Among pin-type fasteners, several similar products share comparable appearances and application scenarios. Here we will detail the distinctions between cylindrical pins and taper pins.
First, let's look at cylindrical pins, which comply with the national standard GB/T 119. Classification of cylindrical pins is based solely on their structural shape rather than material; they feature a uniform cylindrical shape with the same diameter throughout the entire length. They can be manufactured from either stainless steel or carbon steel, with the material selected according to actual application requirements. Though seemingly simple in structure, cylindrical pins have stringent manufacturing precision requirements. Their length tolerance must be controlled within ±0.02 millimeters, and positive tolerance is generally not adopted in actual production, leaving a strict negative tolerance of only 0.02 millimeters. The diameter tolerance requirements are even higher: cylindrical pins are available in two tolerance specifications, negative and positive. Cylindrical pins with negative tolerance require the diameter deviation to be within -0.02 millimeters, while those with positive tolerance demand a deviation within +0.01 millimeters. Such high-precision requirements cannot be achieved through direct primary processing, so cylindrical pins must undergo centerless grinding to meet the standard specifications.
In some operating environments, cylindrical pins are required to meet specific strength and wear resistance standards. For such scenarios, they are manufactured from 45# steel and undergo surface carburizing treatment after forming to enhance surface hardness and wear resistance. The product most similar to the standard cylindrical pin is the cylindrical pin with internal threads, which features an internal thread machined at one end of the standard cylindrical pin. Below we compare the standard technical drawings of these two similar products.
Of the two standard cylindrical pin products mentioned above, the one on the left is of the specification 8×35, where 8 refers to a diameter of 8 millimeters and 35 denotes a length of 35 millimeters (all units in millimeters). For easy comparison, the cylindrical pin with internal threads on the right also has a diameter of 8 millimeters, with the specification 8×60 (8mm in diameter and 60mm in length). The only difference is that this cylindrical pin with internal threads is machined with an M5 internal thread at its tail, with a thread depth of 8 millimeters-this is the standard design of cylindrical pins with internal threads.
Next, we turn to taper pins, which are specified in the national standard GB/T 117. The core difference from cylindrical pins is evident in the term "taper" in their name. Taper pins adopt a structural design with a larger end and a smaller end, featuring a standard taper throughout the entire pin. Their production process is relatively more complex than that of cylindrical pins: cylindrical pins, with a uniform diameter, can be formed simply through bar cutting and subsequent precision machining. In contrast, taper pins, with different diameters at the two ends, require turning to machine the standard taper after bar cutting, followed by precision machining to form the final product. The product most similar to the standard taper pin is the taper pin with internal threads, which is machined with an internal thread at one end-applying the same design concept as the cylindrical pin with internal threads. Below we refer to its technical drawing.
The taper pin on the left is of the specification 10×60, where 10 millimeters refers to the diameter at the larger end. In accordance with the 1:50 standard taper ratio specified in GB/T 117, the diameter at the smaller end of this taper pin is 8.8 millimeters, forming the standard taper. The taper pin with internal threads on the right is of the specification 10×50, and its biggest difference from the standard taper pin is an M6 internal thread machined at the larger end.
These are the most commonly used and similar pin-type fasteners on the market. For any requirements of special-specification pin-type products, please feel free to contact us directly.
