Table of Contents

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What does a fiber cleaver do?

When we need to join two optical fibers together, we usually use mechanical splice or fusion splice.

Mechanical splice

Fusion splice

Both optical fiber slicing techniques require that the fiber tips are a smooth end face that is perpendicular (90°) to the fiber axis as shown below.

And an optical fiber cleaver is the tool to cut (called cleave in the fiber optic industry) the fiber in such a good way.

How to cleave fiber optic cable?

In the cleaving process, the brittle glass fiber is fractured in a controlled manner as shown below.

The fiber is held with a tensile stress The fiber's surface is scratched with a very hard scribing tool, usually a diamond edge A sufficiently large surface crack (induced flaw) is made on the fiber surface This crack rapidly expands across the fiber cross section at the sound speed Two cleaved fiber tips are created

The crack propagation process is shown in the picture below.

A typical high precision fiber optic cleaver in action is pictured below.

This cleaving process is shown in the video below.

Cleave Defects

Since fracture is such a violent and difficult to control process, even the best commercial cleaver will sometime produce defective cleaves.

Some common types of cleave defects are shown below.

Lip

A lip is a projecting spike of glass at the periphery of the fiber tip.

Lip in a fiber cleave

Lips can be a serious problem when they are more than a few microns long, which is enough to interfere with the ability to gap the fibers.

Generally a fiber should be re-cleaved when it has a lip that is visible in the magnified image of a fusion splicer.

Chip

A chip is an absent section of glass on the periphery of the cleaved fiber tip.

Chip in a fiber cleave

Small chips are often of no consequence. Larger chips represent a deficit of material that will induce surface tension to shear the molten glass at the fiber tip, thus distorting the splice geometry.

Cleaved tips showing a chip visible in the magnified image of a fusion splicer should be re-cleaved.

Angle

Any torsion of the fiber during the cleave will result in an angle as shown below.

Angle in a fiber cleave

This is because a crack will propagate in a direction perpendicular to the local principal tensile stress. Torsion of the fiber causes the principal stresses of the fiber to be angled with respect to the fiber axis.

Angled end faces are a clue that the cleaving instrument is inadvertently applying torsion to the fiber; often the fiber clamps are the culprit.

If the end face of the opposing fiber tips are angled with respect each other, there will usually be a deficit of glass material when the fiber are brought together during the hot push. This deficit of material typically induces shearing of the molten glass, resulting in significant core deformation.

(a) Before splice during alignment (b) After splice

The cleave angle of the right fiber tip was about 5°. The geometric deformation of the core evident in the figure induced about 0.25 dB loss at 1550 nm

Fiber Cleaver Types and Their Applications

Pen-shaped fiber scribes

Pen-shaped scribes are used for scoring the fiber before polishing.

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This type is based on a traditional cleaving method. It is used for removing excess fiber from the end of a connector before polishing.

Fiber scribe tools are usually shaped like ballpoint pens with diamond tipped wedges. The scribe has a carbide or diamond sharp tip which scratches the fiber manually. Then the user pulls the fiber to break it.

Usage Procedure:

1. Gently draw the beveled edge of the blade across the fiber as shown below.

2. After lightly scoring the fiber, pull the fiber straight away from the connector to finish the scribe process. The fiber should shear cleanly at the scribe point.

Applications:

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 used in skilled hands, this scribe cleaver reduces the cost significantly for repairs, installation and training classes.

This video shows how to correctly use a fiber scribe tool.

Handheld pocket cleavers (stapler-style)

Stapler-style cleavers, such as Corning's FBC-002 cleavers, are used primarily for premise and campus installations (multimode applications in most cases) where precise cleaves are not required.

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They are also called Score and Snap cleaver as shown below.

These fiber cleavers are designed for cleaving fiber in the field quickly and easily. Corning's FBC-002 field cleaver is a single mode and multimode cleaver that has a ceramic blade with a life of at least 1,000 cleaves.

This type of cleavers do require some skill to achieve the desired angles, but its small, lightweight size makes it perfect for use in the field.

Usage Procedure:

Put the fiber in place on the leaf spring Press down on the base to score the fiber Use the lever to grip the fiber Bend the fiber and flexible leaf spring to break the fiber

This video shows how to use the Corning FBC-002 field cleaver.

Precision desktop cleavers

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.

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They can produce repeatable results through thousands of cleaves by simply rotating the wheel/blade accordingly. Although more costly, precision cleavers can cut multiple fibers at one time with increased speed, efficiency, and accuracy.

Capable of cleaving multimode, single mode, single fiber and up to 24 fiber ribbon fibers, high precision desktop cleavers provide up to 48,000 single cleaves or 4,000 12-fiber ribbon cleaves.

Most desktop high precision fiber cleavers are packaged with fiber scrap collectors.

Specialized application cleavers

Angled optical fiber cleaver

Sumitomo's FC-SE-AFC-08 angled optical fiber cleaver is a 1-step operation for easy, repeatable, and consistent eight degree cleaves for the mechanical splices and APC terminations. It has a preset 8° cleave angle without user adjustment.

80µm cladding fiber cleaver CT-38 from Fujikura

Fujikura's CT-38 cleaver is designed for cleaving silica fibers with 80μm cladding. It uses the same one step design of Fujikura's popular CT-30 cleaver.

Ultrasonic blade cleavers from Newport

Newport offers electronically tuned ultrasonic blade cleavers - the FK11 flat cleaver and FK12 angled cleaver. They are suited for both singlemode and multimode fibers.

