Advice on having a custom fan made?

[mrpi]

I'm designing a custom motor for an industrial grinder.

This is a brushless servo motor intended to replace a synchronous AC motor.

Due to mounting constraints, I would like to install the cooling fan on the non-drive end of the motor shaft. All my previous experience is defense products in which the customer supplies a specified CFM of cooling air thru a duct to cool the motor.

I honestly have no idea what my options are as far as the fan blades themselves. Is it common to have a fan bent, cast, or injection molded for something like this? Then do you put them in a duct to characterize/verify the flow rate?

Motor speed is 6000 rpm or higher, so I was worried about using the fan that is supplied on the back of Baldor or other synchronous AC motors.

I'm designing the fin/heatsink arrangement on the motor housing, so I have control over the pressure drop.

Originally I was looking at using an axial fan, maybe even an automotive engine cooling fan, but I have no idea what kind of flow rate they produce. But I can find them rated to 10k rpm. It appears that most synchronous AC motors use radial fans and a curved shroud to turn the air so it blows down the body of the motor.

OD is in the 10~14" range.

My feasibility study shows I need around 200~300 cfm which equates to less than 0.25 inH2O pressure drop thru the fins.

Do I have a fan custom made?

Beat to fit, paint to match.

 

[MintJulep]

Find a fan manufacturer and give them you requirements. Don't try to design a fan yourself.

 

[Dougt115]

Buy it. Your CFMs are not that high and you have a large diameter. If you try to use that 6000rpm you're going to have to gear down or you will kill someone with the ninja fan (it will break off the blades and throw them like throwing stars).

 

[willard3]

Tell your jefe that you don't know how to design fans and then find someone who does.

 

[FredRosse]

Just have a look at a TEFC motor, that picture will be worth a thousand words.

 

[mrpi]

MintJulep, I emailed Rotron, and they said the pressure is a little low for their products and recommended a couple other fan mfg.

Dougt115, I doubt I'll be able to gear down due to the cost of a gear reducer. But I have seen a blade come off a Chevy fan and cut a hole in the hood, so I hear you about the ninja fan...

Willard3, I'm taking that exact path!

FredRosse, I was just reading a couple PDF's on TEFC motor fan characterization. My main problem is I'm trying to run at 2x the speed of most of those types of motors. I would really like to be able to just buy a TEFC replacement blade set and be done with it.

Thanks for the replies folks!

Beat to fit, paint to match.

 

[ScottyUK]

Many motors designed for use with VFDs are fitted with an auxiliary blower. Is this an option? You can probably find one ready made as an aftermarket spare from one of the big brands.