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New Facility Advise/Questions

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Hi all, Our new SMT adventure has been quite successful, an... - Dec 17, 2019 by kyleh04  

#83974

New Facility Advise/Questions | 17 December, 2019

Hi all,

Our new SMT adventure has been quite successful, and are planning a move into a new building. It will be ~4000 sqft, mostly for the SMT line, with some offices for design work.

We currently have a Opal pick and place, DEK printer, and a heller 1500 oven. Our main reason for the move is for more space, and to allow us to do through hole and lead-free work. So we will be adding a Heller 1809 oven, and a (unknown brand yet) wave or selective solder.

We will be keeping the 1500 oven to use as a backup or batch oven for one off jobs. We will eventually turn that oven into another smaller line. This line will be geared for super small batch or prototype runs. It will probably have a MyData machine, and will use our DEK, when we upgrade it.

I have a drawing attached with the rough floorplan that we have been working on. Anything that says "(future)" is something the we will add on later. Units are in feet, bottom left corner of page, is corner of wall.

Both lines will(are) left > right, so for the main one, we will operate it in between it, and the tables against the wall.

We plan on adding SPI/AOI to the main line, with the oven staying put, and the rest shifting downward.

Question:

1) Landlord wants fewest holes in the roof/wall. Is it possible to have a single large duct out the roof, with a large fan on it. Then splice it out to various machines, and use a valve to allow flow to each? Or does each machine need separate exhaust?

Let me know any thoughts or suggestions you may have, or if you need any clarifications.

Attachments:

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#83978

New Facility Advise/Questions | 18 December, 2019

People still cut holes in the roof for process venting? Where do you live? Montana?

Three companies that support SMTnet want you to consider their fume extraction equipment:

* Metcal

* ShenZhen J-wide Electronics Equipment Co.,Ltd

* PACE Worldwide

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#83979

New Facility Advise/Questions | 18 December, 2019

I'm not sure if I follow? Was there sarcasm?

We are in Florida. We currently use a purex filtration unit. The issue is that it pumps out so much hot air that it heats up our space too much.

Everyone I've talked to vents outdoors who live down here, since it's already so hot outside.

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DWL

#83980

New Facility Advise/Questions | 18 December, 2019

I worked at a similar sized facility in Texas, and we had everything connected to one vent and exhausted outside. A word of advice; Your outside vent will leak in heavy rain, don't put it over any equipment.

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#83981

New Facility Advise/Questions | 18 December, 2019

> I worked at a similar sized facility in Texas,
> and we had everything connected to one vent and
> exhausted outside. A word of advice; Your outside
> vent will leak in heavy rain, don't put it over
> any equipment.

Ahh yeah that worried me.. We have easy access to an outside back wall, which is covered, I think we'll just go through that instead of the roof.

Do you know what size duct was out the roof? And what the fan was rated for cfm wise? Also, what and how many machines were on that line?

Sorry for all the questions! Thanks.

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DWL

#83982

New Facility Advise/Questions | 18 December, 2019

We were using a heller 1500 and an electrovert minipak wave solder. I don't recall the duct width or CFM. 6"-8" maybe? Probably want to over size it a bit as its easy to turn the fan down if you start sucking out the AC.

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#83988

New Facility Advise/Questions | 19 December, 2019

Where do you live that most people aren't cutting holes in their roof?

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#83992

New Facility Advise/Questions | 19 December, 2019

Even here at SF bay area, we also cut holes at the roof. We just moved to a new facility building 3 months ago.

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#83993

New Facility Advise/Questions | 19 December, 2019

So how'd you do it? Each machine has a separate hole? Or all piped to one?

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#83994

New Facility Advise/Questions | 19 December, 2019

We opened 2 separate holes at the roof. 1 for the SMT 2 reflow ovens to share; another 1 for the wave soldering.

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#84004

New Facility Advise/Questions | 20 December, 2019

Yeah, I can't imagine our AC having nearly enough head room to handle that additional heat load in the summer.

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#84007

New Facility Advise/Questions | 20 December, 2019

OK great! Seems like there's (mostly) a consensus on the ducting outside, and it seems like the multiple units to one duct is doable.

What are you thoughts on the floorplan/layout then?

