The Past and Present of a Lens
Lenses, I believe everyone is familiar with them,Every day, there are "lenses" in the mouth and hands.When it comes to the parameters of lenses, many people can easily grasp them, such as refractive index, specific gravity, coating, Abbe number, and so on.But do you really understand the production process of lenses?
Do you know how many processes it took for the small lens in front of you to reach your hands?Today, we take you into the production workshop to let you know what it is and why it is.From the perspective of production steps, the production of substrates involves a total of 12 steps.
1.Raw material configuration
The raw material configuration workshop mainly carries out the configuration of monomers and auxiliary materials,Different refractive indices require different raw material monomers,Mainly including CR-39 (1.499), NK-55 (1.56), and discoloration, etc,and also need to add auxiliary materials such as UV powder (anti radiation), toner (to prevent yellowing of lenses), antioxidants, additives, etc.
The precision monomer configuration filtration system, vacuum pumping, exhaust and other pre configured monomers are output to the separate storage tank, stirred for a certain period of time, and then transferred to the pouring bucket for discharge and vacuum pumping before being put into use.
2.Mold assembly
The mold is divided into A mold and B mold, which are glass molds because glass has a high melting point.
There are two assembly methods for mold assembly,Combine clean molds in different ways according to different production plans and mold ratios,
One method is the rubber ring method, which uses artificial lamination to produce 1.499 lenses. The rubber ring is made of plastic, elastic, and heat-resistant polymer material that can be recycled. The cleaning and protection of molds are also crucial. There is a dedicated assembly line for mold cleaning, which includes 19 tanks such as strong alkali, dichloromethane, and pure water.
The second method is the tape method, which uses machine laminating. The service life of special tape is only once, so the cost is relatively high.
3.Pouring
By pre polymerizing according to a certain formula to achieve a certain viscosity,
Inject the pre polymer after vacuum degassing to ensure it is fully filled, does not overflow, and has no bubbles.
This job requires experienced workers to operate.
4.Curing
Send the filled mold to the curing furnace (heating furnace), and set different curing curves according to different specifications of products, and input them into the temperature control system. After a certain period of heating, the CR-39 prepolymer continues to undergo polymerization reaction, ultimately transforming from a viscous liquid to a transparent solid.
1.50 (78 °) 1.56 (82 °) 1.60 (115 °), the temperature required for raw material monomers with different refractive indices varies, and the time is approximately 20 hours.
Function: To transform the raw material from liquid to solid, basically forming, eliminating internal stress in the lens, preventing lens deformation, and preventing edge breakage in future processing.
5.Demoulding
Firstly, remove the tape and sealing ring. Then, use compressed air (4kg) from a blowing gun to separate the lens from another glass mold. The removed sealing ring should be recycled and the tape can only be used once. After demolding, the mold is sent for cleaning and processing, and the middle substrate is subjected to edge cutting and cleaning treatment.
6.Edge cutting
The cutting of the lens surface makes the edges of the lens smooth, the surface flat, and there is no edge breakage.
Before edge cutting, the lens should be soaked in the liquid in the upper protective film. To prevent damage to the lens during edge cutting, it should be soaked and dried before edge cutting. During the edge cutting process, the surface of the lens should also be inspected to see if it is qualified.
After passing the inspection, send the lens for cleaning.
7.Lens cleaning
The surface of the trimmed lens must be cleaned due to the presence of unreacted CR-39 and ground solid powder,
In general, cleaning agents and solvents are used for multiple cleaning under the action of ultrasound.
There are approximately 19 cleaning tanks involved in the process.
Then, it will be inspected and deemed qualified before undergoing secondary curing.
8.Secondary curing
The function of secondary curing: 1. Eliminate internal stress of the lens and prevent edge breakage during processing;
2. Smooth out small scratches on the surface of the lens and harden the lens.
The time and temperature for secondary curing are also specified. The lens after secondary curing is called the "substrate".
9.Inspection of substrate
There are two aspects to inspection:
1. Wipe and inspect the surface of the lens with acetone;
2. Whether the refractive power, prism power, center thickness, refractive index, etc. of the lens comply with the national standard,There are adhesive error standards on each worker's workstation.
After passing the inspection, the substrate packaging is stored and waiting for hardening and coating.
10.Inspection before hardening
Before hardening the lenses, there is also a pre hardening inspection, and qualified lenses undergo hardening treatment.
Before hardening, the lens should be cleaned to remove any oil stains from the surface, roughen the surface to make it easier to absorb additional hardening fluid, and then dry and wait for hardening.
The steps can be summarized as: cleaning - drying - hardening - drying - testing.
11.Coating
Coating is a process of vacuum ion sputtering, in which high refractive non-metallic oxides and metal oxides are melted and sputtered onto the surface of the lens, forming different colored coating according to spectral differentiation.
Function: Fully improve the transmittance of the lens to over 97%, making the lens beautiful and fashionable.
12.Coating inspection
Check whether the coating on the surface of the lens is uniform, whether the coating has falled off, and whether it has radiation resistance.
Usually, salt boiling experiments are used to randomly check the coating quality of lenses.
The experiment involves boiling the lens in 5% saltwater at 96 ℃,
Every two minutes, repeat six times, observe whether thecoating falls off. If it falls off, the batch of lenses should be recoated
Each lens goes through 12 processes before reaching the hands of consumers, and each process involves the hard work of eyeglass enthusiasts.