Heat treatment: Steel pins can be hardened by a process of heating and cooling, which changes their metallurgical properties.įinishing: Finishing adds a coating to the pin’s surface. Rolling: Spring pins are manufactured by rolling metal strips into a tube or coil. This process is essential for pins that will be pressed into place, where precise diameters are essential.ĭrilling: Pins may be drilled to create holes for other fasteners, clips, or detents. Grinding: Pins may be ground to add features such as chamfers or to achieve exact specifications with tight tolerances. Turning is used to shape, groove, bore, and part pins. The lathe spins the part at high speeds, and a cutting tool removes material. Turning: Larger diameter pins are turned on a lathe. Learn more about wire forming and wire forming machines. ![]() Wire forming: The wire is shaped on a wire forming machine, undergoing processes that include bending, stamping, and upsetting. ![]() Manufacturing processes include:Ĭutting: The rod or wire is cut to the desired size. They undergo different processes depending on the type of pin. Metal fastener pins are formed from metal rods, wires, or sheets. Detents are found in detent pins and cotterless clevis pins. The detent sits against a spring so it can be compressed during installation and removal. Examples include bridge pins, lynch pins, and cotter pins.ĭetents: A detent is a mechanism with a ball or latch that protrudes from the pin’s surface. Spring force: The pins are designed to compress, exerting a spring force against the sides of the hole examples include slotted spring pins and coiled spring pins.Ĭlips and pins: Retaining clips and pins are inserted through a hole in a larger pin so it can’t pull out. Press fit fasteners are also known as interference fits or friction fits. Press fits can generate significant holding forces that prevent pins from moving axially, although the axial holding forces are less than an equivalently sized bolt. As the pin is installed, it or the hole deforms slightly, causing both components to exert a radial force that holds the pin in place. Press fit: The pin’s diameter is slightly larger than the hole. The pin can fall out of or through the hole, so slip fits are not used in through-hole applications unless the pin is retained in another way. Slip fit: There is little to no friction between the pin and the hole as the hole’s diameter is larger than the pin’s diameter. One of the key differences between fastening pin designs is how they are retained. However, a threaded fastener such as a bolt is better suited for applications with significant axial forces.īecause pins are used in non-threaded holes, they often require friction or tension to keep them in place. Pins secured by a retaining mechanism – cotter pins or hitch pin clips, for example – can be used in scenarios with some axial force caused by rotation or vibration. Pins are less suited to applications where they are primarily exposed to axial forces that would pull or push the pin or connected parts in a direction parallel to the pin’s axis. Pin fasteners are primarily used to secure or connect parts in scenarios in which the main forces acting on them are shear forces – opposing forces which push one section of the pin in one direction and another section in the opposite direction. Today, they are as common and as widely used as threaded fasteners. Pin fasteners pre-date threaded fasteners like screws and bolts by many centuries as the technology to efficiently create screw threads developed much later. ![]() Not correct, at least according to my auto mechanics instructor of many years ago.Pin fasteners, or fastening pins, are non-threaded fasteners used to align and connect components in industrial machines, vehicles, electronics, architecture, and many other applications. Often the pin is installed rotated 90 degrees from the photo so the head doesn’t settle into the notch in the nut and the pin legs are bent perpendicular to the axis of the axle. The ends of the legs are then trimmed, particularly the outside leg, about even with outside edge of the bolt – or axle in this case. One leg of the pin is bent back against the flat of the nut, the other is bent up around the end of the axle and pressed tight against the axle end. In this example, note the head of the cotter pin is set parallel to the length of the axle and is actually set down into one of the notches of the castle nut. This has stuck with me for all these years and I’ve used this technique without fail ever since (even though I’m not an auto mechanic). The instructor was very deliberate in ensuring all the students understood how to properly install a cotter pin when used with a castle nut. I remember exactly where I learned this little tip, from auto mechanics school many years ago.
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