The Customer: Sandia is
implementing a real-time predictive maintenance system (WinR-PdM) on the production floor at AlliedSignal/Federal Manufacturing and Technology, AS/FM&T. Specifically, the system will be installed on
AS/FM&T's Flexible Manufacturing System (FMS). As part of that effort, detailed reliability analysis studies have been performed on the 6 milling machines that make up the FMS. The purpose of these
studies was to better understand the reliability of the machines and to identify failure modes that are key contributors to unreliability.
The Work:
Maintenance records were supplied by Allied Signal covering the time period from
12/15/93 to about 6/3/97. These records covered some 940 failure events for the 6 milling machines. These failure records were analyzed using Sandia's WinR-DP software. Figure 1 shows a bar chart of mean
time between failures by machine.
Figure 1. MTBF for Milling Machines in FMS For the machine with the lowest MTBF (Orion M1), Figure 2 shows the top failure modes. 
Figure 2. Top Failure Modes for Orion M2
Key Benefits:
- Understanding of machine tool reliability and problem areas was greatly improved, and
- Predictive and preventive maintenance activities were better targeted to improve equipment productivity.
Results:
- Key reliability measures including MTBF, availability, and down time were quantified for all 6 milling machines.
- Top failure mode contributors to MTBF, unavailability, and down time were identified, and
- Causes of machine-to-machine variability were defined.
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