Aisin used vibration to line up washers no one wanted to count

Aisin (then Aisin AW) needed steel washers stacked in order for its transmission assembly. Workers picked up loose washers a few at a time and threaded them by hand onto a supply rod about 300 mm long.

Each rod held around 250 washers and took roughly five minutes to fill, and the job repeated about 12 times a day, totalling about an hour. It was slow and, because the washers were small and metal, easy to drop.

The fix was a no-motor mechanism: a vibrating container and acrylic tube. The vibration spins and aligns each washer so it slips onto the rod by itself, using the same self-orienting principle as the 'garigari tonbo' toy that spins when spun on its stalk. The unit that does this is roughly 60 cm long and took the grand prize at the 25th Karakuri Kaizen Exhibition in 2020.

Let vibration, not fingers, align the parts

Vibration does the repetitive work that fingers were doing, so the task runs without an operator.

No power source means no sensor, motor or air line to buy or maintain.

A consistent single-file stack removes the misalignment that caused downstream jam or scrape.

The mechanism is small and made in-house, so the payback is almost immediate.

Find the geometry that lets a part orient itself under a tiny repeated force, and you replace a tedious, error-prone manual task with a cheap mechanism that never gets tired.

The 'Zenshuuchuu! Washer Alignment no Kokyuu' device became a widely published example of karakuri (no-power automation) in Japanese manufacturing media. Aisin has a history of such mechanisms; the company continues to field innovations in its plants and at the karakuri exhibition.