By Michael Stuart - 8/3/2019 8:13:36 PM
I own a small fabrication shop, and we do a very wide range projects that include light production of out-of-autoclave prepreg parts, resin transfer molding, veneer laminating under vacuum, among other things.
I’m looking at some pumps and wonder if anyone has personal experience as to how they would fit into the work we’re doing.
I’m currently running a 7 cfm oil rotary vane pump that is getting down to 230 microns (.23 torr or 29.9 inHg) but with some of the larger projects it is inevitable that there are losses in the system that a better pump might help mitigate. When infusing low viscosity epoxy into a 120 sqft layup, the flow curve of my current pump will not saturate the project fast enough, or without loosing all of the debulking.
I’m looking at these pumps:
Welch 1376
Leybold NT10
Leybold D16AC
Edwards E2M28
Any information on these or suggestions on other pumps would greatly appreciated.
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By explorecomposites - 12/20/2019 8:31:13 PM
For general purpose stuff, I would really suggest you get two separate pumps - even if it means you buy them used. The activities you describe suggest that you need a medium sized high-vac pump - 2hp or so and also a similar sized (or bigger) dry rotary vane pump.
The pre-preg as well as the infusion debulking and resin feed steps really require low capacity high vacuum pumps. For the curing time (from when you clamp the resin infeed) of the infusion you want to dial back the vacuum and throttling or bleeding air into a oiled rotary vane pump will not work well in the long run. Also for veneering a low-vac (150mbar / 25inHg+) dry pump is perfect.
Once nice thing about some of the Busch, Becker, Gardner Denver pumps I have used is the exhaust filter which keeps oil out of the air (condenses and recirculates it) when you're sucking down bags or doing high flow-through stuff. Never a bad idea to plumb pump exhaust outside though!
I wrote a post about vacuum pump choices - it might be helpful:
https://explorecomposites.com/articles/tools-and-equipment/buying-a-vacuum-pump/
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