Electric motor enclosure?

J. Hoffman

Dealer - Purveyor
I've always used TEFC enclosures for motors, but I have a chance to buy some 1/2 hp TENV motors I was thinking of using for disc grinders. I read that TENV motors are usually hooked up to pumps and use the liquid they are pumping as a heatsink through the shaft to help cool the motor. I'm thinking a big aluminum disk would also act as a heat sink. Also the disk grinders won't be running for hours on end. Does anyone see any issues running TENV motors over TEFC?
 

EdCaffreyMS

"The Montana Bladesmith"
We used these type motors when I worked at a high temp/boiler plant in the military..... these plants are generally used to heat entire military installations. Anyway, we were required to change out the motors every "maintenance cycle" (once a year). All of the TENV motors there were used to run pumps....and had housings to run coolant/water through the bearings. Well, the military being the military, either trashed, or sold the take off motors....so I brought a couple home..... I never tried the aluminum plate....but can tell you without the water running through/cooling the bearings, they lasted about 5-10 mins before the bearings seized..... and then you see those tell tale "temper colors" crawl their way up the shaft...... based on my experiences, they won't last long without water circulating/cooling the bearings...... where as the TEFC (Totally Enclosed Fan Cooled) is just that....and is the type motor most often seen on grinders or other applications where dust/swarf could get into a short out a motor.

That being said, if the motors are cheap or free, I'd say give it a go and see how things go. That way if things do go south, you're not out a lot of $$$.
 

J. Hoffman

Dealer - Purveyor
These are not liquid cooled, and don't have the ability to be. From my reading, liquid cooled are a separate animal, same as fan cooled is different. These are designed to dissipate heat through the shaft and housing.
 

KenH

Well-Known Member
For a disk grinder those should work ok. The problem with overheating that type of motor is when it's constantly working under a heavy load, thus producing heat. For a disk grinder it's seldom going to working at a very low load 99% of time. Only when you're really hogging material which is something that's not normally done on a disk grinder. Since you say these are "low cost" the big aluminum disk will help dissipate heat nicely. I wouldn't pay "lots" for one. Not when a new 1/2 hp, 3 ph motor is available for around $100..... Huh, those are 3 ph? If not I wouldn't consider them. You NEED 3 ph with VFD for a disk grinder, just like for a 2X72 grinder.
 

J. Hoffman

Dealer - Purveyor
For a disk grinder those should work ok. The problem with overheating that type of motor is when it's constantly working under a heavy load, thus producing heat. For a disk grinder it's seldom going to working at a very low load 99% of time. Only when you're really hogging material which is something that's not normally done on a disk grinder. Since you say these are "low cost" the big aluminum disk will help dissipate heat nicely. I wouldn't pay "lots" for one. Not when a new 1/2 hp, 3 ph motor is available for around $100..... Huh, those are 3 ph? If not I wouldn't consider them. You NEED 3 ph with VFD for a disk grinder, just like for a 2X72 grinder.
Yes they are 3ph 1/2hp 56c Marathons. $40 each. My current disk grinder is 1hp but I think these 1/2 hp will work good for the higher grits.
 

Self Made Knives

Well-Known Member
I worked in an engineering lab for a few years at a motor manufacturer. We made a lot of dc motors, brushless dc motors, and servo motors. Almost all of them were TENV motors. A lot of them had thermostat contacts in them that would allow a control to stop the motor if it overheated. Some of them would get so hot on the outside you couldn't touch them. I think the way we usually use disc grinders as knifemakers would be fine for one of these motors.
 

KenH

Well-Known Member
Yes they are 3ph 1/2hp 56c Marathons. $40 each. My current disk grinder is 1hp but I think these 1/2 hp will work good for the higher grits.
I agree 1/2 hp is plenty for a disk grinder - for the way I use one anyway. I've got a 3/4 hp on my disk grinder and don't think I've ever used more than 1/4 hp of it. With my TEFC motor running at 500 rpm the fan is turning so slow you might get almost as much cooling with the aluminum disk for heat sink anyway. I'd buy one for $40, especially if it's 1750 rpm rather than 3600 rpm.

Congrats on finding a good deal
 
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