FSC 5305 – Screws

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FSN Catalog    FSG 53 – Hardware and Abrasives    FSC 5305 – Screws

Federation Supply Class 5305 covers all types of screws. Screws are a type of fastener, in some ways similar to a bolt, typically made of metal, and characterized by a helical ridge, known as a external thread (or "male thread"). Screws are used to fasten materials by digging in and wedging into a material when turned, while the thread cuts grooves in the fastened material that may help pull fastened materials together and prevent pull-out. There are many screws for a variety of materials; those commonly fastened by screws include wood, sheet metal, and plastic.

Types[edit | edit source]

In most cases screws and threaded fasteners used by Starfleet conform to the ISO metric screw thread definitions as codified in ISO 261 which were developed by the Interplanetary Organization for Standardization. Most standardized screw types within the ISO standard fall within two basic categories, machine screws and socket screws.

Machine Screws[edit | edit source]

ISO metric machine screws are limited to four different head shapes: countersunk, raised countersunk, panhead, and isotrap head. In almost all engineering applications, particularly spacecraft or aerospace flight hardware, the screw drive typically used is the Torq-set offset cruciform configuration.

Basic profile of ISO metric screws

Socket Screws[edit | edit source]

ISO metric hexagon socket screws are limited to two different head shapes: cap screw, and countersunk socket screw. All head dimensions are directly related to the basic screw diameter as follows:

Basic profile of ISO metric socket screws

Coatings and Materials[edit | edit source]

Plasma electrolytic oxidation or Keronite, is used to treat screws and other separable parts that are expected to be used in vacuum conditions such as space. This prevents the phenomenon of cold welding.

List[edit | edit source]

External links[edit | edit source]