Open Frame Solenoids

Demystifying Open Frame Linear DC Solenoids

Comparing and contrasting open frame linear DC solenoids with other types of solenoids

Linear solenoids are an intricate part of our everyday life. They are used in locks, cars, vending machines, and most of the equipment and appliances we use daily.

There are several types of linear solenoids in the market, these include tubular solenoids, latch solenoids, and open frame linear solenoids.

Each is designed to better deliver on the needs and functions of different applications.

Open frame varieties are the least understood of the group and, in most cases, are confused with tubular solenoids, while they are a very different type of product.

Let’s have a closer look at open frame linear DC solenoids, their components, how they work, and how to realize their benefits.

What are Open Frame Linear DC Solenoids?

Open frame solenoids have the most straightforward design among the different types of linear solenoids. They are defined as a solenoid with a mechanically unprotected, visible, over-molded, or taped coil with a movable plunger at the center of the coil.

Because of their unique build, open frames are lightweight and more cost-effective than other types of linear solenoids.

Like most other linear solenoids, open frames generate force in a single direction, which can be a pull or a push when energized.

How are Open Frame Linear Solenoids Different from Tubular Solenoids?

It is best to compare solenoids based on the critical features you should consider when choosing a solenoid. This requires a clear understanding of the differences between the three types of solenoids.


One of the differences is the structure. Only tubular solenoids have an enclosed design with the coil safely tucked away inside a metal casing. Open frames have the coil exposed on at least two sides. Magnetic latch solenoids can have the tubular or open frame design.

The general shape of both the latch and open frames is generally the same. Across the variations within these solenoid categories the shape and dimensions between the two can vary slightly.


All tubular, open frame, and magnetic latch solenoids come in push and pull varieties. In both tubular and open frames, the center plunger is movable without current and has a flexible duty cycle that can be continuous or intermittent depending on the requirements of the applications. In latch solenoids, the plunger is held in place by a permanent magnet, with no chance of a continuous cycle.

Stroke and holding force

Latch and open frame solenoids have very similar statistics in terms of holding force and stroke length. However, unlike open frames, magnetic latch solenoids do not require current in the end position.

Life expectancy

Open frame solenoids are typically benchmarked at 50 to 100 thousand cycles, while tubular varieties are more durable with a life expectancy of above 25 million cycles.

The above comparisons are meant to highlight the differences in how the various options will be optimized for the best performance given the operating environment and application.

Applications of Open Frame Linear Solenoids

Open frame solenoids have a vast range of applications in across different industries. Some of the most common applications include:

  • Vending machines
  • Residential and commercial locks
  • Card key locks (smart locks)
  • ATM machines
  • Battery operated locks
  • Cash drawer machines
  • Medical supply cabinets
  • Gaming machines

Matching the right part to the proper application is critical in ensuring the best performance and operation. At Johnson Electric, we have an expansive line of open frame linear DC solenoids in different sizes, force, and stroke options to best fit your applications. Contact us today and let us help you find the solenoid solution for your needs.

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