Jiangxin Time: What is the difference between metric shoulders and American shoulders?

Introduction to Shoulder Bolts

Shoulder Bolts, also known as Shoulder screws or shoulder bolts, are bolts with a smooth cylindrical shoulder whose diameter is larger than the threaded part. 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.

The difference between metric Shoulder bolts and American Shoulder bolts

In the fastener industry, metric (Metric) and American (Imperial) Shoulder bolts are two standards with different specifications. They differ significantly in size, thread design, material standards, application areas, etc. The following is a detailed description of the differences between these two Shoulder bolts.

Size Specifications

Metric Shoulder Bolts

The size of metric bolts is 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, with the shoulder diameter ranging from 3mm to 20mm and the shoulder length ranging from 5mm to 100mm.

American Shoulder Bolts

The size of American bolts is in inches, and common specifications include #4-40, #6-32, #8-32, 1/4-20, 5/16-18, 3/8-16, etc.

The shoulder diameter and length of American shoulder bolts are both in inches, with the shoulder diameter ranging from 1/8 inch to 1 inch and the shoulder length ranging 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, and the 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 for American threads are based on ASME (American Society of Mechanical Engineers) standards, and the commonly used standard is ASME B1.1.

The pitch of an American thread is expressed in threads per inch (TPI). For example, 1/4-20 represents a diameter of 1/4 inch and 20 threads per inch.

Material standards

Metric Shoulder bolts

The material standards for metric bolts are based on international standards such as ISO and DIN (German Industrial Standards). Common materials include carbon steel, stainless steel, alloy steel, etc.

Common metric Shoulder bolt material grades include 8.8, 10.9, 12.9, etc., and the numbers indicate the tensile strength and yield strength of the bolts.

American Shoulder bolts

The material standards for American bolts are based on ASTM (American Society for Testing and Materials) standards. Common materials include carbon steel, stainless steel, alloy steel, etc.

Common American Shoulder bolt material grades include Grade 2, Grade 5, Grade 8, etc., and the grades indicate the tensile strength and yield strength of the bolts.

Application areas

Metric Shoulder Bolts

Metric bolts are widely used in Europe, Asia and most parts of the world, especially in the fields of machinery manufacturing, automotive industry, electronic equipment, etc.

Metric bolts are suitable for applications that require strict tolerances and high precision due to their high degree of international standardization.

American Shoulder Bolts

American bolts are widely used mainly in North America, especially in the fields of construction, aerospace, petrochemicals, etc. They are used for structural connection and assembly in the construction field, and for fixing precision instruments and equipment in the aerospace field. 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.