Dyson Supersonic™ Hair Dryer Teardown
Written by
Sylvia Wu

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On
January 30, 2017
In
Teardowns

What did you get from Santa for the holidays? I’m sure it was great, but is it any better than a $400 hair dryer made by a company that really knows fluid dynamics?

We don’t meant to gloat, but we really think the greatest feeling of all time is receiving something amazing and expensive for the holidays, then immediately ripping it apart for knowledge. Destroying something so beautiful is never easy, though…

Dyson Supersonic Hair Dryer

Everyone loves a new hair dryer. It’s not only great for the hair on your head, it’s also great for the hair on your face. We sent this video to Dyson, thinking Dave might be offered a modeling contract, but we never heard back from them.

The Dyson Supersonic Hair Dryer in action

The major selling points of this hair dryer are, according to Dyson:

  • It uses a super quiet “Supersonic” motor, whose frequency is outside of audible range
  • The air temperature is controlled with a microprocessor that samples temperature at 20 Hz
  • The motor is placed in the handle, instead of the head, which is better for balance and results in less moment on your wrists
  • It’s compact, considering its high airflow throughput of 85 ft³/min

The Supersonic motor may be quieter than motors used in other hair dryers, but many other factors contribute the total noise output of the hair dryer. Sorry to disappoint, but the Dyson hair dryer does not operate beyond audible range!

We asked a few Fictors (a very scientific experimental method) what they thought of the noise emanating from the Dyson hair dryer, vs. that of a $30 drugstore hair dryer.  Some said there wasn’t much of a difference, while others thought the Dyson’s noise was more unbearable because it’s higher-pitched.

Not convinced that our $400 gadget could lose out to a competitor sold at 7.5% of its price, we record audio spectrograms for both. The drugstore hair dryer has several high amplitude peaks and is noisy across more audible frequencies. The Dyson hair dryer’s spectrogram shows overall lower amplitude, and the noise is concentrated in higher frequencies, validating our colleagues’ observation of “high-pitched noise.”

audio spectrograms for drugstore hair dryer on left and Dyson hair dryer on right
‍audio spectrograms for drugstore hair dryer on left and Dyson hair dryer on right

Therefore, we conclude that this hair dryer is especially great for older people who are losing their hearing at high frequencies. It’s the perfect gift for Mr. Santa, so he can dry his beard after a long night out in the snow.

All right, enough nerding out about audio; onward with the teardown!

The first part came off really easily with a twist…oh wait, that’s a filter cage, and it’s supposed to be user-removable! The fine filter mesh underneath catches debris and is cleanable. If you want to know how gross your room is, thanks to your roommate’s pet chinchilla, just run this hair dryer for fifteen minutes. The holes in the mesh filter allow air intake to the motor.

Dyson Supersonic Hair Dryer with filter cage removed

We remove some self-threading screws that secure the filter mesh, which reveals that the handle is composed of a structural part inside and a cosmetic enclosure outside. All grey-colored rigid cosmetic parts are coated with soft-touch paint. The paint is pretty high-quality and not easily scratched. The finish style is very much in line with Dyson’s other products.

Dyson hair dryer with filter mesh removed
Dyson hair dryer handle with structural part inside and cosmetic enclosure outside

Nothing else is budging after this point, so we move on to the head of the hair dryer.

The pink donut-shaped enclosure at the head’s rear (second air intake) end is constrained both by a twist lock and some cantilever snaps. The part is actually molded in black PC, but undergoes a process called physical vapor deposition (PVD) to get that metallic pink appearance.

donut-shaped enclosure at the second air intake end

The heat and fan speed control buttons are glued to a thin sheet of silicon rubber. The elastomer sheet provides springback for these buttons. The sheet is glued to the enclosure, and those holes are just locating features. Great DFA!

heat and fan speed control buttons glued to a thin sheet of silicon rubber

The buttons also undergo PVD to get their metallic appearance. Some masking is required to allow a bit of their original colors to peek through!

heat and fan speed control buttons

Next, the main PCBA comes out. The black bracket shown here is assembled to the pink donut via snap fits. It provides masking for the LEDs, and the PCBA attaches to it by self-threading screws.

black bracket shown that attaches to the pink donut

Those are some sizable capacitors! Gotta be careful...getting shocked is bad for worker’s comp premiums!

capacitors

There’s actually a small arc-shaped PCBA stacked on top of the donut-shaped PCBA. Yay for unusual and fun shapes; not so yay for efficient PCB panelization.

