Original Date: 05/08/1995
Revision Date: 01/18/2007

McDonnell Douglas Aerospace (MDA)-St. Louis addressed the need for effective maintenance scheduling and machine monitoring that is critical to sustaining its high quality and complex machining capability. This was accomplished by developing a maintenance concept based on identification of critical equipment that comprise a Critical Path Equipment list, and by developing metrics to quantify the service quality of the Critical Path Equipment. These metrics are focused on the MTBF and breakdown response/repair cycle times. This effort will ensure that MDA-St. Louis continues to have a high speed machining (HSM) technology that provides alternative manufacturing processes accommodating new design alternatives for part designs.

This maintenance management concept employs a customized version of a commercial software package by the Electronic Data System Corporation called PERMAC. Using this software package (including its integration to other software packages to support the maintenance concept), Critical Path Equipment on the shop floor is tracked to ensure timely maintenance procedures for those pieces of equipment. The maintenance schedule is coordinated with the fabrication schedule to provide a harmonious transition between fabrication and required maintenance through PERMAC Computerized Maintenance Management. The Critical Path Equipment listing concept identifies critical machines that impact the fabrication process throughput for the machine center. This consequently raises the machine’s visibility to the shop floor user and management. Tracking of individual equipment is monitored by the Property Management System which is integrated with PERMAC.

With these capabilities integrated, PERMAC manages work order scheduled maintenance and installation/construction tasks. PERMAC can track individual property (equipment) numbers, labor cost, maintenance cycle time, and work order history.

With the PERMAC implementation, the maintenance concept has developed into a more robust capability of predictive/proactive maintenance for the shop floor with advanced diagnostics and testing tools. Critical Path Equipment is periodically tested for positioning to ensure proper machine alignment for operation. Integration of a vibration analysis tool estimates the requirement for maintenance for re-calibrating rotating equipment. Equipment sensors and on-line data acquisition will help assist in daily data gathering to depict the status of the system stored by PERMAC. With the historical data, predictive maintenance can then be carried out.

A major benefit achieved through this maintenance concept is increased throughput, or minimal mean time between failure for Critical Path Equipment. Scheduled repair time accounts for only a 4% loss of machine operation time since maintenance cycle times have been reduced. Also, this maintenance concept impacts the spare part procurement lead time estimates since minimal breakdown requires fewer replacement parts and consequently reduces inventory.

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