Magnet-Schultz of America Blog

Developing a Preliminary Specification for Solenoids and Electromagnetic Devices

Posted by: David Stockwell, Magnet-Schultz of America, CEO

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Tue, May 05, 2015 @ 02:17 PM

Specification guidelines for solenoids and electromagnetic devices

Developing a Preliminary Specification for Solenoids and Electromagnetic Devices

When System Design Engineers are tasked with incorporating an electromagnetic device (i.e. a solenoid, electromagnet, voice coil, etc.) into a new product, it would be useful if they could readily access design “guidelines” that would help them to identify, quantify and then communicate the performance characteristics needed to meet their system’s dimensional and performance requirements.

Great idea, but, where does one find this list of guidelines?

Below, is a list of 19 questions, the answers to which will provide an outline of a system’s overall requirements, which can then become the basis for the development of a suitable electromagnetic actuator specification.

Admittedly, such a long list may seem a bit daunting. And, to be sure, this is not the sum total of everything that will eventually need to be understood before the design is finalized. However, providing answers to as many of these questions as possible is the best way to “kick-start” the development process, and take the first step toward bringing your system to market more quickly.

Technical Questions

  1. Describe your Application
    Describe the application (the purpose your system will serve).

  2. Function of the device
    Explain exactly what function the electromagnetic device is intended to provide.

  3. Define the potential risk involved in operating your system with the new device
    If you are not familiar how “risk” is defined in this context, start by answering the following
    1. Is my application Safety Critical?
      In other words; What are the ramifications (i.e. the potential for injury to property and/or individuals) if the electromagnetic device you choose fails to operate your within system as desired?
    2. FMEA (Failure Mode and Effects Analysis):
      Do you already have an FMEA which describes the potential failure mode(s) of your system? Does this FMEA include the electromagnetic device?

      If the FMEA concept is new to you, but, you still think that the potential risks involving the
      operation of your system might be worth exploring more deeply, please feel free to read our BLOG titled “FMEA Basics”.
  4. Type of Electromagnetic Device Needed
    1. If your application requires Linear Motion/Actuation:
      Will you need a pull, a push, or a push-and-pull function from the linear actuator?
      Proceed to question 5).
    2. If your application does not require Linear Motion, please jump to question 7) b.
  5. What mechanism will you use to return the linear actuator to the deactivated position?
    1. Will your system have a return spring, or mechanism?
    2. Will the actuator need its own return spring?
    3. Will gravity provide the return mechanism?
  6. Stroke
    How much linear movement (stroke) will be required of a linear actuator to make your system function?

  7. Force
    1. For systems involving Linear Motion:
      1. How much PULL-Force will your system require at the stroke you defined in question 6)?
      2. How much HOLD-Force will your system require to keep the linear actuator in the fully actuated position?
      3. Presuming that neither PULL or HOLD Force are relevant, but you are more concerned with the IMPACT-Force that the actuator can impart to your system, please estimate what you think that IMPACT-Force must be.Presuming that neither PULL or HOLD Force are relevant, but you are more concerned with the IMPACT-Force that the actuator can impart to your system, please estimate what you think that IMPACT-Force must be.
    2. If no Linear Motion is required (suggesting you might need an electromagnet)
      How much magnetic HOLD-Force is required upon energizing the electromagnet?
  8. Speed of operation
    For systems involving linear motion, if operating speed is critical, how quickly (in ms) must the device respond/move upon actuation?

  9. Size
    In what envelope must the device fit within your application?

  10. Power
    1. What input/operating voltage is relevant (i.e. 12VDC, 110VDC, 110VAC, etc.)?
    2. What power source will you use (i.e. a power supply, line voltage, battery, other)?
    3. Is an Energy Saving approach desirable:
      If you are using a battery, or just want to save energy for whatever reason, we can explore
      a magnetic latching device that incorporates a Permanent-Magnet into the electromagnetic
      device. The Permanent-Magnet enables such devices to remain in the actuated position,
      without the need to continuously apply power.

      Is such a feature of interest to you?

      To learn more about the theory of operation and the advantages of Magnetic Latching
      Devices, please feel free to read two other Blogs on this web site titled:

      Permanent-Magnet/Electromagnetic Linear Actuators” and “Magnetic Latching Mechanisms”.
  11. Environmental Considerations
    1. What is the ambient temperature within which your system operates?
    2. What special Water and/or Dust ingression protection is required? Are typical Standards such as IP67, IP69 relevant, or do you have your own set of conditions which must be met?
    3. What special corrosion protection challenges befall your system?
    4. Do you require Hazardous Location and/or Explosion proof certifications?
  12. Duty Cycle
    Under normal circumstances, for what period of time will power need to be applied to the
    electromagnetic device to properly operate your system? This is one factor that defines the
    Duty Cycle of the device, which then determines the coil design.
    1. Continuously (100 % Duty Cycle, meaning, 100% on-time)
    2. Intermittently (25% Duty Cycle, meaning, 25% on-time and 75% off-time, measured in milliseconds).
    3. Pulse (10% Duty cycle, meaning, 10% on-time and 90% off-time, measured in milliseconds).
  13. Durability
    1. Life Cycles
      What is the minimum number of actuations the device must be able to provide over the life
      of your product?
    2. Shock and Vibration
      What unique levels of shock and/or vibration must the device withstand?
  14. Approval Agency Requirements
    What approval agency certifications (i.e. UL, FM, CSA, CE) will be required for your system, and possibly, for the electromagnetic device?

  15. Commercial Questions
    The answers to these questions are as important as the answers to the Technical questions, if you hope to attract serious attention from potential suppliers.

  16. Samples
    1. How many samples are required to complete system development?
    2. What is the need date for these samples?
  17. Annual Quantity
    What is the annual quantity?

  18. Production Start Date
    What is the production start date?

  19. Target Price
    What is the target price for the electromagnetic device needed to make the project viable?

We hope you found this information to be useful, and welcome you to contact MSA to develop an electromagnetic device for your next project.

As a leading manufacturer of standard, specialty and custom Electromagnetic devices—Electromechanical and Electrohydraulic—MSA’s advanced engineering, innovative design and lean manufacturing capabilities enable our customer’s products to outperform their competition. Learn how we can help you with your next project.

Contact MSA Today

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