The ultrasonically vibrating blade moves slowly toward the tensioned fiber on stictionless damped bearings. Cleaving then takes place without damage from compressive stresses and blade intrusion into the fiber that is typical of conventional cleavers.

These products target at applications where a consistent, defect-free, but angled cleave is required, such as for semiconductor laser diode manufacturing.

Fiber Cleaver Automatic Features:

Automatic Fiber Scrap Collection

Manufacturers now offer fiber cleavers with fiber scrap catchers that automatically collect fiber scraps.

These cleavers not only collect the fiber scraps, but also store the scraps in internal trash bins, ultimately saving cleaning and safe disposal time for the technician.

As a standard safety practice, fiber shards should always be collected and disposed of properly, since fiber can easily embed into the skin.

Automated Fiber Scoring Mechanism

Due to automated scoring mechanisms, cleavers can now complete a cleave and reset themselves for the next cleave in one or two steps, streamlining the cleaving process while perfecting the quality and reliability of the cleave.

Manufacturers now offer handheld clamshell-designed cleavers that complete the cleave with a quick and easy press-and-release motion.

Automatic Blade Rotation Cleavers

This feature is one of the breakthrough technologies in cleaver design. The automatic blade rotation system automatically rotates the cleaver blade during use for easy, fast, and precise cleaves in a two-step process that prevents double scoring of fibers and solves the field technician’s challenge of manually adjusting and rotating the cleaver blade position.



Standard cleavers cleave the fiber using the same blade position until that position becomes dull, resulting in poor cleaves. When this occurs, the technician must rotate and adjust the blade height, which can be a very time-consuming process.

Typically, with standard cleavers, the blade rotation process requires loosening a set screw and turning the blade to the next blade position. The height adjustment also requires loosening a different set of screws and raising or lowering the blade until it is in the optimal position, which can be determined by viewing the cleave angles on the technician’s fusion splicer. If the angle is not achieved, the process must be repeated.



In the past, the difficult process of blade rotation adjustments has necessitated increased service and maintenance of the fiber cleavers due to the frequent improper cleaver blade rotation and height adjustments.



Cleavers with automatic rotating blade systems utilize the complete blade surface (unlike standard cleavers) and automatically increment the cleaver blade with each cleave.

These auto-rotating cleavers remove the majority of the cleaver maintenance drudgery; provide 48,000 consecutive cleaves with no adjustments necessary; and extend the life of the cleaver blade; while resulting in an excellent typical cleave angle of <0.5 degrees.

Things to ask before buying a fiber cleaver

Select a cleaver that meets your application requirements.

Cleavers that are designed for fusion splicing require a low average angle that is one degree or less, while cleavers appropriate for mechanical connectors require angles below three degrees. Determine whether you require a single- or multi-fiber cleaver that can precisely cleave one to 12 fibers at a time.

Purchase your cleaver from a reputable manufacturer or distributor.

Tempting eBay and Craig’s List offers of cleavers at highly discounted prices abound on the Internet. As with fusion splicers, there are a host of illegitimate knock-offs that replicate the body, look, and branding of the leading manufacturers’ cleavers. Look at the inner components and you’ll likely find cheaply made parts and blades with inferior metal alloys that can compromise your splice or break down during the job.

By purchasing from reputable manufacturers, you’ll enjoy manufacturer support and warranties; service for periodic maintenance and cleaning that extends the life of the cleaver; and a cleaver made of the best durable metal materials.

Think twice before purchasing a cleaver built into a splicer.

The downside to these built-in cleavers is that if either the cleaver or splicer requires maintenance, the technician loses two valuable tools, which can hold up the job at hand.

Purchase a cleaver with the latest automation features that save time.

Cleavers, like fusion splicers, continue to evolve with new and improved features, such as automated fiber scrap collection, automated scoring mechanisms, and the latest automatic blade rotation technology.

Best fiber cleaver brands in the industry

AFL Fujikura







AFL Telecommunications, a subsidiary of Fujikura Ltd. of Japan since 2005, is widely recognized by the telecommunications industry as one of the foremost fiber optic solution providers.





AFL Telecommunications, a subsidiary of Fujikura Ltd. of Japan since 2005, is widely recognized by the telecommunications industry as one of the foremost fiber optic solution providers. Fitel (Furukawa)







Furukawa Electric Co., Ltd. was founded in 1884 and since that time has played a dominant role in the growth of the global marketplace.



Since manufacturing the world's first optical fiber cable in 1974, Furukawa has led the development of optical fibers by establishing a total production system for products ranging from high-performance silica-based optical fibers to a variety of optical fiber cables manufactured under the brand name "FITEL".





Furukawa Electric Co., Ltd. was founded in 1884 and since that time has played a dominant role in the growth of the global marketplace. Since manufacturing the world's first optical fiber cable in 1974, Furukawa has led the development of optical fibers by establishing a total production system for products ranging from high-performance silica-based optical fibers to a variety of optical fiber cables manufactured under the brand name "FITEL". Sumitomo







Sumitomo is most well known for their consistently high-quality fusion splicers which are now considered standard equipment by many technicians and engineers in the fiber optic field.



Sumitomo also manufactures a wide variety of other fiber optic tools including fiber cleavers, fiber jacket strippers, fiber holders and fiber arrangement tools. In addition they also manufacture a full line of optical cabling, cable assemblies and fiber management systems.

Fiber Cleaver Maintenance

Cleaver Blade replacement

Blade height adjustment

Blade rotation