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Shoulder Bolts, also known as shoulder screws or shoulder bolts, are bolts with a smooth cylindrical shoulder that is larger in diameter than the threaded portion. They are typically used where bearing surfaces are required or in rotational applications such as machine assembly, mold and fixture manufacturing, etc. Shoulder bolts can provide precise positioning and support and are indispensable fasteners in mechanical equipment.
In the fastener industry, metric (Metric) and American (Imperial) shoulder bolts are two different standards. They differ significantly in size, thread design, material standards, application fields, etc. The following is a detailed description of the differences between these two types of shoulder bolts.
Dimensions
Metric shoulder bolts
Metric bolt sizes are measured in millimeters (mm), and common specifications include M3, M4, M5, M6, M8, M10, etc.
The shoulder diameter and length of metric shoulder bolts are both in millimeters. The shoulder diameter ranges from 3mm to 20mm, and the shoulder length ranges from 5mm to 100mm.
American shoulder bolts
The size of American bolts is measured in inches. Common specifications include #4-40, #6-32, #8-32, 1/4-20, 5/16-18, 3/8-16, etc.
The basic unit of shoulder diameter and length of American shoulder bolts is inches. The shoulder diameter ranges from 1/8 inch to 1 inch, and the shoulder length ranges from 1/4 inch to 4 inches.
Thread design
Metric shoulder bolts
The design standards for metric threads are based on ISO (International Organization for Standardization) standards. Commonly used standards are ISO 68-1, ISO 261 and ISO 262.
The pitch of a metric thread (the distance between two adjacent threads) is expressed in millimeters. For example, M6x1.0 represents a bolt with a diameter of 6mm and a pitch of 1.0mm.
American shoulder bolts
The design standards of American threads are based on ASME (American Society of Mechanical Engineers) standards, and the commonly used standard is ASME B1.1.
The pitch of American threads is expressed in threads per inch (TPI). For example, 1/4-20 means a 1/4 inch diameter with 20 threads per inch.
Material standards
Metric shoulder bolts
The material standards of metric bolts are based on international standards such as ISO and DIN (German Industrial Standards). Commonly used materials include carbon steel, stainless steel, alloy steel, etc.
Common metric shoulder bolt material grades include 8.8, 10.9, 12.9, etc. The numbers indicate the tensile strength and yield strength of the bolt.
American shoulder bolts
The material standards of American-made bolts are based on ASTM (American Society for Testing and Materials) standards. Commonly used materials include carbon steel, stainless steel, alloy steel, etc.
Common American shoulder bolt material grades include Grade 2, Grade 5, Grade 8, etc. The grade indicates the tensile strength and yield strength of the bolt.
Application areas
Metric shoulder bolts
Metric bolts are widely used in Europe, Asia and most parts of the world, especially in machinery manufacturing, automotive industry, electronic equipment and other fields.
Due to their high degree of international standardization, metric bolts are suitable for applications requiring tight tolerances and high precision.
American shoulder bolts
American-made bolts are widely used in North America, especially in construction, aerospace, petrochemical and other fields. They are used in the construction sector for structural connections and assembly, and in the aerospace sector for the fixation of precision instruments and equipment. In addition, they are used in the petrochemical industry for the connection of pipelines and equipment, providing reliable support and positioning to ensure efficient and stable operation.
