Quality Magazine

Giving Eyes to a Manufacturing Facility with an Indoor Location System

July 25, 2011

Any manufacturing process is a network of interrelated motion, with raw material and subassemblies moving through carefully orchestrated steps to emerge as high quality finished goods. A manufacturing facility is a machine of many moving parts, all of which must stay synchronized in order to maintain peak efficiency. The question is: how does one manage and control so many moving parts when one doesn’t know where everything is?

Indoor location systems are providing that insight to many manufacturers today in diverse industries. There are three layers of value that a location system can bring at different levels of integration with operations. These range from providing oversight of important assets; to measuring progress against plan; to actually interfacing with tools for error proofing and quality control.

At the highest level, companies are using location-based asset managers to keep track of tools, work in progress and work orders throughout their facilities. These solutions present search queries on map displays for instant location of critical assets. Even this basic level of functionality can save many cumulative man-hours of searching for lost or misplaced items. Typically these solutions are able to integrate multiple location technologies in order to provide very precise information where necessary, approximate location when adequate and, increasingly, GPS tracking for very large sites with significant outdoor work areas. As an example, Cummins has all but eliminated search time for engines in offline storage areas, whereas previous searches for a given red engine in a sea of red engines wasted many hours per day.

Eurocopter in France is an example of a company leveraging the additional reporting and alerting functionality of asset managers. By collecting data over a period of time these solutions can identify process bottlenecks, rarely used tools, and other inefficiencies not visible without ongoing oversight of where things are and how they are moving. This automated process-discovery is a critical part of any continuous improvement activity. Additionally, real time alerts can help ensure that assets are not mistakenly removed from designated areas, or work-in-progress (WIP) stalled for longer than a given period.

This last benefit leads into the second level of value that a location system brings: by integrating information about the production process, location solutions can report progress against plan. Eurocopter’s sister company Airbus has deployed a location system through multiple sites which is doing just that. Aircraft subassemblies are tracked through the production and assembly facilities in multiple countries. Since the location system has been programmed to understand where, for example, wing skinning occurs or where the aft fuselage is attached, it can translate “where in the building” to “where in the process.” This level of integration provides not only a more detailed level of historical reporting supporting continuous improvement initiatives, but it also raises real time alerts when delays can cause a ripple effect through processes spanning months and continents.

Aston Martin uses a similar system in the United Kingdom to monitor and manage operations in the off-line finishing area. Aston Martin manufactures vehicles in relatively low volumes and each vehicle is highly bespoke. This mirrors the aerospace industry in terms of managing many variations of a single design in a relatively low throughput, long duration operation. At the other end of the scale auto manufacturers such as BMW are shaving precious seconds off high-volume operations and simultaneously improving quality.

The benefits enjoyed at BMW come from the third layer of location system value when location information is integrated directly with operations on the line. Here locations systems truly create smart environments that untether operations from the constraints of the physical production line.

In the case of BMW, a location system is used to track vehicles and cordless nutrunners in order to perform highly reliable tool/VIN matching with no manual intervention or delays. Like most manufacturers, BMW mixes model and trim types on a single line, but in the case of 1- and 3-series lines this is taken to an extreme. On these lines a very large number of vehicle variations are assembled in the order in which they are to ship. With this kind of variability it is critical to ensure that a cordless tool with a given torque setting operates on the correct vehicle. A location system is used to enable and disable tools depending on the correct tool/torque/vehicle matching with reliability exceeding six-sigma. This ensures that critical joints are correctly tightened, and saves six seconds over manual error-proofing processes at 150 steps across 1,000 vehicles per day.

The true value of using location systems in this way comes from the fact that this kind of error-proofing is enabled by location systems that flood assembly areas with location awareness. This is a marked contrast from traditional systems of identification and location which rely on devices fixed to the line in carefully chosen locations. In order to keep track of vehicles and tools traditional “spot check” methods use devices ranging from barcode readers and physical limit switches to tool tethers and articulated arms.

By decoupling vehicle and tool ID and tracking from these fixed devices, location systems add a new level of flexibility to assembly processes. Rather than physically fixed work cells, the concept of a work cell becomes a software defined zone which can be attached to a physical location or to a particular vehicle, and which can be reconfigured through software. Two very important flexibilities are introduced in this way. First, tools can now roam out of fixed work cells with no compromise in error proofing or quality control. Second, reconfiguring and rebalancing the line is significantly improved when tool control zones can be defined quickly and simply in software.

Indoor location systems are giving manufacturing facilities eyes, opening up a broad set of use cases proven to save time and improve quality. From asset accountability to WIP tracking, from automatic monitoring of progress against plan to flexible, untethered tool control, location systems are ushering in a new way of thinking about manufacturing operations.