Buttress-thread forms are a type of screw specially designed to handle extremely high axial thrust. The thread profile of buttress threads typically features perpendicular edges and strongly slanted trailing faces. This design enables them to exert a strong force in one rotational direction while being able to release quickly.
In comparison to square threads, buttress threads provide twice the shear strength. Their unique ability to handle unidirectional loads and transfer immense force leads them to be widely used in vertical lifting applications, large screw presses, and more. Jerpbak-Bayless is a trusted source for highly specialized component parts, including buttress threads.
How Do Buttress Threads Work?
Buttress threads feature an asymmetrical profile that makes them suitable for extremely high, single-direction axial loads. They work by utilizing a load-bearing thread face that is perpendicular to the screw axis or length of the bolt and is characterized by sharply slanted trailing edges that resemble waves. This unique pattern exerts a powerful force that releases quickly and easily.
The leading slanted edges on buttress threads can be between 3° and 7°, while the trailing edges are typically at angles between 33° and 45°, depending on the needs of the application it’s used in. Buttress threads are required for vertical-lifting applications where the load is firmly supported on the screw thread’s upper flank. Using split nuts allows buttress threads to also resist deterioration.
Applications of Buttress Screws
Screws featuring a buttress-thread profile are primarily used in vertical-lifting applications that require the load to be supported on the upper flank of the screw thread. Buttress threads are uniquely well suited for single-directional axial loads and have the added benefit of an extremely high load capacity. Some common applications of buttress screws include:
- Artillery equipment
- Transmission threads in milling and turning equipment
- Heavy lifting equipment applications
- Friction screw presses
- High-load machinery applications
Additionally, buttress threads are used to open and close bench vices where tensioning power is required in only one direction. Its design is also well suited to environments involving viscous liquid seals, such as throughout the oil field industry. In these types of applications, the screw’s one-way parallel axis force enables securely sealed joints to be re-tensioned quickly.
Specifications and Capabilities of Buttress-Thread Screws
Depending on the size specifications of the screw that the customer requests, buttress-thread screws feature a wide range of capabilities. Buttress-thread screws are available in a wide variety of sizes and diameters ranging from 1 in. to 12 in. Depending on the size, the static load rating ranges anywhere from 17,000 lbs. to 3,300,000 lbs. and operating load ratings between 5,700 lbs and 965,000 lbs. The screw weight also varies greatly depending on size and can range from 2.4 lbs./ft. to 367 lbs./ft.
Order Custom Buttress Threads from Jerpbak-Bayless
Since 1945, Jerpbak-Bayless has been providing custom machining services for a range of industries, including manufacturing OEM components for heavy industry. Our 42,000 sq. ft. manufacturing space allows us to deliver orders of all sizes using CNC turning, milling, helical milling equipment, and more. We are also compliant with ISO-9002 and MIL-I 45208 standards. We welcome challenging jobs that demand high precision or have unusual specifications.