How It’s Made: Visonic Dome Stainless Steel Chamber

visonic dome blog stainless steel chamber
Like a good recipe, Visonic Dome production starts with quality ingredients. In this case, that means the highest grade of stainless steel.

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How We Make the Stainless Steel Chamber Inside Your Visonic Dome

Over the course of its design development history, Visonic Dome has gone through more than a few changes to become the iconic design that it is today.

But one thing has remained constant. And that’s the metal chamber that you fill with solution.

It’s able to withstand the incredible power of ultrasonic cleaning while also providing a clean environment for your contact lenses. But how is the metal chamber at the center of your Visonic Dome actually made?

Let’s find out!

visonic dome stainless steel chamber
Inside your Visonic Dome is a precision engineered, surgical-grade stainless steel chamber.

Making Stainless Steel

Like any good recipe, Visonic Dome production starts with quality ingredients. In this case, that means the highest grade of stainless steel.

If metal is a recipe, then the metallurgist is the chef.

He starts his stainless steel production with an iron alloy. To this, he always adds carbon and chromium. Chromium is what gives stainless steel its shine and luster and ultimately protects it from rust.

From there, other elements are added to enhance and refine the alloy.

Production might include aluminum, nickel, titanium, copper, and more, depending on the purpose of the steel. These combinations are standardized and graded by the American Iron & Steel Association and SAE International.

Today, there are over 150 different grades of stainless steel.

If you have a stainless steel sink or refrigerator in your kitchen, odds are that it’s 304-grade stainless steel. That’s the most common type.

But when you go to visit your doctor or dentist, their instruments aren’t made from 304-grade. And that’s because medical equipment is made with the more expensive, less corrosive 316 surgical grade.

The main difference between 304 and 316 is in the addition of a higher nickel content and another secret ingredient: molybdenum. The result is a metal alloy that’s harder and more resistant to wear and tear.

The Deep Draw

A hydraulic press stretches sheets of metal into the chamber shape.
Image source: AutoForm

Rolls of 316-grade stainless steel arrive at the metal production site in Singapore. There, the steel is fed into a hydraulic press.

This process is called a “Deep Draw.”

There are three main components that make up the deep draw:
At the top is the “punch.”
At the bottom is the “die.”
And in the middle is the “blank.” (That’s the roll of 316-grade sheet metal.)

Hydraulics press the punch down onto the blank. Then the force of the hydraulics stretches the sheet metal into the die until it takes on the desired form.

Imagine the deep draw like blowing a bubble with chewing gum. Poke your tongue into the gum too quickly or spread the gum too thin and it will tear. Similarly, the amount of force put onto the punch has to be specially calibrated to keep the blank from tearing apart or wrinkling.

hydraulic deep draw animation
The Deep Draw works by carefully stretching sheet metal down into the shape and size of the chamber.
Image source: YouTube

Precision Engineered

Careful calculation goes into every aspect of the metal chamber design.

As mentioned above, that starts with the dimensions of the deep draw tools. The size of the punch and die are precisely measured to determine the final thickness of the chamber walls and floor. That’s important for the Visonic Dome chamber because it acts like a bell for the piezo transducer mounted directly underneath.

A chamber that’s too thick won’t transfer the ultrasonic energy efficiently. Likewise, walls that are too thin won’t withstand the intense vibrations.

That attention to proportion extends further. You might find other ultrasonic contact lens cleaners online that brag about their small chamber size. The idea is that a smaller chamber will save you money by using less solution. But if your goal is cleaner, more comfortable contact lenses then that’s counterproductive.

The inner chamber volume is dictated by two things.
Firstly, the amount of solution needed to disinfect your contact lenses. And secondly, to create the optimal conditions for cavitation.

Using less solution might seem like a smart idea at first.

But like aspirin or any medication, your solution was clinically tested at a specific dose. Using less risks reducing its ability to disinfect your lenses. Likewise, lesser volumes result in reduced ultrasonic cavitation (the tiny bubbles that clean your contact lenses).

visonic dome stainless steel chamber design sketch
At the center of the Visonic Dome is the stainless steel chamber that you fill with your disinfecting solution.

Rust-proofing

Meanwhile, back at the production facility…

One by one, the sheets of steel get stamped into identical chambers.

Looking like little metal top hats, they clink and clang off of the press and into a receiving basket.

Once the hydraulic press finishes its run, an operator collects all 5,000 chambers and wheels them over to their next stop.

316-grade stainless is naturally anti-corrosive and rust-resistant. But since these chambers have to withstand the chemicals in contact lens disinfecting solutions, and because no amount of rust is safe for your contact lenses, the Visonic Dome inner chamber gets extra treatment to prevent corrosion.

Passivation

The first step sees the chambers loaded into a metal basket and then sprayed with a hot cleaning solution. That removes any dust or steel particles that might be leftover from the deep draw process. It also prepares the chambers for the next steps.

Then an operator immerses the chambers into a passivating acid bath of citric acid.
Passivation creates an invisible protective layer over the steel that prevents scratches or surface damage from rusting. All stainless steel already has this passive layer because of its high chromium content. But manufacturing processes (like the deep draw) can damage the layer and expose underlying iron particles.

Passivation removes those surface iron particles and restores the passive layer.

The passivating acid bath takes about 20 minutes. After that, the operator rinses the chambers again to remove the citric acid and moves them on to the next station.

Electropolishing

Lastly, we bathe the chambers one more time in an electrolyte solution. As the chambers soak in the solution, the operator runs a positive electric charge through the soaking tank in a process called electropolishing. The electric current reacts to the solution and smooths the surface of the chambers until it’s completely uniform.

You can imagine electropolishing like an ultra-fine grain of sandpaper working on a piece of wood. It removes any microscopic bumps, dings, or ridges in the steel.

The result is a stainless steel that’s shiny, featureless, and 30 times more rust resistant.

After a final rinse, the operator inspects the rust-proof chambers. She selects random samples to certify that the batch meets production standards. Then, the chambers get shipped to the final assembly site.

Just add chamber

At this point, the inner stainless steel chamber is complete.

It’s been stretched and pressed into its precise shape by a hydraulic deep draw. It’s been passivated and electropolished.

But it’s not yet the final step for these little guys.

Just outside the production facility, a cargo truck waits to transport all 5,000 chambers to the nearest port. From there, they’ll travel halfway around the world to the assembly site in the United States.

In a future post, we’ll put the completed stainless steel chamber inside the Visonic Dome – without any glue or screws or additional parts!

Beautiful. Simple. Iconic.

Do you like good design? Do you believe that beautiful products make your life better?
Visonic Dome is designed to clean your contact lenses with less effort. And it's beautifully simple.

Exclusively on Kickstarter, Visonic Dome is available only for a limited time. Back it early to get your "Early Bird" discount and save -20% off.

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