Work in Process (WIP) represents the materials and partially completed products on the shop floor at any given time. It includes raw material that has been issued to a work order, parts in the middle of machining or assembly operations, and semi-finished goods waiting in queue between operations. WIP ties up capital and occupies floor space, making it a key metric for manufacturing efficiency.
Excess WIP is a symptom of underlying problems: long setup times that encourage large batch sizes, unreliable processes that require buffer stock, poor scheduling that creates bottleneck queues, and long lead times on purchased components that force early release of work orders. Lean manufacturing specifically targets WIP reduction as a way to expose and address these root causes.
Tracking WIP accurately requires knowing the location and status of every job on the floor. In shops that rely on paper travelers or whiteboards, WIP visibility is always outdated. Digital work order tracking with operation-level status updates provides real-time WIP visibility, enabling better scheduling decisions and shorter lead times through reduced queue time.