Standard temperature rated coils use PVC insulated stranded lead wire, UL style 1007 rated for 80°C at 300 volts. It also meets CSA type TR- 64, 90°C at 600 volts; and MIL-W-16878/2, 105°C at 1000 volts. High temperature coils use Teflon Type E, TFE, and meets MIL-W-16878/4A rated at 200°C at 600 volts.
Standard rotary solenoids are lubricated in the ball races and in the sleeve bearing with Nye Rheolube #719L, a lithium soap-based synthetic hydrocarbon grease with wide temperature capabilities from -54°C to over 93°C. The base oil is compatible with most ester-vulnerable plastics and elastomers. It contains a rust inhibitor and an ultraviolet sensitive dye. Endurance engineered solenoids are lubricated with Shell Alvania #2 which is also a lithium soap-based grease with a temperature range of - 29°C to 121°C.
100% copper wire, ULrecognized, single film insulation rated at 200°C (Class H), meets UL file E-37683 or E-34609. Also meets Federal specification J-W-1177/13 or J-W-1177/14. Tubular and Open Frame solenoids use single-build insulation rated at 130°C. It is UL File E-34609 or E-37683 and meets Federal specification J-W-1177/9.
Magnetic Field Intensity
The closed loop integral of this quantity is equal to the total current enclosed, as defined by Maxwells equation. Or, the magnetomotive force per unit length in a magnetic circuit. This quantity is given the symbol H.
See ampere turns.
A bearing used in long life rotary solenoids which is a circle of long needles forming the bearing surface for the shaft.
The starting torque available from the solenoid after subtracting the nominal return spring torque.
(Pulse Width Modulation)
If a solenoid is controlled by a transistor which is signaled from a microprocessor, the PWM can be considered as an alternate means for reducing sizes or saving energy. PWM reduces the effective voltage by pulsing the voltage input. For example, if a solenoid has 12 volts supplied, but at 500 Hz at a 50% duty, the solenoid acts exactly as if it is connected to a 6- volt supply. If the duty cycle is changed to 25%, then the solenoid performs like one hooked to a 3-volt supply. The frequency must be higher than the solenoid can respond to otherwise chatter or humming will occur. Due to the inductive nature of the solenoid coil, the current is smoothed resulting in a constant force. Initially, the microprocessor must leave the transistor on long enough to allow the solenoid to energize. After that point, the microprocessor must alternately issue ON and OFF pulses to the transistor to achieve the appropriate duty cycle.
The ratio of flux density in a given medium to the magnetic field intensity. The symbol used is m and has the value of 4pE-7 in a vacuum.
The ratio of the flux through any given cross section of a given medium (bounded by equipotential surfaces) to the difference in magnetomotive force between the two surfaces.
The magnetic moving component of a linear solenoid, typically made from cold, rolled steel.
Precision Wound Coil
A coil whose individual turns have a prescribed pattern which they must follow during the winding process whereby each turn is laid precisely next to the previous turn. This process allows for the maximum amount of copper in the allotted space. Normally carries a ±5% tolerance on coil resistance.
Random Wound Coil
A coil whose turns are allowed to wind randomly in no specific pattern. One turn may overlap another or may lay side by side or even spiral completely across the surface of the coil. Normally carries a ±10% tolerance on resistance
The ratio of the flux density in a given medium to that which would be produced in a vacuum with the same magnetizing force. Nonmagnetic materials, including air, have a relative permeability of 1, while magnetic materials such as iron, have initial relative permeabilities of around 2,000.
The magnetism which remains in effect on a piece of magnetic material or between two pieces of magnetic material after the electromagnetic field created by the coil has been removed. An air gap is usually maintained between two magnetic poles to minimize the effects of residual magnetism.
Coil resistance tolerances are generally ±5% for heavier gage wires where precision coil windings are used and ±10% for finer gage wire where random winding processes are used. Tolerances are shown for each solenoid in the individual specification charts.
All standard stock rotary solenoids have scroll type return springs. Values range from 1 oz-in to 1 lbin depending on the solenoid size. Tolerance on springs are ±20% of the nominal value shown. Return springs are an available feature on any solenoid.
The ambient temperature range, voltage fluctuation, return springs and temperature rise all affect the net available output torque or force of a solenoid. A 1.5 safety factor should be applied to preliminary calculations of torque or force.
The main axle of the solenoid which runs from the armature through the base and out the bottom and provides the main bearing. The shaft is also used for external attachment to the solenoid. Normally made of non-magnetic #303 stainless steel. On long-life rotary solenoid models the shaft is made of CRS #12L14 or 1215 which has been case hardened in the bearing area for wear resistance.
The small diameter portion of the plunger assembly of a push-type tubular solenoid which protrudes through the base or stationary pole face and provides push capability; usually made from #303 stainless steel.
The cylindrical bearing in the base of the solenoid which provides a guide for the shaft. Usually made from phosphor bronze, it can be made of other materials for different applications requiring longer life.
Sleeving used on standard solenoids to insulate the lead wires where they exit the solenoid case is black Vinylite per Mil-I-631B, Type F, subform Ua, Grade C, Class 1, Category 1, and meets UL file #E13565 and E-18459. Sleeving on high temperature coils is Teflon for temperatures up to 200°C continuous and will meet the requirements of AMS 3655 and UL file #E- 20344 and E-39513.
The torque which is produced by a rotary solenoid in the first degree or two of stroke from the de-energized position.
That portion of any solenoid which contains the coil, case and base. This portion remains stationary during operation.
Coil wrapping tape is clear Mylar brand polyester film 0.002" thick which has been slit to the desired width and is used to wrap the coil in an overlapping manner. The film is per Mil-I--631 Type G, Form Tf, Class I, rated for 130°C continuous and meets UL file #E-39505. Coil banding tape is Mylar polyester film, adhesive backed per Mil-I-15126 Type MFT. This tape is used to wrap around the O.D. of the coil one thickness of 0.0025".