What is a manufacturing execution system?
A manufacturing execution system (MES) runs production between the plan and the finished part. It holds how each part is made, schedules jobs onto workstations within their shifts, and records what really happened on the floor: who worked each stage, for how long, how many good and rejected pieces came off, and why work stopped.
In most plants the schedule lives on a whiteboard or in one planner's spreadsheet. A rush order goes in, three other jobs quietly slip, and nobody knows until dispatch asks where the parts are. Output is written on job cards that reach the office a day later, so downtime and rejects never get counted properly.