Several different pin fasteners serve various purposes across almost every conceivable industry, though they're mostly used in machine engineering and manufacturing. Today's article will discuss detent pins — fastening solutions that allow for quicker installation and removal, enabling more rapid operations during frequent adjustment.
Detent pins, also known as quick-release pins, are used in applications that require rapid, frequent, and manual assembly and disassembly of a specific product or object. One end of the pin features a ball bearing, or perhaps two, with the actuation mechanism that springs the balls out to secure the pin in place.
Most ball detent pins feature only one spring-loaded ball that's actuated by pulling force. Instead of a push-button mechanism, ball-lock pins feature pull-rings that help users grip the detent pin and remove it with a sharp tug. There are several different detent pin designs, but most of them are simple headless dowel pins of a hollow cylindrical design.
In most cases, quick-release detent pins are made of 316 stainless steel materials, making them suitable for use in different industries. The 316 stainless steel has fantastic anti-corrosion properties, which primarily makes detent pins made of this material suitable for use in medical, chemical, and food processing industries.
However, extreme heavy-duty applications demand high-carbon steel pins due to their exceptional resistance to shearing forces. High-carbon steel is very susceptible to staining and corrosion, even in contact with air, so in most cases, zinc-plated steel is used to prevent metal deterioration.
Lastly, certain applications demand the use of non-sparking tools, such as in nylon stocking production facilities, in which a single, accidental spark could cause a massive fire within seconds. Brass doesn't spark unlike ferrous metals, such as steel, which will generate spark upon impact. It also tolerates extremely low temperatures. Brass hitch pins are perfect for non-spark applications, but there's a trade-off in terms of shear strength.
Several different types of detent pins are available on the market, and selecting the right type greatly depends on your application.
Pull-ring detent pins, also known as cotterless hitch pins, are a slight upgrade over typical pull-dowel pins, as they're basically self-locking and don't require a cotter pin to secure them in place. These are made in various sizes and of different materials to satisfy different applications. In frequent-use applications, these fasteners are usually secured to a piece of equipment using lanyards, pinchains, or key retractor tools.
Ball-knob detent pins are basically the same as pull-ring and cotterless hitch pins, but instead of a handle, or a pull ring, they have a ball knob handle, which allows for an easier grip. In some instances, it would even allow you a greater pulling force necessary to actuate the ball and remove the pin from the pin receptacle.
Just like regular clevis pins, detent clevis pins have a domed head at one end. However, instead of a cross-bore on the other end, detent clevis pins have a spring-loaded ball that secures the fastener instead of a typical cotter pin. This makes operation much more straightforward, as it removes the unnecessary steps involved in removing a cotter pin to unfasten the clevis fastener.
Ball-lock pins feature two-spring loaded balls at the end of their effective length, whose release is actuated via a push-button, usually located at the top of the T-handle. They're most widely utilized in the automation and robotics industries and machine manufacturing because their positive locking mechanism ensures solid component fastening.
Spring plungers are small and narrow pins, usually with an external thread that's used to secure them in prefabricated threaded bores. They're mostly used for indexing and positioning various components. These devices use a spring to apply the pressure to the ball, which remains positioned at all times, regardless of how much pressure is exerted upon it.
Threaded detent pins are quick-release alignment pins with solid shank and spring-loaded locking balls. These pins have one end threaded to fit a knob handle, the purpose of which allows easier handle removal and installation in special applications.
There are basically two types of detent pins: spring-loaded and positive locking pins, the latter of which actually require a push-button actuation to release the pin.
Spring-loaded pins are made by drilling a perpendicular hole into a pin at a specified depth and diameter. Then, a spring is inserted, followed by a steel ball — placed into position on top of the spring. Afterward, a "punch" tool compresses the ball and the spring into the pin while deforming the material to make the top of the hole slightly narrower, thus "capturing" the ball inside the pin.
Positive locking pins feature a complex internal mechanism that uses spying-actuation to allow the ball to retract and protrude from the pin itself. The manufacturing process alone is much more complex compared to spring-loaded pins, as it involves more machining operations necessary for creating an adequate assembly.
Spring-loaded ball pins operate via a simple push-pull operation, needed to install and remove the pin. The pulling and pushing force exerted on the pin has to be greater than the force with which the internal spring pushes the ball outwards.
Quick-release positive locking pins actually have a hollow shaft featuring an internal spring-loaded spindle with a narrow section. Upon actuation, usually by pressing a push-button, the spindle moves forward, and the narrow section creates space, allowing the balls to retract into the shaft. However, upon releasing the push-button, the spindle moves backward, and its expanding section pushes the balls outwards, preventing their retraction into the pin.
Detent pins have been utilized in various industries to secure parts relative to each other, allowing for quick and straightforward adjustment of various types of machinery. If you're in the market for detent pins, visit Reid Supply, a prominent industrial component supplier with a broad assortment of locking and self-locking fasteners of both threaded and unthreaded variety.