Electric Toothbrush Teardown

Behold as the electric toothbrush self-assembles!

Welcome to the Taodown! Otherwise known as the Tao Tao Teardown—brought to you by Becky Stern & PoD.

Today, we took apart a Philips Sonicare kids’ electric toothbrush. The short story? It’s made of metal and plastic. The long story—well, keep reading (and watching) below. Also, click here if you need your own—no commissions, sadly.

Tools & Techniques
To deconstruct the toothbrush, I used (1) my hands (2) a tiny screwdriver (3) a less tiny screwdriver (4) a wire cutter and (5) brute strength. The larger screwdriver was required as a lever to remove the plastic outer base of the brush, as well as dislodge both the control board and Li-Ion battery from the plastic skeleton. The tiny screwdriver was used to separate the oscillating brush head, cam, and gears from the shaft (which also held the motor).

Toothbrush teardown timelapse

Notable Design Elements
(1) It’s probably no surprise that Philips has made the Li-Ion battery next-to-impossible to remove. While electric toothbrushes are rechargeable, the battery will eventually run out, and if it does, you’ll need to buy a whole new unit. There’s no feasible way to replace that battery yourself. That being said, lithium batteries can be dangerous to handle, which means that until they are safe to handle, they should be kept as far out of reach (and replacement) as possible. In which case, a job very well done.

(2) I found myself contemplating the size of the removable toothbrush head. This, of course, is the “consumable” element of the product; the Philips website states that it is “recommended to replace your Philips Sonicare Brush Head every three months of normal use.” Looking at the inner underpinnings of the brush head, I wondered if the replaceable component could be reduced to just the very tip of the brush (just the brush, and no upper shaft), thereby reducing the amount of plastic. However, even if technically possible, Philips would almost certainly ignore this efficiency, because it would imply charging less for their brush replacement packs (a set of three currently retails at $31.96$42.96).

Electric Toothbrush: Parts

Electric Toothbrush Components & Materials:
1 – Toothbrush head (plastic + nylon for bristles—most likely Nylon 6-12)
2 – Outer case (plastic)
3 – Charging coil (copper)
4 – Induction charger coil (copper)
5 – Oscillating brush head + cam/gears (steel + plastic)
6 – Screws (steel)
7 – Motor (aluminum + copper)
8 – Torsion bar (steel)
9 -Magnet (iron, nickel, cobalt, +/or steel)
10 – Shaft, cam + gears (steel + plastic)
11 – Circuit board (copper, fiberglass, resin)
12 – Power button cover (plastic)
13 – Button cover / thumb grip (plastic)
14 – Lithium (Li-Ion) battery (lithium, nickel, cobalt, possibly manganese)

Electric Toothbrush: Circuit Board

Circuit Board Components:
1 – Power button
2 – Programming pads
3 – Coil connections
4 – Chip (#CY8C4247LQI-BL483)
5 – Diode bridge

Chip details
– Type: ARM Microcontrollers – MCU PSoC 4 BLE Integrated Chip; see data sheet
– Manufacturer: Infineon Technologies
– Price: $7.75 (for 1 unit)

Manufacturing techniques & equipment

  • Outer casing: These plastic elements are made from plastic granules, shaped while hot in molds along an mechanical assembly line. A computer scans the casing to ensure there are no flaws, and rays of UV light are blasted to make sure the plastic is completely sterile.
  • Head and bristles: Bristle color determines thickness (influencing the location on the center or perimeter of brush head). A machine inserts the bristles into holes in the plastic head by folding them around tiny pieces of wire. A blade cuts the tips of the bristles to ensure they’re all the same length, then blunts any sharpe edges. The necks are then attached the the brush heads.
  • A machine clamps the gearbox (cam + gears) and motor together. A worker then manually melds them together with the lithium battery, then plugs them into a charging unit to ensure the circuit is connected.
  • The inner components are then fitted into the casings via machine assembly.
  • A machine then seals the plastic bottom of the casing with a twist.
  • A quality controller gives them a final human review, while a subset of the batch are sent off for quality testing (performed by a machine). If that goes smoothly, they’re off to consumers!

Maybe we should all just be brushing our teeth with our fingers?

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