The Traffic Cop - Root Cause Analysis

Such a large drop in tool utilization on the 5xStep tool group leads the Traffic Cop to look more closely at the tool states in this group. The chart below shows SEMI E-10 states, averaged across the six 5x Steppers. The red unscheduled downtime bar is clearly larger for the night shift of May 23rd (when the problem with WIP turns and moves began). 

A closer look at the states of each tool during the night shift on May 23rd is shown below. The Traffic Cop observes that three of the six tools in the group had NO productive time at all during the shift. A fourth tool in the group spent more than 15 of its time idle - despite the overall WIP building in the area. 

The reduced capacity of the 5xStep tool group clearly contributes to the overall problems with inventory age and WIP turns in the factory. The Traffic Cop takes the analysis one step further, by looking at the impact on cycle time. (Continue to the next page.)