Torque Transducer Under Vacuum

I don't have an answer, but thinking of it, why would it be different? Let's see what the other guys will say...

Wangito.

How much vacuum? If you are into hard vacuum, say 10-8 Torr, you start to worry about materials outgassing, many electronic parts will disintegrate under vacuum. If the sensor has any trapped volumes it may work OK but cause virtual leaks in the vacuum system. Vacuum systems are often baked out before use to remove impurities, will the sensor stand a bake at perhaps 350°C?

As Nigh mentioned vacuum may very well destroy some on-board electronic components and I doubt it would survive a bake-out. If it contains any lubricants at all (besides vacuum grease which has an extremely low vapor pressure) I would seriously doubt that you'd get out of the 10 -3 range if that low. Let's not even go into the chamber contamination from lubricant issue.

The best suggestion I would give is to drop the idea of locating it in the chamber and connect it via a thru-hole fitting if you can make the geometry work.

Hi,

think about a small DC motor (ESCAP, MAXON, FAULHABER) the torque is proportional to current (only friction is to be compensated, and may be temperature as magnetic flux is a function of temperature).

We used these motors - also the ESCAP steppers - in vacuum down to 10-6 mbar.

All needed baking (at allowable temperature of coil and magnet and maybe bearing), so if temperature is an issue (in most vacuum systems if hard vacuum) then try to get a motor with SmCo magnets (small TC) and class H or C insulation (200 resp. 230°C max. temperature and duroplastic).

If you use an available torque sensor then look at the specs of the measurement system that is used. Most often inductive it may be bakeable. Better if capacitive then removal of active part of electronics will bring bake temperature to any desired level. Electronics to be baked separately at low (120°C) temp.

I once had big problems with the residual porosity of a magnet that resulted in continuous outgassing (we stopped the outgassing measurement after 2 months of test).

RHABE

Thanks for the advice! We won't be baking out the system so that shouldn't be a problem. The vacuum pressure will be 10-5 torr or lower.

Hi,

if 10-5 torr or lower, you will need baking, minimum at 120°C, else you will have very long pumpdown times.

A new chamber or after any major changes or after any contamination it is highly recommemdable to bake for 24 hours!

Try and see yourself.

RHABE