Case Study 71: The Case Of The Variable Laminates 2006

Case Study 71the Case Of The Variable Laminates 2006 Victor E Sow

CASE STUDY 7.1: The Case of the Variable Laminates ©2006 Victor E. Sower, Ph.D., C.Q.E. A plywood manufacturer faces a significant challenge in controlling the thickness of laminates produced during the log-peeling process. This process involves soaking logs in hot water, fixing them in chucks, and rapidly spinning them while shaving off a thin laminate sheet. Variability in the final product’s thickness can adversely affect product quality, manufacturing efficiency, and material yield. To address these issues, a systematic experimental approach is required to identify and control the key variables influencing laminate thickness.

Designing an Experiment to Identify Influential Variables in Laminate Thickness

Effective process improvement begins with understanding which variables significantly affect the output—in this case, laminate thickness. Based on the case, the four variables identified as potentially influencing thickness are soak time, soak temperature, knife pressure, and knife setting. Since the knife setting is not deemed a significant source of variation, focus will be placed on soak time, soak temperature, and knife pressure. A factorial experiment design is appropriate here because it facilitates the study of multiple factors simultaneously and allows for interaction effects to be examined.

The recommended experimental framework is a full factorial design with two levels for each factor:

• Soak time: Short (30 minutes) and long (60 minutes)
• Soak temperature: Low (150°C) and high (200°C)
• Knife pressure: Low (250 psi) and high (300 psi)

This 2x2x2 factorial design involves conducting experiments under all eight possible combinations of these factor levels. Each experiment should be replicated at least three times to obtain reliable data and enable statistical analysis. The responses—laminate thickness—will be measured at regular intervals, such as every 15 minutes, to observe the effects over the peeling period.

Data Collection and Analysis

The collected data will be subjected to analysis of variance (ANOVA) to determine which factors significantly affect laminate thickness and whether interaction effects exist between factors. For example, it is possible that soak temperature and soak time interact to influence thickness. The results will provide insights into the relative importance of each variable and guide process modifications.

Assessment of Organizational Practices and Recommendations for Standardization

The current organization exhibits a lack of standardization, particularly in soak time, temperature, and knife pressure. Operators are adjusting these variables based on experience rather than standardized procedures, leading to inconsistent product quality. The concept of “repeatable work” pertains to performing the same tasks in a uniform manner, yielding predictable and controllable results. An organization that values repeatability fosters a stable process, essential for continuous improvement activities. Inconsistent practices hinder the ability to identify process deviations and reduce variability effectively.

To enhance repeatability and improve process control, the organization should implement standardized procedures for all critical variables identified through the experiment. These include:

• Establishing a fixed soak time at 60 minutes, aligning with the specifications and experimental evidence indicating this duration optimizes conditions.
• Standardizing soak temperature, perhaps at an optimal level identified through experimentation (e.g., 180°C), to ensure consistent heating conditions.
• Developing a formalized protocol for knife pressure, possibly fixing it at a midpoint value (e.g., 275 psi), and installing pressure regulators or gauges to maintain it within a tight tolerance.

Training operators to follow these standardized procedures is critical, along with implementing checks and controls to monitor adherence. Furthermore, adopting statistical process control (SPC) charts can enable real-time monitoring of laminate thickness and early detection of deviations from the target.

The Role of Repeatable Work in Continuous Improvement

Repeatable work creates a foundation for continuous improvement by reducing process variability and enabling accurate measurement of process performance over time. When processes are repeatable, any changes made can be reliably assessed for their impact, facilitating data-driven decision-making. Without repeatability, process variability masks the effects of improvements, making optimization efforts ineffective and potentially leading to unnecessary adjustments or corrections.

In the context of the plywood manufacturing process discussed, establishing repeatability means consistently controlling soak times, temperatures, and knife pressures to produce laminates within desired thickness ranges. This consistency provides a stable baseline from which incremental improvements can be made, such as refining process settings or implementing new technologies. It also enhances product quality, reduces waste, and increases customer satisfaction, ultimately contributing to a more competitive manufacturing operation.

Conclusion

Addressing laminate thickness variability requires a systematic approach involving designed experiments to identify key contributing variables, followed by organizational efforts to standardize processes. Employing factorial experiments enables the process engineers to pinpoint critical factors and their interactions, thus guiding targeted process controls. Establishing standardized work procedures promotes repeatability, empowering the organization to execute continuous improvement initiatives confidently. Ultimately,ing a focus on repeatability ensures consistent product quality, operational efficiency, and sustained competitive advantage in the manufacturing environment.

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