Mizusumashi = 水澄まし (mee-zoo-soo-MAH-shee)
A Water Spider, sometimes called a Mizusumashi, is a dedicated operator whose job is to deliver materials, tools and information to workstations on a repeating cycle, so that the workers on the line never have to leave their station. The name evokes the graceful movement of a water strider skating across a pond.
Follow a defined route on a defined cycle time, often 15 or 30 minutes. At each station, deliver the next set of materials, remove empty containers or Kanban cards, and check for any issues. Return to the supermarket to reload, then repeat. The cycle is predictable, so every workstation knows exactly when the next delivery will arrive.
Without a water spider, either operators leave their stations to fetch materials (creating motion waste and interrupting flow) or materials are delivered in large batches (creating inventory waste at the workstation). The water spider allows small, frequent deliveries, supporting one-piece flow, without ever taking the operator off the line.
The route follows a fixed path with fixed stops. Cycle time is set to match the pace at which stations consume materials. The load per trip is small enough to carry easily. Standard work for the water spider defines exactly what happens at each stop. Deviations, a station running dry between visits, are signals that the cycle time or the load needs to be adjusted.
The water spider is the human embodiment of the milk run. In a factory built around one-piece flow, the water spider is what makes point-of-use storage sustainable, small quantities everywhere, always fresh, delivered on a rhythm the whole line can rely on.
A material management method in which all parts, components, tools, and documentation required for a specific product or operation are collected and organized into a single kit before production begins.
A scheduled transportation route collecting or delivering materials to multiple locations.
A visual signaling system that helps manage work and inventory by authorizing the production or movement of products.
