Shop Floor Information Systems

Executive Summary:
Researchers developed prototype applications of computer technology for the modular factory floor. Research efforts focused on the collection of real time production labor data. While labor represents a relatively modest fraction of production cost, typically 10-15%, it has a profound impact on operations. Except for the slower winter months, experienced labor is a scarce resource. Even if labor is sufficient in the aggregate, it is rarely positioned where it is most needed at a particular moment in time. Competitive market pressures are resulting in an increasing mix of custom home features, increasing the likelihood of “floating bottlenecks” in production. Quality and safety can suffer as undermanned crews rush to complete custom features (i.e., fire-rated walls or a hip roof). If a crew cannot keep pace, the line slows, production rate drops, overtime is required and delivery dates are missed.

In the past, the sheer number of production activities, lengthy cycle times and extensive product customization have discouraged manufacturers from accurately estimating labor needs and using this information to plan and control production. Instead, they have responded by controlling labor at the overall plant level, attempting to maintain labor at a historical target value, which is stated as a percentage of overall production cost or sales revenue. A limitation of this approach is that it seldom reflects the actual labor content in the product, particularly in periods of increasing customization. To address the problem of shifting bottlenecks, many manufacturers use flexible resources termed “utility workers”, “flex workers”, or expeditors. However, the decision to deploy these workers is often made with minimal planning, after a problem has started to impact the line.

To better understand the true usage of production labor, the research team developed the Status Tracking and Control System (STACS). STACS is a real time labor data collection and reporting system designed specifically to meet the needs of the industrialized housing industry. Production workers use wireless laser scanners to report their current work assignment. Scanned information is transmitted immediately to a base station and then relayed to a local shop floor processor, where it is verified and temporarily staged. Information is periodically transmitted via wireless LAN to a central database server where it is stored and used for reporting. STACS reporting is web based and provides both real time manufacturing status and summaries of historical production performance. Real time production performance can be monitored from the web-based STACS Dashboard. “Clicking” on any item on the Dashboard will display corresponding real-time details. Historical results can be used for a variety of analytical and management purposes including: 1) the development of analytical labor estimating models (these models can be used to estimate labor requirements for product costing, production scheduling and labor planning) and 2) as a baseline for continuous improvement efforts.

An alpha prototype of STACS was tested in drywall finishing operations at Avis American Homes (Avis, PA) in Summer 2003. Test results demonstrated that production workers could operate the system effectively and that the system accurately captured scanned activity. Large scale plant-wide testing was performed at Penn Lyon Homes (Selinsgrove, PA) in Spring and Summer 2004. Test results were used to develop labor models using linear regression and neural nets. However, results indicated that workers were not conscientious in reporting work, that they received little encouragement or incentive from management to report work reliably, and that many other extraneous factors influenced work – such as delays from bottlenecks, material issues, quality/rework.
 

Technical Reports & Papers:
Mullens, M., “Data Collection and Predictive Modeling in Industrialized Housing,” Presented at IFORS 2005 Conference, Honolulu, July 2005.

Broadway, R. and M. Mullens, “Shop Floor Information Systems for Industrialized Housing Production,” Industrial Engineering Research ‘04 Conference Proceedings, Houston, May, 2004.

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