iTSSe TSS A D V A N C E D M A T E R I A L S & P R O C E S S E S | J U L Y / A U G U S T 2 0 2 2 3 9 iTSSe TSS Thermal spray remains the process of choice for the application of protective and functional overlay surface treatments for gas turbine engine components to improve performance and extend serviceable life. Coating selection is an integral part of the design process and coatings can be selected for multiple reasons, including wear reduction, corrosion and oxidation protection, and prevention of oil and air leaks, especially in the flow path where leakage can harm overall performance. The performance and reliability of gas turbine engines depend greatly on the quality of the coatings within, and therefore manufacturing control of processes is of utmost importance to ensure that the resulting coating conforms to the full engineering definition. The cost of poor quality is considerable and as a percentage of sales can be as high as 15%, even for 5-sigma processes. The recent market challenges and post-pandemic recovery for aerospace will place a renewed emphasis on the drive toward a zero-defect culture within operations and the supply chain. The journey to zero defects can be a particular challenge for thermal spray and other special processes as quality cannot easily be measured in situ. A step change reduction in nonconformance and hidden waste can be achieved by using a disciplined approach to special process standardization and new technology introduction that incorporates: 1. Implementation of the right operating environment and culture 2. Quality procedures employing a system of standardized defect prevention tools 3. Digitalization through application of process sensors and diagnostics to assist in data-driven control solutions ACHIEVING ZERO DEFECTS IN THERMAL SPRAY: CULTURE, PROCEDURE AND DIGITALIZATION Developing a disciplined approach to standardizing special processes and introducing new technologies is key to eliminating defects in thermal spray applications. Ann Bolcavage, FASM,* and Benjamin Lagow, Rolls-Royce Corp., Indianapolis Goetz Feldmann, Rolls-Royce Deutschland Ltd & Co KG, Oberursel, Germany A CULTURE OF COMMITMENT The foundation for a zero-defect production culture starts at the thermal spray kit and surrounding shop area. Establishing an operating culture committed to process ownership, high functional standards, and a drive to continuously improve through root cause identification and corrective actions is not an engineering project but a leadership initiative. In other words, the organization must create an environment that is intolerant of nonconformance. A useful exercise to help put the right operating culture in place is to make a detailed walk of the process and assess the thermal spray cell infrastructure, equipment, and procedures (Fig. 1). Ideally, a collaborative audit should be carried out by a cross-functional team. An honest and evidence-based assessment of criteria incorporating people (training and resources), equipment (asset care, raw materials control), and environment (visual management, cleanliness) should be made against an acceptable minimum *Member of ASM International FEATURE Fig. 1 — Thermal spray cell, encompassing aspects of minimum standards for cleanliness, ergonomics, and layout. Courtesy of Turbine Surface Technologies Ltd. 5
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