How to make your fiber optic polishing work to be correct and how to revise your fiber connector polishing

 

When you polishing a fiber connector or several connectors in polishing holder, by fiber polishing machine or fiber polisher, there are procedures and setting parameters designed to leverage the machines best practices as well as previous developments and experience.

 

Additionally, there are tips to consider applying during daily production to improve first pass yield, efficiency and results to avoid scrapping costs.

 

The standard polishing process includes three steps:

 

• Epoxy Removal
• Geometry checking
• Final Step: finishing the fiber connector end-face, check optical surface

 

Below we share tips for each step of the fiber polishing process:

 

• Epoxy removal

 

Pre- Polish

When connectors are loaded on the polishing fixture or fiber polishing holder jig after cleaving, there are large, sharp edge fibers and inconsistent fiber protrusion due to different fiber cleaves.  This can result in fiber breaks if polishing, by machine, is started immediately.

 

Tip: start polishing the connectors loaded on the jig with SC Film mounted on the rubber pad and then by hand/air delicately, with little hand pressure making few rotations (around 10).  Next the fiber protrusion has more consistent length distribution over all ferrules resulting in less fiber breakage (fiber into ferrule bore hole).  After this initial operation, one can start polishing with the machine using the same film used for air polishing.

 

LC Conical

 

The available surface of the 1.25 mm connector is small and sometimes due to this limited surface, epoxy is also going to the base of the chamfer area that you cannot remove using the polisher.

 

Tip: After the epoxy removal step on the polisher, if some epoxy is still present on the chamfer area, use a little scalpel to remove residues. This will allow to move to the next step (Geometry) avoiding any contamination on D films.

For other types of ferrule (2.0 or 2.5 mm) it is a good practice to check, after epoxy removal, if all the epoxy has been polished away (checking the front face of the ferrules).

 

Fiber Polishing Jig Holder Locking Mechanism with Individual Ferrule

 

A fiber polishing fixture or holder jig where the ferrules are independently moving from the each other is called Individual Pressure Control (IPC) fixture and is recognized by the use of spring loaded adapters to lock and to keep the ferrule in place.

 

Tip: after checking if there are not any epoxy residues left, it is a good practice to verify if all the connectors are well positioned (same height) and if the spring of each adapter is working properly with the ferrule moving freely - not stuck due to polishing residue. This guarantees each ferrule will be under the defined fiber polisher pressure in the polishing steps offering more consistent geometry results.

 

• Geometry Checking

 

Air Bubble Under Fiber Polishing Film

 

A common occurrence after positioning on the rubber pad is air bubbles under the fiber polishing lapping film.

When this occurs, it must be removed because during the geometry polishing process as the air cushion can modify the ferrule geometry (radius and/or apex).

 

Tip: to avoid this effect, use a roller to press down the lapping film on the rubber pad. It is important to have a different roller for each type of film to avoid contamination especially from D film to final film.  If one uses the same roller, it is essential to clean it before moving to the smaller film grid.

 

Tip: when using just one roller, to avoid contamination, take two films one on top of the other (one on top upside down) and then use roller. The lapping film that will used for polishing connector will not be effected by any cross-contamination.

 

Fiber Polishing Film Longer Life

 

Diamond fiber lapping film is the most expensive film we use on the polishing process and one consideration when selecting a supplier is the number of times you can use it.   There are fiber polishing films used for 10, 15, 25 times, or even longer depending on the process and specific customer specifications.

 

Tip: after a certain number of usage, typically 10 times, if you clean the surface with alcohol you are able to extend the life of this film (using alcohol removes debris from previous polishing).

VIEW: Diamond Films Product Matrix

 

Fiber Polishing Rubber Pad

 

In a polishing process, we use rubber pads typically 60 to 80/85 durometer.  Keeping consistent geometry can be a challenge.

In principle, a rubber pad that is too soft can help to reduce radius but effect negatively the apex.

Using a harder pad with higher pressure should be better to get positive radius and apex results.

 

Tip: always try to develop a process using pads with same durometer throughout the entire process. Changing the hardness of the fiber polishing pad will effect radius and/or apex and can make it difficult to bring both parameters within the specification.  Usually adjusting pressure and timing, using the same pad, can achieve desired results.  If you do need to change to a softer pad, decrease the durometer maximum by approximately 10 durometer.

 

Choice of APC connector holder/Jig According to Connector Style

 

In the market there are two different types of ferrules: Stepped and Conical.

As soon as you select the connector style, you need to consider the related fiber polishing fixture holder jig.

 

Tip:

Stepped Ferrule - require a jig with an APC angle of 8°

Conical Ferrule - require a jig with an APC angle of 8.3°