Spaghetti Diagram
A spaghetti diagram is a Lean process-analysis tool that traces the actual movement of people, materials, products, or information onto a facility layout. By drawing real routes through picking, receiving, kitting, staging, or workstation sequences, it exposes backtracking, crossings, loops, and excessive travel distance, helping teams redesign flow based on observed behavior rather than intended process maps.
On the shop floor, a supervisor or industrial engineer selects a process boundary—such as raw material receiving through line-side replenishment—and observes forklifts, pallet jacks, operators, or cartons in real time. The actual route is drawn onto a scaled layout with continuous lines, revealing repeated aisle traversals, long detours, and return trips. In production, this shows material handoffs between workstations and inspection points, exposing transport and motion waste that inflate cycle time. In warehousing, it shortens walking paths for picking, putaway, and shipping while reducing dock and staging congestion. For raw material tracking, it exposes avoidable touches and delays between quarantine, inspection, bulk storage, supermarket locations, and point-of-use. The technical value is that distance and path observations justify layout changes, slotting adjustments, or process re-sequencing with data, turning assumptions about inefficiency into measurable redesign priorities.
What data should be captured to make a spaghetti diagram operationally useful?
Process start/stop points, sequence of steps, actual path taken, distances traveled, waiting time, number of touches, and the physical layout of the area.
What Lean waste does a spaghetti diagram primarily expose?
Motion and transportation waste, plus secondary effects such as congestion, rehandling, and non-value-added walking or vehicle movement.
Where does a spaghetti diagram fit relative to value stream mapping?
Value stream mapping shows information and material flow across the broader end-to-end process, while a spaghetti diagram is a more granular physical-flow tool used to diagnose layout and movement inefficiency within a specific area.