Application Notes On Use Of Miniature Solenoids

We can evaluate your requirements and determine the proper solenoid for your application. Please fill out and return our Engineering Data Sheet.

Perhaps the most important consideration in the use of minature solenoids is the force vs stroke. To determine the correct solenoid it is first necessary to determine what force is required to move the work load. Second what is the travel required to move the load.

Example: A force of 20 oz is required and the length of travel required is .070. By the use of our force charts you can determine that this can be accomplished by the following means:

  1. SP-75 used in continuous duty cycle will do the job.
  2. SP-62 used in a 25 percent duty cycle will do the job.
  3. SP-50 used in a 6 percent duty cycle will do the job.

This gives you three choices. You must determine 3 additional factors:

  1. The size of solenoid you require. You have three options, Above.
  2. The duty cycle of operations. Again you have three options.
  3. The power source available to operate the solenoid, voltage and current. This may be a determining factor on your choice.

After you have made your optimum choice of solenoid, there are several other factors that must be taken in consideration:

  1. The ambient temperature of operation. The force curves are shown at 25 degree C. The normal rise in temperature of the solenoids is 85 degrees C. above ambient. Therefore, the percentage of force is determined by temperature chart shown in catalog. For normal operation with some kind of heat sink, the operating temperature is approx. 105 degrees C. This means the force at hot is 78 percent of the force shown on the curves. Please take this deration into consideration especially where continuous duty is concerned.
  2. The reaction time desired. It is obvious that the smaller the solenoid, theless mass to move, therefore, faster reaction time. Secondly, the shorter the stroke the faster the reaction time. Third, a solenoid operated at intermittent duty with 4X voltage applied will be apporximately four times as fast.
  3. Life of the solenoid. In many cases, the life required is beyond the normal life specified. Several extra features can be added to increase the normal life. I f you anticipate over 2 million operations it would be well to take into consideration the extra features.

Our solenoids are designed for optimum performance for the size of the units. It is oftened asked if we can add more turns to increase the force. This process is self defeating. In the increased resistance due to the additional turns of wire reduces the current. Our materials are the best available in the industry. However, there are several ways to increase the force other than changing the coil.

  1. Shorten the stroke.
  2. Use intermittent duty cycle or pulse the unit.
  3. Use the next larger size solenoid for higher wattage.
  4. Consider the use of conical plunger for additional forces at between .050 and .125 stroke.

After the proper solenoid has been chosen, then you should consider the design options as to mounting, terminals or leads, and special features you may require or desire us to do for you. Such features as our assembly of the unit with push rod cut to proper stroke, special leads, threading and special configurations. Electro-Mechanisms, its sale staff and engineers, are all competent to assist you in the proper selection of a miniature solenoid for your particular application. Let us know your requirement and let us assist you in proper application engineering.