Everything You Should Know About Micro Switches

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What Is a Micro Switch?

A micro switch is a rapid-action switch that requires minimal force to operate. It is also referred to as a miniature snap-action switch. Known for its reliability, speed, and efficiency, this component is essential for smart devices. Micro switches serve as safety mechanisms in various applications, such as preventing door closures when obstacles are detected.

A micro switch typically contains three pins: Common (C), Normally Closed (NC), and Normally Open (NO). The Common pin acts as the input, while NC is Output 1, and NO serves as Output 2.

With its compact contact gap, the micro switch is a precision device tailored for logic-level and power-duty loads. Available in SPDT, SPNO, and SPNC options, it facilitates power-duty switching through silver alloy contacts. Various electrical terminations are offered, with logic-level control achievable through silver alloy or gold-plated contacts.

How Does a Micro Switch Work?

The actuator in a micro switch elevates a lever when pressed, repositioning the contacts accordingly. When activated, these switches emit a distinct 'click'. They frequently come with mounting holes for quick installation. Due to their longevity, micro switches require minimal maintenance.

The operation principle is straightforward: depressing the switch lever opens the normally closed pin and closes the normally open pin. Releasing the lever reverts the normally closed pin to its conductive state while isolating the normally open pin.

An intrinsic tipping point mechanism characterizes micro switches, enabling the creation of specific tripping and reset points that alter the state of the contacts.

Micro Switch Circuit

The following circuit diagram illustrates a micro switch controlling two LEDs with a battery. The micro switch comprises three terminals: C, NC, and NO. The switch functions as depicted in the diagram below.

When the lever is pressed, there is no connection between the NO terminal and the Common terminal, causing the green LED to illuminate. Once the lever is released, the connection between the Common terminal and the NC terminal activates the blue LED. The switch can operate in either NO or NC mode based on application requirements.

Construction of a Micro Switch

Constructing a micro switch necessitates various components, including an actuator (plunger), cover, movable piece, support, NC terminal, NO terminal, contacts, and a moving arm.

Plunger

Also referred to as the actuator, the plunger is a mechanical element that manually controls the circuit by toggling its state.

Cover

The cover provides protection against external forces.

Moving Piece

The moving component applies the necessary force to the contacts and is located within the actuator.

Support

This component serves to secure the micro switch in place.

NO Terminal

Normally Open (NO) terminals signify that the switch contacts remain open by default, preventing current flow through the circuit.

NC Terminal

The Normally Closed (NC) terminal is designed such that the contacts remain closed by default, allowing current to flow through the circuit.

Contact

Switch contacts are typically made of conductive material, primarily metal, and serve the fundamental purpose of establishing or breaking electrical continuity.

Moving Arm

The lever mechanism is crucial for the activation and operation of the micro switch.

Different Types of Micro Switches

Micro switches come in various lever terminal types chosen based on specific applications. Some available types include Pin Plungers, Hinge Roller Levers, Rotary Operation, Short Straight Levers, Standard Straight Levers, Long Straight Levers, Extended Straight Levers, Small Simulated Roller Levers, Standard Simulated Roller Levers, Roller Levers, and L-Shaped Levers. Here are some types highlighted below:

Rotating Operation Micro Switch

This type of micro switch is used with low-torque actuators, making it ideal for detecting lightweight objects such as paper currency.

Pin Plunger Micro Switch

Pin plunger micro switches are suitable for direct, short strokes, allowing for the high-precision detection of positions. Given their minimal overtravel, they require consistent stoppers.

Spring Pin Plunger Micro Switch

A spring pin plunger micro switch offers more overtravel than a pin plunger but should be used for similar applications. Ensure load centering on the plunger due to its increased diameter.

Hinge Roller Lever Micro Switch

The hinge roller lever micro switch is characterized by a roller attached to the lever, making it suitable for high-speed camera operations.

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Leaf Spring Micro Switch

This type of micro switch has a greater stroke due to its robust leaf spring. It is suitable for usage with cams or cylinder drives at slow speeds. Protect against damage by ensuring the overtravel switch is used within specified applications, as a leaf spring has a permanent bearing point.

Panel Mount Plunger Micro Switch

This micro switch features the largest overtravel compared to other varieties. It can be panel-mounted using a nut and hex nut, enabling hand or mechanical operation. Additionally, it's compatible with slow-speed cams.

The Differences Between Micro Switch and Limit Switch

How to Maintain a Micro Switch

Proper maintenance of micro switches ensures durability and reliable performance. Here are some essential steps for maintenance:

1. Keep it clean: Micro switches are vulnerable to dust; regular cleaning with a dry cloth is advisable. Avoid chemical cleaning agents, as they might harm the switch.
2. Avoid harsh environments: Micro switches should not be used in explosive or flammable atmospheres, as they could be compromised.
3. Inspect contact parts: Regularly inspect the switch contact areas to ensure smooth operation, confirming that the limit distance is accurate.
4. Monitor voltage and current: Regularly check the circuit's voltage and current since fluctuations can severely impact the switch.
5. Periodic maintenance: Micro switches in automated systems should be evaluated every 2-3 months to check for signs of damage.

Advantages & Disadvantages of Micro Switches

Advantages:

Micro switches are known for their precise performance, reliability, affordability, and low maintenance requirements. They are versatile and resistant to dust and water, with their fast switching significantly reducing arcing damage.

Disadvantages:

Low-quality components may lead to issues, such as component burns, degradation, and unexpected failures.

Micro Switch Applications

Micro switches are widely used in countless devices. They are crucial in timing mechanisms when coupled with other components. Commonly used in home appliances, automobiles, and industrial machines, micro switches also provide control in devices like printers, lamps, and solenoids.

They find applications in vending machines for jam detection and coin insertion, serve as safety devices in elevators, and are essential for detecting open/closed valve positions.

Due to their reliability, micro switches are indispensable in everyday products and industrial machinery alike.

Final Words

If you're sourcing micro switches for your projects, Elecrow stands as a premier electronic component supplier, providing sourcing services for diverse applications.

Besides micro switches, Elecrow deals with various electronic components such as sensors and LEDs. Their user-friendly website streamlines component search, accompanied by prompt shipping worldwide.

For high-quality micro switches or other electronic components, Elecrow is a commendable choice. Their extensive product range and excellent customer support ensure you receive exactly what you need quickly and affordably.

Moreover, if you're a DIY electronics enthusiast keen on realizing your projects, Elecrow offers a Partner Seller Program to assist you in bringing your ideas to life. Through this program, you can manufacture and market your electronic products online.

Participate in Elecrow's Partner Seller Program to start reaping the benefits!

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