The technique with which optical fiber is handled can have a significant impact on the functionality and reliability of a manufacturer’s final product, whether that be an optical fiber cable, a photonic networking component or a fiber-optic gyroscope. The cost of rework or replacement due to improper handling can also be significant, resulting in monetary losses and increased processing times. This article will give some suggestions for the proper handling of optical fibers, which should be considered during the design and implementation of a fiber handling program specific to a user’s application and manufacturing process.
The categories of fiber damage will be introduced before illustrating the suggestions. Generally, there are four categories of fiber damage, which are fatigue damage, compressive damage, abrasive damage and particulate penetration.
Fatigue is defined as the slow extension of a flaw over time due to the application of a tensile stress in the presence of moisture or humidity. The implication of fatigue is that a fiber may degrade in strength over time if placed under a considerable stress. This stress could be in form of a pure tensile, bending, or torsional stress, or any combination thereof.
Compressive damage may occur when a fiber is pinched, clamped, or constrained to a point where the coating or glass layers become damaged. This can result in several effects depending on the severity of the compressive force, including coating delamination, coating damage (splits, cracks), and strength degradation due to the introduction of flaws onto the glass surface.
Abrasive damage may occur when a fiber comes into sliding contact with a sharp object such that it is scratched or scraped. This may result in damage or removal of the polymeric coating from the fiber. There is also a high likelihood that the contact event may damage the glass surface of the fiber, creating flaws that reduce the fiber’s strength.
Particulate penetration occurs when a hard particle, such as glass or ceramic, penetrates the coating layer of a fiber. This can often be initiated due to poor process cleanliness, and exacerbated by static electricity and subsequent processing.
Always follow the recommended applied stress design guidelines for optical fiber. Generally, these rules dictate that a fiber should not be subjected to a stress higher than one-half the proof stress for a time on the order of one second, and to no more than one-third the proof stress for a time on the order of four hours.
- Never place tools, fixtures, components, etc. on top of an optical fiber.
- Do not over-tighten wire ties, tie wraps, or other objects used to constrain optical fiber.
- Avoid the use of tweezers or other such tools to handle optical fiber.
- If fiber is clamped during processing, ensure that the clamping pressure is limited so that damage is not induced. Any clamping materials that physically contact the fiber should be smooth, pliable and nonabrasive.
- Never allow a fiber to contact an uncontrolled surface where it may be stepped upon, rolled over with a chair castor, etc.
- Do not allow an optical fiber to come into contact with a sharp or jagged edge or work surface.
- Regularly check any pulleys or other hardware that the fiber may contact for nicks, burrs, corrosion, etc. All surfaces should be smooth and free of any debris or defect.
- Never wipe an optical fiber with an abrasive material or with organic solvents such as acetone.
- Take care with fingernails and jewelry when handling optical fiber.
- Never allow a fiber to contact an uncontrolled surface where it may become snagged or otherwise abraded.
- Clean all surfaces that contact the fiber regularly.
- Do not cut or break fibers directly over work surfaces. This creates a high stress fracture and may release numerous microscopic shards of glass over the work surface.
- Never allow a fiber to contact an uncontrolled or dirty surface where it may contact particulate material.
- Check pulleys, work surfaces and other hardware regularly for the presence of corrosion or other contamination.
- Control static electricity. This may reduce fiber tangles, as well as attraction of particulate to the fiber.
- Ensure that any bins or receptacles used to hold or contain fiber are free of debris.
Suggestions have been presented for the proper handling of optical fiber. These guidelines are intended to reduce the occurrences of fiber damage or breakage and are applicable to a wide range of processes and applications. Following these guidelines is an important step in creating a functional and reliable product utilizing optical fiber, as handling and processing procedures may have a significant impact on the strength and reliability of a final product.