Availability modeling for the application of manufacturing equipment

In this paper, the author shows that two significant areas of manufacturing availability are not addressed with traditional reliability modeling. First, manufacturing goals-quality parts at the required production rate-can be met despite the "fact" that the system did not meet its uptime requirements. Second, process failures can contribute more to manufacturing downtime than actual hardware failures. Proper modeling of manufacturing systems to include all sources of downtime, whether hardware, software, human, or process as well as the production rates, will provide a more accurate depiction of operation. Methods have been developed by others to model software and human reliability. The approach paper details a model for including process reliability and production capacity. The resultant analysis provides a method to help assure that reliability improvement efforts are focused on the primary root causes of downtime-in many cases process problems and not more costly and sometimes technologically infeasible hardware improvement. The analysis also points to addressing the production capabilities so that the operational goal for the manufacturing equipment is not missed.