilings.  In an enclosed space, I'd prefer a minimum of 1000CFM (1700m^3/hr) at 100mbar (10,000pa).  For consistent flattening force, it may require more.

Remember that even if enough suction force is present to flatten the sheet, parts may curl as they're cut.  The sheet will be less airtight against the table.  Then the rest of the uncut sheet curls again.

Have you checked with a distributor to see if they offer varying grades of flatness?

Have you considered a clicker press?  Lasers are definitely not the cutting solution for every application.

***ALWAYS CONSULT THE MANUFACTURER(S) FOR YOUR APPLICATION***

Bootcat

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Re: Laser cutter ventilation dimensioning
« Reply #10 on: November 30, 2017, 02:29:00 AM »
I'm currently consulting with BOFA distributors about the best system to use. Was initially looking at an Oracle SA or Oracle iQ - with your data above I'll ask whether it's enough.
I've asked the current blower manufacturer about the detailed specs to have a baseline.
The sealing work is done already.