There is a wide discrepancy between the levels of vacuum that different types of vacuum pumps and blowers can generate. Some kinds are rotary screw pumps, liquid ring pumps, rotary vane pumps, positive displacement blowers like a roots blower, or regenerative blowers (which are more like a fan). You need to consider both the level of vacuum you need to attain and the amount of air you need to move to get there. Compare a 10HP regen blower, vs a 10HP rotary vane pump. The regen blower can move 4 times as much air as the positive displacement vane pump. But the vain pump can draw more than twice the vacuum level. Which would hold a part better will depend a lot on table design and area. An open hole table with small pockets over the holes can work very well with the blower, but the blower will struggle trying to hold small parts on a fall board. The vane pump would work great on closed pods and jigs or a smaller fall board, but if the table is very large or an open flow design it won't be able to keep up and vacuum levels could fall too low.
A 5ft x 10ft fall board (sheet of MDF that has been skinned can flow nearly 300acfm (maybe a bit more) of air when a 15inHg vaccum is applied to it. But if you need 20inHg to hold your parts, you're going to need a much larger and more powerful pump to get there (probably at least double). But if you only need 10inHG the flow through the board will be much less probably closer to 100ACFM. The greater the pressure differential the higher the flow and leakage. This is why gasketed jigs and pods work so much better for holding pieces. You don't have the flow to contend with, you only need a pump capable of generating the pressure level you need and the ACFMs of the pump are less important. Todd Zuercher P. Graham Dunn Inc. 630 Henry Street Dalton, Ohio 44618 Phone: (330)828-2105ext. 2031 -----Original Message----- From: Les Newell <les.new...@fastmail.co.uk> Sent: Wednesday, June 09, 2021 2:42 PM To: emc-users@lists.sourceforge.net Subject: Re: [Emc-users] OT: About a chat here on vacuum table ideas [EXTERNAL EMAIL] Be sure links are safe. I tested a 1.5kW vacuum cleaner motor for this application a while back and wasn't impressed. They don't generate enough vacuum in my opinion. You really need vane pumps or side channel blowers. Vane pumps generate a very strong vacuum but use a lot of power. Side channel blowers generate more flow for the same power but less vacuum. I used to operate a machine with a 1.2m x 2.4 bed that had two 2kW side channel blowers and the vacuum was marginal. I did have parts move occasionally. Les On 09/06/2021 16:31, Roland Jollivet wrote: > A friend was complaining about the need for 6kW vacuum system on a > large table and this got me thinking.... > > Another way is to divide the table up into squares, grid wise, and > have a .. separate.. vacuum motor for each section. The motor is > mounted under the table at the bottom of each 'box'. > You can get ~1.5kW motors really cheap, and now it's easy to make up a > system with as many kW as you want. > > Far easier to find 4 vacuum motors than a 6kW pump. > > Roland > _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users