Original Date: 03/06/2006
Revision Date: / /
Information : Pull System
Raytheon Missile Systems’ Louisville facility has developed and implemented a pull system of manufacturing that lends itself to a remanufacturing environment. By concentrating on building product to a system execution plan and not a manufacturing resource requirement, Raytheon-Louisville has reduced work-in-process and improved schedule performance while increasing output.
Kanbans are a manufacturing control tool widely used by many organizations throughout industry. However, the pull system of manufacturing and the use of kanbans initiated by Raytheon Missile Systems’ Louisville facility are unique considering that a large part of the facility’s mission is the overhaul, repair, and remanufacture of highly complex weapons systems.
Prior to 2005, Raytheon-Louisville used the traditional manufacturing resource planning- (MRP-) driven push system to manage its production and workload planning. It was felt that this system was best suited to the facility’s operation due to the variability in the remanufacture and upgrade business. Under the former system, all work cells were managed to MRP dates regardless of consumption by the next process. This often resulted in overproduction at certain work cells (high inventories), non-optimization of labor hours, and much additional material handling when unused inventory was being sent to storage and later moved back to the production floor as needed.
Raytheon-Louisville underwent a major facility renovation and change in manufacturing philosophy in 2005 that justified a conversion to a pull system of manufacturing. As a facilitator to the pull system, Parts Presentation Vehicles (PPVs) were created and pull cards were introduced as kanbans. Work-in-process (WIP) units now move only to their point of use on Parts Presentation Vehicles (PPVs), with nothing going to inventory. The user of the WIP on the shop floor makes the kanban exchange, signaling the previous work cell to start production of the next unit of material.
Raytheon still uses an MRP system, not as a complete resource-planning tool but to load schedule on a macro basis. To drive the pull of the factory, a system execution plan is developed for each project. This plan is derived from a Raytheon-developed software program that concentrates only on major events. Drill-down menus give management and floor personnel the visibility of what needs to happen and when it needs to happen based on factory Takt times, not on MRP projections.
Since changing over to a pull system of manufacturing, Raytheon-Louisville has been able to realize the benefits of building only what is needed and when it is needed, reducing material handling of inventory, optimizing labor utilization, improving adherence to schedules, and reducing factory costs. They have shown that factory pull systems of manufacture can be accomplished in a remanufacturing environment. The company acknowledges the implementation of pull manufacturing as a significant factor in its overall cycle time reduction of 20%.
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