Sems screws/bolts
Effortless assembly and reliable friction control
Sems screws are fasteners with an assembled washer under the head. While the washer is typically round and flat, Bulten can provide custom shapes and geometries based on customer requirements. These screws are also known as captive washers or combination bolts/screws.
Sems screws offer several advantages. They are easier to assemble than handling a separate screw and washer, especially for small dimensions. Additionally, they provide precise friction control during assembly, as the washer serves as the mating surface with the screw head.
Types
Flat washer
Conical washer
Serrated washer
Flags
Types of washers
Flat Washers
A Flat washer distributes the load of a bolt or screw, reducing surface pressure and preventing damage to the material. It helps create a more secure connection by minimizing loosening due to friction and uneven surfaces. This makes it ideal for protecting softer materials and ensuring even clamping force in assemblies.
Conical Wahsers
A conical washer provides a spring-like effect, maintaining tension and compensating for loosening due to vibrations or thermal expansion. It helps distribute load more evenly, reducing stress on the bolt or screw and preventing surface damage. This makes it ideal for applications requiring reliable preload and resistance to loosening over time.
Wave Washers
A wave washer acts as a spring, maintaining tension and absorbing shocks to prevent loosening from vibrations. It helps distribute load evenly while allowing slight flexibility to accommodate thermal expansion or material settling. This makes it ideal for applications requiring consistent preload and a balance between flexibility and stability.
Serrated Washers
A serrated washer enhances grip and prevents loosening by increasing friction between the bolt and the surface, making it ideal for vibration-prone applications. It also helps distribute load evenly and can penetrate coatings for a better mechanical or electrical connection. By resisting rotation, it reduces the need for additional locking devices like adhesives or lock nuts.
