Motors That Survive
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LAB NOTES

LAB NOTES is a newsletter we have developed to meet the needs of the research and lab-oriented design engineer who has specialized needs for motion control components.

Empire Magnetics' customers usually have unique motor needs. Often, they require motors that will function reliably in environments that are hostile to standard motors... Different models in our line of 1.8° hybrid permanent magnet stepping motors and brush-less servo motors are qualified to withstand the effects of vacuum environments, radiation, extreme temperatures (including cryogenic), dust and abrasives, and also perform when submerged in liquids.

LAB NOTES will explore the hostile conditions related to vacuum and radiation resistant motors and resolvers.

Did You Know?
Selected Special Interest Articles
From Weapons to Wind Power
Empire Magnetics Partners with State Rocket Center to Design Low Maintenance Wind Power Systems
Specialty Motors for Corrosive Environments
Motor Selection for Deep Sea Applications
Motors for Positioning in Vacuums
Motors in Radiation-Intensive Environments
Radiation-Hardened Motors	ORNL Develops Fuel Pin Dissolver with Empire's Radiation-Resistant Motors
Semiconductor Manufacturing Requirements	Drive New Automation Technologies
Motor Designs To Survive Hostile Environments
Using Purge and Pressurization to Prevent Explosions
Step Motors in Space Applications
Waterproof Step Motors Make Waves in Industry

Vacuum Motors, In-Use:

..1.	. .	U.C. Berkeley Space Sciences Lab: satellite testing
..2.	. .	U.C. Santa Cruz, Lick Observatory: telescope instruments
..3.	. .	Arnold A.F.B.: cryogenic motors and resolvers for test equipment
..4.	. .	Optical Coating Labs: space optics cleaner
..5.	.m .	Boeing: air lock controls on space station
..6.	. .	Smithsonian Observatory: space based telescope equipment
..7.	. .	Stanford Linear Accelerator: beam line adjustments and experiments
..8.	. .	J.P.L./Hughes: Satellite testing facility
..9.	. .	Space Industries: Solar panel positioners on Wake Shield satellite
10.	. .	European Space Agency: satellite based scintillator calibration
11.	. .	CTA Space Systems: satellite inertial guidance adjustment
12.	. .	NASA/Langley AFB: wind tunnel controls
13.	. .	Argonne National Labs: servo systems for beam line

Rad-Hard Motors, In-Use:

..1.	.....	General Electric Nuclear Fuels Division, San Jose: motors to operate reactor inspection equipment
..2.	.....	General Electric Wilmington facility: motors for an X-Y control system
..3.	.....	Martin Marietta/Oak Ridge National Laboratory: step motors and brushless servo systems for fuel reprocessing system
..4.	....	Stanford Linear Accelerators: motors resistant to radiation from particle beams
..5.	.....	Tokai Works, Japan: motor, gearbox and resolver system to drive portion of fuel reprocessing system
..6.	.....	Taiwan Nuclear Power Commission: step motor & gear-box for use in hot cell robotics system
..7.	.....	Public Nuclear Commission, Japan: variety of motors, motor brakes, motor gearboxes and resolvers
..8.	.....	Ontario Hydro, Canada: stepper motor for use in a hot cell
..9.	.....	Los Alamos National Labs: rotor nut motors for use in focus mechanism in Mu Meson facility
10.	.....	Brookhaven National Labs: motors for 'down hole' testing

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Did You Know ?

• That teflon breaks down very quickly when subjected to gamma radiation?
  
  Under massive doses, teflon can be made to vaporize so rapidly that a toxic gas cloud is created.

• That Teflon recovers well from low temperatures?
  
  Teflon-insulated wires used at 20°K can be cycled to and from room temperatures without significant damage.

• That Teflon works well in a vacuum, and that its vapor pressure is similar to many metals?

• That Teflon is subject to "cold flow" and is not a good choice for machined parts when accurate dimensions must be maintained?

• That Empire Magnetics has supplied its specialized motors for satellite applications?
  
  One of our motor gearbox assemblies is mission-critical. The motor rotates the platform to orient the satellite antenna arrays. We are also supplying other, much smaller motors to the European space agency.

• That the power of a motor cannot be increased by adding a gearbox?
  
  Power is the multiple of speed times torque. Since a gear ratio will multiply the torque, but divide the speed, the only effect on total power is the reduction caused by the inefficiency of the gearing.

• That dry 'lubes' react in different ways to airborne moisture?
  
  Graphite requires moisture to lubricate, for instance. Molybdenum disulfide, however, absorbs moisture and degrades quickly. This is one reason why graphite is a poor vacuum lube and MSO₂ is often used instead.
  
  There are many processes for applying MSO₂ (or similar dry lubes): spraying it into the bearings is the method used for larger bearings (where clumps of lube are not significant); binders are used to "paint" the dry lube onto the metal surface; impingement is used to "hammer" the dry lube to the surface; flame plasma is used to fuse the material to the metal.
  
  The latest approach for applying dry lube is ion implantation, or deposition. None of these methods is without flaws, but the ion implant technique does seem to be best for instrument grade bearings for high precision applications.

• That the life of a stepper or brushless motor is limited by the life of the bearings and the thermal life of the insulation materials?
  
  Most motors fail not due to the end of the motor's life, but because they are misapplied or have been abused by the people using them.

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