What is EN ISO 3129-3:2018

EN ISO 3129-3:2018 is a technical standard that defines the requirements for metric screw threads. This standard belongs to the ISO 3129 series and specifically focuses on external screw threads with a coarse pitch. The standard provides details on thread dimensions, tolerances, designations, and marking requirements for metric coarse screw threads. It plays a crucial role in ensuring compatibility and interchangeability of screws used in various applications.

Thread Dimensions and Tolerances

The EN ISO 3129-3 standard specifies the basic profile for metric coarse screw threads, including the pitch, flank angles, and crest diameters. It also provides tolerances for these parameters, which ensure that the manufacturing process can produce threads within acceptable limits. By adhering to the thread dimensions and tolerances specified in the standard, manufacturers and users can ensure that screws from different sources will fit together properly.

Designations and Marking

To facilitate identification and usage, EN ISO 3129-3:2018 assigns designations to metric coarse screw threads based on their diameter and pitch. These designations follow a specific format that includes alphanumeric codes representing the thread's nominal size and pitch. Additionally, the standard mandates certain marking requirements for screws, including visible markings on the screw head or nut, which further aid in identification and compatibility verification.

Applications and Importance

EN ISO 3129-3:2018 is widely used in industries where metric coarse screws are commonly employed, such as automotive, construction, machinery, and electronics. By providing a standardized set of thread dimensions, tolerances, designations, and marking requirements, this standard ensures that screws manufactured by different companies can be safely and reliably used together. It avoids issues such as loose connections, thread damage, or incompatible screw-nut combinations, which could lead to product failures, accidents, or assembly delays.

In addition to promoting compatibility and interchangeability, the EN ISO 3129-3 standard also facilitates international trade. By having a common set of screw thread specifications, manufacturers can easily communicate their product requirements and customers can confidently source screws from different suppliers around the globe, knowing that they will fit and function as intended.

Overall, EN ISO 3129-3:2018 plays a vital role in ensuring the reliability, safety, and efficiency of threaded fasteners used in various industries. Its comprehensive guidelines for thread dimensions, tolerances, designations, and marking contribute to easy identification, proper assembly, and consistent performance of metric coarse screws.