Mfg. suggestion for centrifigual blowers

We have centrifugal blowers that generate vacuum for our palletizing robots' suction cup grippers. We have expereinced several failures recently, one of which is not repairable and the availability date on a new replacement is some time in November.

I was asked to find another supplier for a quicker replacement. The repaired blower that was installed yesterday is already making noise, and could fail any minute.

They are 5HP 3450rpm centrifugal blowers. I will have to dig up the numbers for CFM and inlet/outlet sizes...

Can anyone suggest a good brand to look into?

Thanks in advance.
Paul

Back a few years ago I worked in a plant that used a blower to transport gypsum, I found out then that many are very susceptible bearing/seal damage if the input is not properly filtered.

Yes, we have good filtering in place. The latest word I just heard is that we may have destroyed one of them due to cavitation. There is a vacuum relief valve that may have malfunctioned...more to follow...

EDIT: The relief valve checked good, and there are vacuum zones always open when the robot is idle, so I guess it's just a case of worn out blowers, been rebuilt too many times...

OkiePC said:

They are 5HP 3450rpm centrifugal blowers.

Click to expand...

Paul are they centrifugal or regenerative (ring compressor)?

Just my opinion, and it may not be possible in your case, but I woud use Venturi type vacuum generators, (just ignore this if you dont have compressed air availible). Also can you not monitor with a pesssure switch the amount of vacuum being generated, as the vacuum diminishes you could call an alarm up to state that your sytem needs attention.

Check out

http://www.rietschlepumps.com/home.htm

One of my customers uses these and likes them a lot...

John

Siemens make some good units (ours are on vacuum fillers). Although I agree with the venturi generators, we use these quite a lot (Festo) and there is a massive number of options for gripping with different cup's etc avaliable.

Thanks for the feedback. The boss says no to air powered vacuum generators, they had those at first and they were more trouble.

Right at the end of shift yesterday, I found that the VFD controlling the motor was set for 80Hz. I changed it to 60 and the noise dropped significantly. This morning, the thing is quiet again. I guess that it created its own clearance.

Our distributor now has a new unit on the way due in tomorrow, so it's not a hot issue to find another brand now.

The story behind this failure is quite entertaining.

The blower sits on a Fanuc M410i robot base, and would only whine when the robot Axis 1 was turning clockwise (when viewed from above) at a speed greater than 45%. Very weird. I wish I had videotaped it. For the first two hours of troubleshooting, we thought it was the robot's Axis 1 reducer, but that checked out okay. We even changed the lube in it looking for metal shavings.

Apparently, someone in the past changed the speed of the drive to compensate for bad vacuum cups or low quality cardboard.

Why a VFD? Well, when the robot picks up slip sheets, the vacuum is too great and it tries to carry a whole pile of them, so the VFD provides for a reduced speed during slip sheet pickup.

Vaccum Blowers

I have used Gast blowers for high flow / low pressure applications. Maybe they have something for your application.

http://www.gastmfg.com/blower.html

Vaccum is just negative pressurized air so you can still use a regulator. I think I would rather do that then have the motor be adjusted.

Sounds like you may need to monitor the motor and vacuum in some manner.