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#84008

New Facility Advise/Questions | 21 December, 2019

You can use one but over spec it. It will be a non-linear problem to figure out how much each exhaust port exhausts. Also have lots of shut off valves to shut off exhaust ports that you are not using. We have some holes in the walls in the back of the plant because cutting holes in the roof has a large liability cost. Did I mention that you should over spec the exhaust? Not just for possible future expansion but also because the exhaust port farthest from the final exhaust will have the least effect.

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#84019

New Facility Advise/Questions | 23 December, 2019

I would suggest having both SMT lines next to each other rather than separate by tables, worst yet, another big machinery. You might not have the machines yet for those empty line#2 space, but you can use it as a temporary storage area until then. Once big equipment settles in, you don't want to keep moving them around again (rebalance and alignment is not fun). Try to plan ahead if you have time to do so, once you moved into the new building, it's not easy to rearrange the way you wanted.

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#84021

New Facility Advise/Questions | 23 December, 2019

> I would suggest having both SMT lines next to
> each other rather than separate by tables, worst
> yet, another big machinery. You might not have
> the machines yet for those empty line#2 space,
> but you can use it as a temporary storage area
> until then. Once big equipment settles in, you
> don't want to keep moving them around again
> (rebalance and alignment is not fun). Try to plan
> ahead if you have time to do so, once you moved
> into the new building, it's not easy to rearrange
> the way you wanted.

Not moving equipment twice makes sense. But why do you like both lines next to each other? I figured having the tables there helps for part and reel storage and loading. We don't plan on using the second line for large production, only for prototypes, quick turn times, backup, etc.

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#84022

New Facility Advise/Questions | 23 December, 2019

There are times you might want to move the job from one line to another in the middle of the run; ie. machine down. Currently, our SMT is set up like yours, line#2 is just for simple/prototypes jobs. It's easier for us to moves the job from line#1 to line#2 if we want to free up line#1 to start another mass production job. Do you really need a long line of tables at SMT? We prefer to use moveable storage shelves instead. 1 table at the front/back would be fine, at least that works for our facility.

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#84032

New Facility Advise/Questions | 26 December, 2019

If you're going to vent through a single exhaust/fan combo, I would recommend spending the money, and getting an HVAC company in there to size the exhaust fan, and duct work. It'll pay dividends for you in the future.

We did that at a previous company, and, as it turned out, our reflow oven and selective solder had very specific air-flow requirements. Having the HVAC guys available to calculate system airflow demands, create a plenum with filters, and correct duct-sizing/baffling made it a lot easier for my planning than me trying to do it.

Cheers, ..rob

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#84037

New Facility Advise/Questions | 27 December, 2019

> If you're going to vent through a single
> exhaust/fan combo, I would recommend spending the
> money, and getting an HVAC company in there to
> size the exhaust fan, and duct work. It'll pay
> dividends for you in the future.

We did that at
> a previous company, and, as it turned out, our
> reflow oven and selective solder had very
> specific air-flow requirements. Having the HVAC
> guys available to calculate system airflow
> demands, create a plenum with filters, and
> correct duct-sizing/baffling made it a lot easier
> for my planning than me trying to do
> it.

Cheers, ..rob

Yeah, I've thought of having an hvac company assist. It's tough because most oven manufacturers don't even specifically tell you the cfm they need. Heller says that 300cfm is good, but even if it is lower, if it passes the tissue test, then it's fine.. Lol.

Other thing with hvac, is their cfm calculations are bizzare. Based on this https://www.engineeringtoolbox.com/equivalent-diameter-d_443.html

We would need like a 8" diameter duct for 300cfm, which for exhaust purposes, is dead wrong.. We have a 4" exhaust currently for our purex filtration unit, and full power it is over 400cfm, measured at the oven with an anmeter..

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#84039

New Facility Advise/Questions | 27 December, 2019

"We would need like a 8" diameter duct for 300cfm, which for exhaust purposes, is dead wrong"

If you have 2 4" exhaust ports on your oven (some do, some don't), an 8" or larger main trunk might be justifiable, especially if you have another machine on the same line. All of that depends on how long the runs are, how many fittings and bends there are, etc..

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#84043

New Facility Advise/Questions | 27 December, 2019

yeah...I never had airflow volume problems with Hellers.

