Sometimes fiber optic cables are routed through and around machinery. A rule of thumb when specifying sheathing: if interlocked metal ((SL)), plain or covered) sheathing is used, minimum bending radius is 4X the OD of the sheathing. “S. Sometimes fiber optic cables are routed through and around machinery. A rule of thumb when specifying sheathing: if interlocked metal ((SL)), plain or covered) sheathing is used, minimum bending radius is 4X the OD of the sheathing. “Soft” sheathing such as PVC or Silicone can withstand a bending radius as small as 2X the ODGlass fiber and plastic fiber is fragile. When individual fibers break, light transmission and uniformity are reduced. After the first few fibers break at a stress point, a chain reaction occurs, hastening the destruction of the part. Surrounding fiber with a jacket or sheathe protects it from abrasion. Sheathing typcially has a larger bend radius,. For applications requiring minimal handling, where the application is illumination, and heat exposure is low, consider inexpensive PVC sheathing. PVC offers good protection from corrosive mists and foreign debris, as well as protection from incidental abrasion and contact. This material is also manufactured in corrugated shape, offering some crush. For repeated handling, where the application is illumination, and heat exposure is low, consider monocoil, which provides moderate crush and kink resistance in addition to debris protection. This choice is lighter and more flexible than SL type sheathing. In addition, it's available in many more ID/OD selections, making an efficient and cost effect. For repeated handling around big equipment, where heavy objects can fall on, roll over, or simply compress the component, and where the application is illumination, and heat exposure is low, consider PVC covered stainless interlock (SL), which provides the best crush and kink resistance in addition to debris protection. This material is the most ex.