A good fiber optic splices or terminations, especially when using the pre-polished connectors with internal splices, it is extremely important to cleave the fiber properly. If the fiber ends are not precisely cleaved, the ends will not mate properly. To prepare a fiber end for a connector or splice, the end of the fiber must be cleaved to a 90 degree flat end. For technicians the problem is that the end of the fiber strand is so small that it is impossible to tell with the naked eye whether the strand has a flat end. So in order for this to happen, you must use a cleaving tool called fiber optic cleaver. Some knowledge of fiber optic cleaves will be provided in this article.
What Is Fiber Optic Cleaver?
A cleave in an optical fiber is a deliberate, controlled break, intended to create a perfectly flat end face, perpendicular to the longitudinal axis of the fiber. A fiber optic cleaver is a tool that holds the fiber under low tension, scores the surface at the proper location, then applies greater tension until the fiber breaks. Usually, after the fiber has been scored, the technician will use a cleaver either bend or pull the fiber end, stressing the fiber. This stress will cause the fiber to break at the score mark, leaving a 90 degree flat end if all goes well. So the cleaver doesn’t cut the fiber. In fact, it just breaks the fiber at a specific length.
Two Types of Fiber Optic Cleavers
We know that the closer to 90 degrees the cleave is, the more success you will have with matching it to another cleaved fiber to be spliced or mated by a connector. So it’s important to use the proper tool with good technique to consistently achieve a 90 degree flat end. Good cleavers are automatic and produce consistent results, irrespective of the operator. The user need only clamp the fiber into the cleaver and operate its controls. Some cleavers are less automated, making them more dependent on operator technique and therefore less predictable. There are two broad categories of fiber optic cleavers, scribe cleavers and precision cleavers.
A traditional cleaving method, typically used to remove excess fiber from the end of a connector before polishing, uses a simple hand tool called a scribe. Scribe cleavers are usually shaped like ballpoint pens with diamond tipped wedges or come in the form of tile squares. The scribe has a hard, sharp tip, generally carbide or diamond, that is used to scratch the fiber manually. Then the operator pulls the fiber to break it. Since both the scribing and breaking process are under manual control, this method varies greatly in repeatability. Most field and lab technicians shy away from these cleavers as they are not accurate. However, if in skilled hands, this scribe cleaver offer significantly less investment for repairs, installation, and training classes.
Precision cleavers are the most commonly used cleavers in the industry. They use a diamond or tungsten wheel/blade to provide the nick in the fiber. Tension is then applied to the fiber to create the cleaved end face. The advantage to these cleavers is that they can produce repeatable results through thousands of cleaves by simply just rotating the wheel/blade accordingly. Although more costly than scribe cleavers, precision cleavers can cut multiple fibers while increasing speed, efficiency, and accuracy. In the past, many cleavers were scribes, but over time, as fusion splicers became available and a good cleave is the key to low splice loss, precision cleavers were developed to support various applications and multiple fiber cleaving with blades that have a much longer life span.