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People usually refer to various types of Bolts and Nuts when they are talking about Industrial Fasteners. The job of a fastener is, as the name suggests – fastening – holding things together mechanically. This is done quite well by dowel pins too. However, while the Bolts and Nuts hold the two components almost “permanently”, by pressing against each other (torque), dowel pins fasten the components non-permanently. They do not use “torque” force to hold components together. They are basically precision pins that are pressed in one component and slipped into another. Thus, by aligning them, it keeps them rotatable and fixed at the same time. They are manufactured in such tight tolerances that the joint completely depends on the “tightness” of the fit. ISO and DIN standards : Dowel Pins are manufactured based on their application and hence, they could be parallel dowel pins such as DIN 7 (ISO 2338) or DIN 6325 (ISO 8734). They could also be tapered on one end, such as DIN 1 (ISO 2339). Other variants may include pins with internal threading such as DIN 7979 (ISO 8735A) which is a parallel pin with internal threading, or DIN 7978A (ISO 8736) which is a taper pin with internal threading.Internally threaded pins are a little more easily “extractable” once they are press fit into a component, with a screw being inserted into the threaded hole and thus enabling it to be “pulled” out. The ends of the tapered or straight dowels can be kept either rounded (D shaped) or a little chamfered (C Shaped). Chamfered pins are generally more locatable before being press fit. Dowels can be manufactured with a slightly smaller diameter than the hole in which it would fit, so that it can be slipped into it. The term used for such diameters and tolerances is “slip fit”. Alternatively, they can be made with a slightly larger diameter than the hole, and hence have to be pressed into the hole to fit tightly. They are called “press fit” dowels. Materials Used and Heat Treatment / Surface Roughness The pins are usually made from alloy steel (free cutting steel), carbon steel and stainless steel (AISI 303, AISI 304 and AISI 316). They could be supplied in soft or hardened condition based on their end application. Hardening can be only “case” hardening or it could be “thorough” hardening. Surface roughness is also a defining criterion in dowel pins and usually given as Ra values. Dowel Pins are generally available in Metric as well as Inch series. Clevis Pins Clevis Pins are generally used in Agricultural industry and they are pins with a round head and a hole at the end of the pin shank. The shank is usually either partially threaded, or not threaded at all. The clevis pins dimensions are defined by standards such as ISO 2341 and DIN 1444. Their round head sits into one end of a clevis (a U shaped or a forked connector) and since the shank is longer than the other end of the clevis, it pops out along with the hole at the end of the shank, where a cotter pin is inserted to secure the position of the pin inside the clevis. Clevis Pins are usually hardened, as they have to undergo quite a lot of wear and tear due to shear force applied on them. The materials used in manufacturing clevis pins are usually alloy steels which are hardened to a suitable core or surface hardness.
Related Articles -
dowel pins, clevis pins, DIN 7, DIN 6325, parallel pins, parallel dowel pins, ISO 8734, ISO 2338, ISO 2341, DIN 1444, DIN 1434, DIN 1435, DIN 1436,
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