Machine Pins and Their Types

Machine pins, also known as pin fasteners, fastening pins, or simply pins, are a type of specialty fasteners used to align and join two components together. Pins are available in semi-permanent and quick-release models. Semi-permanent pins may require additional pressure or tools for installation and removal, while quick release pins will typically feature a spring-loaded mechanism which locks them into place to allow for easy installation and removal. Additionally, pins come in a broad range of sizes and materials with different designs to suit a wide array of applications.

The ideal type of machine pin largely depends on the requirement of the applications. The most commonly used machine pin types include cotter pins, dowel pins, hitch & lynch pins, locating pins, and spring pins. In this blog, we will discuss each type and its unique characteristics.

Cotter pins, also known as wire clips or cotter keys, are two-toned wire fasteners used in machine assembly applications to help secure parts or other fasteners in place and prevent their loosening over time. In a quick-release, semi-circular, or circular design, these fasteners generally require a pre-drilled hole or wrap around a shaft component during installation. The most common type of cotter pins, split cotter pins, have rounded heads and flexible prongs. These features make them suitable for insertion into pre-drilled components, as well as for locking other fasteners. Other types of cotter pins are bowtie pins, clinch pins, hairpin cotters, ring cotters, and twist pins.

Another type of machine pin, dowel pins, are straight, short, cylindrical rods used to help align machine components like screws and bolts before they are fastened together. Dowel pins are available in high-precision tapered, slotted, spiraled, stepped, and grooved designs. They also typically have high coefficients of friction, allowing them to fix assemblies in place. The most common applications of dowel pins are in furniture assembly or as simple hinges or axles.

Hitch & lynch pins are similar in both form and function. They are both quick-release, cylindrical, and straight pins used by inserting them into pre-drilled mating holes to temporarily fix or join components together. The main differences between these pins are in their locking mechanisms; hitch pins require an additional fastening component to lock into place, while lynch pins have an integrated locking mechanism. Examples of hitch & lynch pins include clevis pins, detent pins, snapper pins, and toggle pins.

Locating pins are a type of machine pin used to position, align, and fix two workpieces together to tight tolerances. They are available in a broad range of designs and characteristics, such as head and shank style, as well as manual, pneumatic, hydraulic, and electrical activation. Locating pins are cylindrical pins and are suited to a broad scope of applications. Subtypes of locating pins include bullet-nose pins, clamping pins, cone locator pins, drift pins, L-pins, and T-pins.

Finally, spring pins are a type of dowel pin that feature a headless, hollow, cylindrical design available in both coiled and rolled models. As their name suggests, spring pins are made from a metal, usually steel, coiled into a cylindrical spring shape. Spring pins are cost effective, require virtually no preparation before use, and can be used in many scenarios ranging from electrical connectors to metal fabrication applications.

For pins of all types and many other fasteners, look no further than ASAP Fasteners. Owned and operated by ASAP Semiconductor, we can help you find all types of parts for the aerospace, civil aviation, defense, electronics, industrial, and IT hardware markets. Our account managers are always available and ready to help you find all the parts and equipment you need, 24/7-365. For a quick and competitive quote, email us at or call us at 1-714-705-4780. Let us show you why we consider ourselves the future of purchasing.


November 5, 2020

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