The eight categories of lean waste (TIMWOODS)
Lean thinking breaks waste into eight types so improvement efforts can be targeted. Transport (moving parts between stations or inventory locations) adds no value. Inventory (goods sitting in storage) ties up capital and risks obsolescence. Motion (reaching for tools, walking to get supplies) strains workers and slows cycles. Waiting (parts or people idle, approvals delayed) kills throughput. Overproduction (making more than needed) is the root of most other waste. Overprocessing (extra steps, inspections beyond spec, excessive documentation) complicates the flow. Defects (rework, scrap, quality escapes) consume resources with no value gain. Skills (underutilized talent, not listening to front-line ideas) leaves improvement on the table.
The acronym TIMWOODS helps teams scan the factory floor systematically. Every minute of a shift contains examples of all eight.
Prioritizing which waste to eliminate first
Attacking all eight simultaneously overwhelms a team. Wise organizations pick the biggest cost driver first. If inventory is tying up millions, start there. If rework is running 10% of output, fix defects. If motion accounts for 30% of cycle time, redesign the cell layout. This prioritization prevents the team from spinning on low-impact improvements.
The eight also create a shared vocabulary. When a manager and operator both understand 'overproduction' as filling a bin with more than the next station can use by shift end, they can spot and talk about the same waste. Consensus language accelerates consensus action.