A dowel is essentially a cylindrical alloy rod that is primarily used to connect parts in large machinery that require precise overlap. In order for these components to perform their tasks efficiently, their structure and strength are critical. This is why the American Society of Mechanical Engineers standardizes the manufacturing specifications for dowel pins as follows:
Accepted Material
Typically, dowel pins are made of steel alloys that contain small amounts of sulfur and phosphorus, more precisely 0.04% and 0.05%. However, because pins are used in multiple industries—including water treatment, pump manufacturing, steel manufacturing, and railroad construction—they can also be used in other materials, such as bras, 18-8 and 316 stainless steel, aluminum, and titanium.
Design
Regardless of the metal alloy used, the pin undergoes a hardening process called austenitization. This procedure is often used for iron-based metals, meaning that they are exposed to excessively high temperatures, which change the crystal structure to austenitic (gamma-iron).
Hardness Factor
The function of the austenitizing process is to achieve a certain hardness inside and outside of the positioning pin. In short, according to ASME standards, a dowel pin is properly manufactured if it has a case hardness of at least 60 and a core hardness between 47 and 58. Hardness is usually measured on the Rockwell C scale, a system used to calculate the indentation of steel using a pointed diamond cone. Naturally, harder steel alloys have fewer indentations than softer alloys.
Crown End Specification
The crowned or rounded ends of dowels are obtained through a process called filleting, which involves removing sharp edges and flattening their overall surface to make them easier to work with. Here the manufacturer needs to ensure that the height and radius of the crown are in accordance with ASME specifications. For example, a 1/8" dowel must have a crown height of 0.041" and crown radius of 0.016".
Chamfer End Measurement
The angle of the chamfered or beveled end of the dowel must be between 4 and 16 degrees to be considered suitable for use. The angle of inclination is usually specified by the minimum and maximum point diameters. Remember, because dowels come in a variety of sizes, from 1/8'' to 1",
You should pay attention to these data when shopping around for dowel pins, as the final hole diameter and pin must match exactly. If the pins are too small, they will slip out of the holes, and larger ones won't fit at all.