When I had to build the system I was referring to, we had an old Speedline oven, and the way it was configured if you didn't provide enough airflow to the outer cavity, the blowers would overheat during operation. We had the exhaust on this tied into the same line as our KISS selective solder, which had a required flow rate of something ridiculous like 4CFH (I think it had something to do with the recommended N2 flow rate). If the natural airflow got too out of control, we either burned N2 like it was going out of style, or wound up with crud on the nozzles really really quickly.

We ended up with an 800CFM exhaust fan with, I think, an 8" duct down to a plenum with HEPA filters, and then 4" duct work (with baffles) to the Speedline and the KISS. The baffles weren't enough for the kiss, so, we ended up with duct tape over the exhaust tube with a hole punched in it.

You can drive yourself crazy trying to do HVAC calculations . Process variation in reflow is easier to calculate :D Different duct sizes/plenums create pressure differentials throughout the system, which directly impacts CFM flow rates. Every time you reduce your duct size, you increase system pressure, which will impact CFM. I swear for our system we should have bought a 1200CFM exhaust fan (leaving some overhead for future expansion); but, I was assured that the 800CFM fan would take care of it between the plenum and duct size reduction (and the particulate and charcoal filtering we were doing). In the end, I was happy my boss told me to have someone else do the math!

cheers, ..rob

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#84051

New Facility Advise/Questions | 28 December, 2019

> yeah...I never had airflow volume problems with
> Hellers.

When I had to build the system I was
> referring to, we had an old Speedline oven, and
> the way it was configured if you didn't provide
> enough airflow to the outer cavity, the blowers
> would overheat during operation. We had the
> exhaust on this tied into the same line as our
> KISS selective solder, which had a required flow
> rate of something ridiculous like 4CFH (I think
> it had something to do with the recommended N2
> flow rate). If the natural airflow got too out
> of control, we either burned N2 like it was going
> out of style, or wound up with crud on the
> nozzles really really quickly.

We ended up with
> an 800CFM exhaust fan with, I think, an 8"
> duct down to a plenum with HEPA filters, and then
> 4" duct work (with baffles) to the Speedline
> and the KISS. The baffles weren't enough for the
> kiss, so, we ended up with duct tape over the
> exhaust tube with a hole punched in it.

You can
> drive yourself crazy trying to do HVAC
> calculations <lol>. Process variation in
> reflow is easier to calculate :D Different duct
> sizes/plenums create pressure differentials
> throughout the system, which directly impacts CFM
> flow rates. Every time you reduce your duct
> size, you increase system pressure, which will
> impact CFM. I swear for our system we should
> have bought a 1200CFM exhaust fan (leaving some
> overhead for future expansion); but, I was
> assured that the 800CFM fan would take care of it
> between the plenum and duct size reduction (and
> the particulate and charcoal filtering we were
> doing). In the end, I was happy my boss told me
> to have someone else do the math!

cheers, ..rob

Not sure I'm following your setup..

You have a common plenum where all of the fumes go, then the air from that plenum is pumped outside? Are the filters pumping some of the dirty plenum air back into the workspace? Why not just duct the air straight outside?

Our plan is to have our plenum air conditioned, and several fan filter units pumping that conditioned air down to our space, keeping the room relatively clean.

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#84114

New Facility Advise/Questions | 6 January, 2020

Kyleh04,

I worked for one place that used the vent inside the building. You end up with a lot of heat, smell and increased number if defects(because of the heat in the building). Based on the debit of your machines you can can combine them and use a fan powerful enough to vent all out. Most machine manufacturers will help you with this calculation.

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#84115

New Facility Advise/Questions | 6 January, 2020

We wanted to filter the exhaust from the oven and selective solder...so, the ducting from the machines went into a common plenum that contained both a particulate filter, and a HEPA filter. That plenum exhaust was connected to a roof fan that vented the whole system.

Cheers, ..rob

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#84116

New Facility Advise/Questions | 6 January, 2020

A lot of people also assume that the filtration is for cleanliness of the gasses that are leaving the plant, and that is not the case.

I helped spec. (like you, Rob, I let someone else do the math) a system like yours, with a single common main trunk pulling from 3 reflow ovens with a filter box at the union. That filtration system kept the vast majority of the gooey flux condensation out of the main trunk and the blower on the roof, which probably extended it's life significantly.

We had dampers in several locations and measured flow rate regularly but saw very little variability once it was all set up. As you can imagine, plugged filters reduce flow so you do have to stay on top of that.

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