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Types of Latches

You come into contact with various types of latches on a daily basis as they're utilized almost everywhere, from magnets that hold that kitchen cabinet door closed to latches used in the automotive industry.

What exactly are latches, and what different types of latches are there? This guide will discuss the different types of latches and offer brief explanations on how they work. We've also included several different applications of latches and what to look for if you ever need to purchase some.

In this article we will take a closer look at:

1. What are Latches?
2. Types of Latches
3. What are the Different Applications?
4. Summary

What Are Latches?

Latches are mechanical, and in some cases, electro-mechanical components that allow the temporary joining of parts that are moving relative to each other, and when actuated, they allow the parts to separate. You have probably seen them on doors and enclosure openings, though they're often used in other devices, such as seat belts and clamps.

In simple terms, latches are fasteners that keep doors, panels and other surfaces closed. However, not all latches are made equal, and their design mostly depends on the application, various methods of actuation, holding and locking style, and mounting methods.

Types of Latches

The difference in the type of latches varies substantially depending on their complexity and application purpose. Engineers, technicians, and end-users should carefully evaluate different types of latches when analyzing the requirements of their designs. There are several different latch types capable of meeting the requirements of various designs and applications. Here are the most common types of latches:

Cam Latches

Cam latches are simple and cost-effective mechanical devices consisting of a body that's typically attached to the cabinet door and a cam lever attached to a door opening. The mechanism is actuated by a quarter-turn motion, which rotates the cam behind the door frame, and secures the door.

They're mostly used to keep enclosures and cabinets closed, though you can further restrict access to unauthorized personnel by opting for a cam-lock — a simple quarter-turn latch with a locking mechanism.

‚ÄčCompression Latches

A compression latch is essentially a cam latch, in one of its many forms, that consists of both the base and the cam lever. However, the notable difference is that they're designed to compress the gasket against the doors and panels openings they secure, thus providing a tight seal.

Compression latches are fantastic for application in specific environmental requirements. The compression of the gasket offers protection against moisture, rain, water, dust, and even vibration. Just like standard cam latches, these are also operated by T-handles or locks.

There are two distinct types of compression latches: fixed and adjustable compression latches. The former provides consistent compression over time, while the latter allows you to gradually alter the compression and decompression.

Slam Latches

A slam latch is a spring-loaded latch whose design involves an enclosed spring mechanism with a slide bolt pushed by the spring and a separate component with a notch or a curve. Either the pin or the notch is curved, which allows the pin to slide in only one direction.

When the door is pushed, the pin glides over the notch, and the spring pushes it out under an angle that prevents it from retracting, thus securing the door. They're usually operated via a knob, a door handle, or some kind of lever that recoils the spring, allowing the door to be opened.

Additionally, they come in a variety of sizes, from small cabinet latches to heavy-duty latches used on cold storage doors. You can incorporate a key lock into the latch for additional security.

Draw Latches

Draw latches, also known as toggle latches, rely on tension to securely join two surfaces in the same plane. Typically, this latch style is made up of two sections; the first is the operating mechanism attached to one of the surfaces, and the other is a securing mechanism attached to the other surface. When the lever of the operating mechanism is hooked onto the securing mechanism, tension is created.

These are mostly used on engine hoods, HVAC equipment, and toolboxes, as they're simple and cost-effective to use and provide an ample amount of compression, enough to reduce any minor vibrations.

Sliding Latches

Sliding latches, also known as bolt latches, are your standard back gate latches consisting of a stationary keeper and a sliding and rotating bolt. The two parts are mounted on securing surfaces, such as doors and frames, which become secure when the sliding or rotating bolt moves behind the stable piece.

Actuation is typically performed by hand; they're pretty straightforward to install and use and don't really offer much in terms of security, which is well-reflected in their price point. However, it's worth pointing out that there are sliding latches equipped with a spring for automatic bolt extension.

Hasps

A hasp is a simple and easy-to-install and operate latch consisting of a strap, and a staple, which rely on padlocks for added security. The strap is a metal plate with a slot that fits over the staple on one end, while the other end features a hinge that allows the strap to swing while being attached to a surface.

The other component, referred to as a staple, is a loop produced from a bent metal rod or formed plate. To fasten the strap, a pin is put into the loop of the staple, or a padlock is used if the application demands additional security.

Magnetic Door Latches

Magnetic door latches, also known as door catches, are two-part devices consisting of a permanent magnet and a ferromagnetic strike plate. They're used to provide a convenient latching of furniture doors or light-duty and low-traffic doors. However, you can opt for an electromagnetic door latch if you need added security.

Electromagnetic latches work on a similar principle but require a power supply to operate. When the magnet becomes energized, it bonds to the frame and locks the door. To provide access, you must first de-energize the magnet via a switch.

What Are the Different Applications?

All latches serve the same purpose: to keep the doors, enclosures, and other surfaces closed. The type of latches used mostly depends on their application, set under specific industry standards. For example, electrical enclosures require that all levers used for the actuation of latches must be made of non-conductive material.

