SEMS screws, also known as combination screws. A SEMS screw consists of a screw with a washer pre-attached to it. The washer can have external teeth (lock washer) or be a flat washer and spring washer. The purpose of the washer is to provide additional grip and prevent loosening of the screw in applications that may experience vibration or movement. SEMS screw are commonly used in various industries, including automotive, electronics, and machinery.

Do you know what is difference with 2 parts SEMS screw and double washer screw?

The main difference between a 2-part SEMS screw and a double washer screw is the addition of a spring washer. From its appearance, we can see 2-part SEMS screw consists of a screw pre-assembled with a flat washer or an external lock washer. On the other hand, a double washer screw includes a screw pre-assembled with a flat washer and a spring washer.

Then from the performance of SEMS screw, double washer screw with a spring washer, the purpose of the additional spring washer is to provide a higher degree of resilience in the connection, as it can compress and expand in response to movement or vibration. The result is a more secure and reliable fastening for applications that require extra durability, such as heavy machinery, automotive and aerospace industries.

In summary, while the 2-part SEMS screw provides basic resistance to loosening, double washer screw with a spring washer offers greater locking capacity and is more suited for applications where vibration and movement are present.