There are two power module chips on the lower PCBA; they’re Infineon IRSM808-204MH half-bridge modules, which are specifically designed for appliance motor drive applications, such as energy-efficient fans.

The microprocessor, which is responsible for “intelligent heat control”, is a Microchip PIC16F1939-I/MV MCU. It’s only $1.64 if you order 5,000 or more—cheap!

microprocessor

On the back side of the lower PCBA, you can see the pushbutton switches for heat and fan speed control, as well as six tiny status indicator LEDs.

The black cylinder soldered to the PCBA via black and white wires is an anion (negative ion) generator. Anions bond to positively charged particles such as dust, cleaning the air. This component is often found in room fans. Plenty of fancy hairdryers claim to make use of “ionic” technology, which reduces static and makes your hair less frizzy, but the effect is temporary, lasting only as long as the hairdryer is on. It’s interesting that Dyson does not explicitly market its hairdryer as ionic, but they do SEM on that keyword.

PCBA

The outer handle enclosure slides off after we violently pry off the power and cold shot buttons (those were just glued on).

outer handle enclosure

We’ll call this part the switch cover. The multi-shot part allows the button tops to slide and push the switches below, while providing a waterproof interface.

switch cover

The inner handle is actually two halves. We finally found the supersonic motor!

the handle's two halves with the supersonic motor inside

The motor is encased in a Bowser-like silicon rubber sleeve to reduce vibration against the handle. This is Dyson’s “Digital V9” motor, which is fancy marketing speak for a brushless DC motor.

Dyson’s Digital V9 motor

The impeller attached to the motor shaft is machined on a five-axis mill. This is probably one of the most expensive parts in the entire assembly. In contrast, impellers found in Dyson’s vacuums are molded in fiberglass. The blades of the impeller are responsible for sucking hair into the hair dryer.

 impeller attached to the motor shaft

Let’s go back for a closer look at the head. See those six arc-shaped slits? That’s the secret of how this hair dryer works…

Dyson hair dryer head

Dyson’s marketing copy mentions that the hair dryer incorporates “air multiplier technology,” just like the brand’s fans. In fact, the hair dryer works very much like Dyson’s bladeless fans. This is how it works:

  1. Air gets sucked into the bottom of the handle, through the filter mesh, and gets pushed into the interior of the donut-shaped head at high speed.
  2. As the air passes through the heating coil, it’s brought up to the desired temperature.
  3. Air is propelled out of the donut-shaped head, through thin slits in the head enclosure.
  4. As air gets pushed out of the front of the head by the motor, this flowing airstream  induces the air behind the fan to follow. This is called inducement.
  5. Air surrounding the edges of the hair dryer head will also begin to flow in the direction of the airstream coming out of the hair dryer head. This is called entrainment.

Thanks to inducement and entrainment, the total air output of the hair dryer is much greater than the amount of hair that the motor moves, hence the term “multiplier.”

The hair dryer comes with three styling attachments. Conventional hair dryer attachments are usually threaded or snap-on, but Dyson’s attachments are magnetically attached to this stainless steel ring in the head of the hair dryer.

attachments attach magneticallyto the stainless steel ring in the head of the hair dryer
magnetic metal ring for hair dryer attachments

The component that holds the steel ring between itself and the head enclosure also assembles to the head enclosure by twist locking. There are many instances of thread locks in this hairdryer, but given the fact that everything’s cylindrical, this is no surprise.

component that holds the steel ring between itself and the head enclosure

This small electrical component is a glass bead thermistor, which is responsible for closed-loop air temperature control, so your precious locks don’t get fried.

glass bead thermistor

Here’s a look at the twist lock features inside the head.

twist lock features inside the head

Finally, we rip out the heating elements out of the head. It put up a good fight. There’s a mica insulating sleeve around the heating elements that prevents the plastic housing from getting too hot and burning your hands.

heating elements

Now that you’ve seen the innards of this $400 hair dryer, is it magical enough for you to drop a wad of cash on it? Its BOM cost is probably lower than its cordless vacuum and bladeless fan cousins, but ultimately, a luxury product’s sticker price has more to do with value perception than BOM cost.

Written by
Sylvia Wu
Fictiv Manufacturing Engineer. My favorite products are the ones I get to assemble.
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