Considering that the choice of latches is based on the applications within specific industries, we'll categorize them into indoor and outdoor applications.

Indoor Latches

Indoor applications don't usually have strict requirements as outdoor applications since you don't have to worry about environmental impacts and elements. You can opt for latches made of more affordable plastics or zinc to keep the overall price within the budget.

Additionally, indoor applications may also require a lower level of security than outdoor applications. Depending on the access control requirements within the interior environment, you can opt for non-locking latches. However, if you want to keep unauthorized personnel out, consider alternatives equipped with a locking mechanism.

Outdoor Latches

Compared to indoor latches, outdoor latches usually have much stricter criteria and standards to adhere to. You'll have to account for all the environmental factors, including the elements like extreme humidity, ice, and meteorological events.

This can play a crucial role in determining which type of latch you need, considering that stainless steel latches are corrosion resistant and won't suffer any degradation when exposed to elements.

Depending on the industry, there may also be water and dust infiltration compliance laws and standards that must be met. Latches used in electrical and food equipment, for example, may need to meet certain design, construction, or sealing criteria, such as IP, NEMA, or UL specifications.

By ensuring that water and dust do not interrupt mechanical or electrical systems, latches that satisfy these criteria can improve overall equipment performance. However, water and dust aren't the only things that can potentially gain access to the contents of your enclosure.

Mounting an enclosure outside often carries certain security risks, depending on its location and contents. For example, a utility company should install a latch that permits only authorized technicians to access the panel inside a remote electrical box.

Outdoor latches are typically made of tougher materials and feature greater durability, as they're often subject to damage and vandalism. For this reason, they're often equipped with more complex and sophisticated locking mechanisms for increased security.

Design Features and Specs

Latches can have a variety of design elements that make them better suited for specific purposes. In addition, they're available in a variety of materials, coatings, thicknesses, and other characteristics.

Material

Most latches are primarily made of metal, such as carbon and stainless steel, alloy steels, aluminum alloys, and copper alloys. Metal is the most prominent material due to its durability and strength. The external characteristics of metal latches can be improved further by secondary processes, such as finishing and coating.

Metal latches are often coated with plastics and rubber trim, which provides shock absorption, and reduces vibration. In addition, however, there are plastic-made latches. Unfortunately, plastics become very brittle due to prolonged exposure to the sun and the elements, which is why they're only used as indoor latches.

Finishing and Coating

Finishing and coating are secondary processes that are used to improve the surface quality of latches and other items. These include painting, polishing, powder coating, and metal-plating.

·        Polishing and buffing — Polishing and buffing create a smooth surface and a bright finish. These processes remove microscopic burrs and scratches from a surface, which provides marginal stain resistance.

·        Painting and powder coating — These processes add a layer of polymer material to the surface of the part to prevent it from corroding. The coating can come in a variety of colors that enhance the product's appearance and add corrosion resistance to the metal latch.

·        Metal-plating — This process applies a thin layer of metal, such as zinc, silver, and chromium, to a base metal used in the latch's construction. The metal is deposited onto the part's surface using electrochemical deposition, resulting in stronger corrosion resistance, making it suitable for outdoor use.

Strength

When it comes to strength, latches can be light, medium, and heavy-duty, which dictates the thickness of sheet metal or metal plates used to make a backplate, battels, and rotors. Of course, the same applies to cams and bolts — their thickness also varies, depending on the application.

Mounting

When it comes to installing latches, there's a wide variety of mounting options to choose from, like flush-mounted, mortised, or surface-mounted latches. A flush-mount latch has both the door and the latch on the same surface level. Paddle latches are the most common example of flush-mount latches.

Mortise latch is your typical door lock that contains a deadbolt for locking purposes and only has a handle and a keyhole protruding on the door's surface. Lastly, surface-mounted latches are simply installed by bolting the latch assembly onto the door and frame's surface, without any drilling necessary (though some pre-drilling would help).

Latch Handedness

Though most of them are universally operated, some latches come in left-handed and right-handed varieties to allow easier operation. In addition, slide latches and certain designs of bolt, rotary, and slam latches allow swapping out the mechanism for left- or right-handed operation.

Unfortunately, this characteristic isn't featured on all designs, and neither of those alternatives is available. This leaves you with determining the handedness of the latch by looking at the position of the hinges.

Summary

Latches are mechanical components that allow parts to move relative to each other to be temporarily joined. They are triggered to separate the two components by releasing the coupling that holds them together. The sheer number of latch types is too vast to count, so make sure to evaluate your design carefully.

It's important to consider the right product made of high-quality material for your application, so it's imperative to find a reliable and trusted supplier. If you're interested in learning more about latches, or you're in the market for some, visit us at Reid Supply. Besides offering different types of latches in our online store, we also offer e-handbooks, guides, and product and partner information.