Here's how pairs of glasses are made in a factory

It’s more than just putting a piece of glass into a frame.
Christopher McFadden

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If you are unfortunate enough to need your eyesight corrected, then you are probably more than familiar with glasses. They come in a massive range of shapes and sizes but have you ever wondered how they are actually made? 

Let's find out, shall we?  

making glasses complete
Source: Interesting Engineering

Step 1: Making the frames

The first step when making glasses is to build the frames for the corrective lenses. These start out life, for metal ones at least, like spools of metal wire. 

These spools are first fed into a special machine that curves the metal wire into loops. The diameter and shape of the loops will vary depending on the final design of the glasses, but the basic process is more or less the same. 

Loops or metal wire and then cut off the main thread of wire, and collected ready for the next phase in the production process. 

making glasses loops
Source: Interesting Engineering

These loops are then soldered together to make the rims of the glasses as needed. With that done, other special machines are used to add the bridge and arms of the glass frames too.

For the bridge, the rims are placed on a special mounting frame, and human workers solder the bridge arch between the two. This is delicate work and requires skilled and experienced workers to complete it efficiently. 

making glasses frames
Source: Interesting Engineering

Once complete, the frames are collected and moved on to the next phase in production. Here human workers take each completed frame and give them a good polish using a rotary polishing machine. 

The metal is buffed, and solder lines are flattened and removed, where needed. This is judged by eye. 

making glasses polish
Source: Interesting Engineering

Step 2: Finishing the frames

Next, batches of frames are placed into a special frame ready for coating. Once ready, each batch of metal glasses frames is then dunked into a special hot liquid to add a protective layer to the metal frames.

making glasses dipping
Source: Interesting Engineering

This is for a variety of reasons including adding decorative features like color, etc, specific to the final design of the particular glass frames. This process may also include adding layers of plastic to the metal frame too. 

With that done, the glasses then undergo another round of polishing. In this case, the metal frames are added to a vibrating polishing machine in batches. 

making glasses vibrating polish
Source: Interesting Engineering

Once the vibrating polishing is complete, the next step is to assemble the frames. In this factory, this is primarily done by hand with arm hinges inserted into the rims. 

The completed rims are then passed to another set of workers who manually attach the arms to the hinges using mechanized screwdrivers.

making glasses hinges
Source: Interesting Engineering

Once that is complete, the frames with arms are exposed to another round of cleaning and treatment. With that complete, the frame is then spun in a series of racks to dry evenly.  

Yet another round of polishing then follows to refine the frames and ensure they meet the exacting quality standards of the factory. Other parts are then added to the frames like nose supports, etc, as needed.

Step 3: Making the lenses

With the essential parts of the frames now complete, the next step is to complete the most important part of the glasses -- the lenses. These start as discs of glass with specified optical properties. 

The lenses are then placed in special grinding machines to cut them down to size and shape to make the basic lenses for the glasses. These are not ground to meet prescriptions, but rather provide some example lenses for the generic frames.

making glasses lenses
Source: Interesting Engineering

While the lenses are being made, the frames are exposed to further processing. At some point in the process, branding is added to the frames where needed.

In this case, the customer's branding is added to the arms of the glasses using a special pressing machine. This automatically stamps the areas in question as needed. 

making glasses branding
Source: Interesting Engineering

Step 4: Fitting the lenses

With that done, the next step, and arguably the most important, is fitting the lenses into the frames. This, like other delicate parts of the process, is also done by hand. 

Human workers add some elastic cord around the eye lens holes in the frames, and then gently push the glass lenses into place within the frames.

making glasses fit lenses
Source: Interesting Engineering

This is done with great care to prevent damage to the lenses and frames. Eventually, the lenses will slot snuggly into place within the frames as required. 

The next step is to curve the rear of the arms using a specialist press to give the arms their dog-legged shape.

Once that is done, the glasses are then passed to the final phase of production - the final quality checks. Here specialist quality control staff give each pair of glasses a visual check and then test the balance of each.

Minor adjustments are made to the angle of arms as needed before each pair is then given another final polish by hand. 

msking glasses polishing
Source: Interesting Engineering

With that done, the glasses are then packaged and prepared for shipping out. 

If you enjoyed this behind-the-scenes view of how glasses are made, you might enjoy watching another industrial process in the works. How about, for example, seeing how socks are made?

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