Q: Can you apply OEE to a manual assembly line? We have established takt times for each of our manual assembly lines, and each assembly station has been balanced so that it can be completed within the required takt time helping us to have single piece flow. There are no machines involved in any of the assembly lines or processes, just assemblers and the tools they need to tighten screws and nuts or move larger/heavier parts onto the assembly line fixtures.
A: The quick answer is that applying OEE is possible but unnecessary—it’s overkill for a manually controlled process. I had several assembly plants over the years. Some made molded assemblies so the mold presses were the capacity constraint and were managed with OEE. In the case of balanced, manual-labor-only cells, I’ve seen two processes that work well.
- A simple way is to post a clipboard at the end of the line and manually keep track of pieces per hour actual vs. planned. The supervisor does hourly walk arounds to be sure all is well or intervenes if there are issues.
- My preferred way is to make the process visual with the use of andon lights. If the manufacturing cell is running on target, the light is green. If there’s been an interruption in the line to replace a broken fixture, for example, the light would be switched to yellow until corrected and back on takt time. If any part of the line balance causes a stoppage, then the light is turned to red. Ideally, the location of the supervisor’s office would have a line of sight to all andon lights. If that isn’t possible then I recommend use of andon lights that have audible alarms. It’s important to get the supervisor’s attention for immediate follow up if it’s not a quick fix by the operator.
Larry Fast is founder and president of Pathways to Manufacturing Excellence and a veteran of 35 years in the wire and cable industry. He is the author of The 12 Principles of Manufacturing Excellence, A Lean Leader's Guide to Achieving and Sustaining Excellence, 2nd. Edition.
