The Importance Of Bolt Specification Representation Method

The representation method of bolt specifications is essential for us to understand when identifying and selecting bolts. Only by understanding the representation method of bolt specifications can we determine the corresponding specifications and dimensions. This article will introduce the representation method and examples of bolt specifications for everyone.

1、 Bolt specification representation method

The representation method for bolt specifications mainly consists of thread feature codes, size codes, tolerance zone codes, thread length, and thread direction codes. The complete thread marking should include the above five items.

1. Characteristic code of thread

The feature code of a thread is represented by the letter "M", indicating whether the thread is metric or metric. For example, the thread specification is represented as "M14", which means that the thread is a metric thread with a major diameter of 14 millimeters.

2. Size code

The size code refers to the diameter, pitch, and torque of the thread. The size code for single thread is "nominal diameter × Screw moment ", such as" M16 × 2 ". For coarse thread, the screw moment term can be omitted. The size code for multi thread threads is "nominal diameter × Ph lead P screw torque ", such as" M12x1.75 × 8 ".

3. Tolerance zone code

The tolerance zone code consists of numbers and letters, used to represent the tolerance level of threads. The tolerance level of internal threads is represented by uppercase letters, while external threads are represented by lowercase letters. For example, thread tolerance levels are 7H, 6g, etc.

4. Spinning length

The length of thread engagement refers to the length required for thread engagement, which is generally divided into three types: short (S), medium (N), and long (L). If the thread engagement length is not indicated, the thread tolerance zone is determined based on the moderate engagement length (N). If necessary, the screw length code S or L can be added, such as "M20-5g6g-L". It should be noted that left handed threads should be labeled with "LH" after the thread length, with a "-" separating the thread length code from the thread direction code, while right handed threads should be omitted without labeling.

5. Rotation direction code

The rotation direction code is used to indicate the direction of rotation of the thread. Generally, only left-hand threads are labeled, while right-hand threads are omitted and not labeled.

6. Example of marking

M16-5g6g represents coarse pitch regular thread, with a nominal diameter of 16 and a right-hand thread. The thread tolerance zone has a pitch diameter of 5g and a major diameter of 6g, and the screwing length is considered to be of medium length.

M16x1LH-6G represents a fine pitch regular thread with a nominal diameter of 16 and a pitch of 1. It is left handed and has a tolerance zone of 6G for both pitch and major diameters. The thread engagement length is considered to be of medium length.

2、 The Importance of Representing Bolt Specifications

The representation method of bolt specifications is crucial for us to identify and purchase bolts. Only by accurately understanding the representation method of bolt specifications can the exact bolt size and tolerance level be identified. Therefore, when selecting bolts, it is necessary to have a clear understanding of the required bolt specifications, representation methods, and standards to avoid purchasing the wrong bolts.

In summary, understanding the representation method and marking examples of bolt specifications is crucial for us to purchase bolts. By studying the representation method of bolt specifications, we can more accurately identify bolts and select specifications and sizes that match the needs.