Loopback testing of a medium length span. Loopback testing of a medium length span.
Sep 22

What to Look for in a Cleaver

Many types of cleavers are used in today’s fiber applications — from simple “score and snap” types with carbide or ceramic blades to high-precision automated models with diamond blades.  Determining which of them is best is ultimately dictated by the application and budget on hand.

Splices and splice-on connectors, both mechanical and fusion, require the highest quality cleaves to achieve the lowest loss and reflection. It is recommended that the cleave angles are a maximum of 1° of perpendicularity to the fiber axis. Nearly-perfect 90° cleave angles are achievable with high-precision diamond and carbide blade cleavers if the fibers are properly stripped, cleaned, and placed into the unit.

Hand scribes are used when preparing plugs prior to polishing, and are not recommended for splicing because they usually produce an uncontrolled angled cleave. This type is used mainly with the connectorization process where polishing will create the final end finish.

Stapler — or “score and snap” — cleavers have carbide or ceramic blades that are good for mechanical splicing, but not recommended for fusion splicing. The fiber is placed in a retainer and the blade is brought down to lightly scratch (or scribe) the fiber. After the blade is released and the leaf spring is bent, the fiber will break at the scored location. The blade is good for as many as 5,000 cleaves with a cleave angle typically less than 2°.

Angled cleavers are most often used with field-installable connectors or mechanical splices, and allow mechanical splices to be used with low reflectance values. They perform tensioning, twisting, and cleaving with one action, and cleave the endface to ~8°. They generally have 16 stages with 1,000 cleaves each, and a 30,000 cleave maximum blade lifetime. 

Precision diamond cleavers are recommended for fusion splicing. These cleavers offer adjustable cleave lengths with V-grooves for 250-µm and 900-µm coated fibers and provide consistent cleaves. Some cleavers have 16 or more positions, with each position capable of up to 3,000 cleaves. Optional fixtures allow for cleaving ribbon fibers.

A precision cleaver is required when splicing ribbon fibers, as anywhere from two to 24 fibers must be cleaved at the same time with typical accuracy of approximately 0.5°. Most of these cleavers have a 16-position carbide blade, allowing them to perform up to 4,000 cleaves on a 12-fiber ribbon before the blade must be replaced.