lens manufacture




Essilor lenses: quality at every stage

 

Essilor is present throughout the entire manufacturing process to manage all the design and production techniques used to produce your lenses. From manufacture, through finishing, to the sizing of the frames: let’s take a brief tour of the group’s expertise.

 

Making the lens

 

A technique for each material

Lens manufacturing procedures differ according to the material used. Depending on the cases, the result will be finished lenses or semi-finished lenses.

 

Polymerization

Used for thermo-hardened materials, including 1.5 index material.

Thermo-hardened materials enter the production process in liquid form.

 

Process of manufacturing lenses from thermo-hardened material

Stage 1: preparation of the monomer

The material is filtered and degassed, then combined with additives.

Stage 2: assembly of molds

The two lens walls are assembled together by a circular rubber joint and fastened by a clip.

Stage 3: filling

The empty space between the two walls of the mold is filled with liquid monomer.

Stage 4: polymerization

The filled molds are placed in water or air ovens where, over a period of several hours, they undergo a temperature cycle that causes the resin to harden. For certain materials, the molds may be submitted to ultraviolet rays.

Stage 5: unmolding

The joint and the walls of the mold are separated to release the lens. The lens is then inspected and treated as necessary.

Stage 6: varnishing

The finished lenses are given a varnish and receive further coatings as required.

Stage 7: delivery

Finished lenses are sent to the storage centers.

Semi-finished lenses are stocked in prescription laboratories for finishing.

 

 

Injection-molding

Used for thermoplastic materials, such as polycarbonate.

Polycarbonate enters the production process in the form of granules.

 

Process of manufacturing lenses from thermoplastic material

 

 

Stage 1: preparation of the material

 

The granules are dried with warm air then loaded into position on the press.

Stage 2: adjustment of the press

The molds are positioned and the machine is programmed.

Stage 3: injection

The plastic granules are fused and injected into the press.

Stage 4: cooling

The material is solidified by conduction through the mold.

Stage 5: unmolding

The press and the mold support-block are opened.

Stage 6: varnishing

All lenses made of polycarbonate are varnished.

Stage 7: trimming

Finished lenses are trimmed before receiving further treatment.

Stage 8: delivery

Finished lenses are sent to the storage centers.

Semi-finished lenses are sent to the laboratories for finishing.

 

 

Regular checks
In order to guarantee flawless products, quality controls are applied throughout the manufacturing process.

 

 

Finishing

 

Customizing lenses

Semi-finished lenses are delivered to prescription laboratories for on demand finishing.

 

The process of surfacing semi-finished lenses

Stage 1: grinding

The required curvature is given to the lens.

Stage 2: fine-grinding

The surface grain of the lens is fine-grinded.

Stage 3: polishing

This process gives the lens its optical quality and makes it transparent.

 

Little extras that make all the difference

Coloring for tinted lenses, anti-scratch or anti-reflective coatings: to guarantee greater comfort and satisfaction, Essilor deals with every customer demand on an individual basis.

 

Attention to detail at all times

A lens can undergo up to 60 operations during the finishing process. That’s why Essilor carries out regular checks that guarantee the optical properties, power and quality of its lens coatings.

 

Creating eyeglasses

Quality that is made-to-measure

In this final phase, Essilor delivers the round lenses to the optician / optometrist. These eyecare professionals are responsible for edging the lenses to fit the shape of the eyeglass frame.

 

The process of adapting the lens to the frame

Stage 1: centering

This involves identifying the optical center and the axis of the lens in order to ensure it is placed correctly in the frame. The distance between the pupils and the fitting height must be measured accurately. The shape of the frame is calculated and the measurements are transmitted to the edger, the instrument that is used to trim the lens.

Stage 2: edging / assembly

The lens is trimmed to fit the frame. The material and the power of the lens must also be taken into account here.

Stage 3: assembly

This stage in the process depends on the nature of the frame. Plastic frames are heated, while glass frames require screwing or piercing.


 
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