Olanrewaju, Oludolapo AkanniEzeani, Gregory Ifesinachi2026-06-092026-06-092024https://hdl.handle.net/10321/6378Submitted in fulfilment of the requirements for the degree of Doctor of Engineering: Industrial Engineering, Durban University of Technology, Durban, South Africa, 2024.As technology evolves globally, it becomes difficult for a single production improvement tool to support the maximum productivity, flexibility, and competitiveness necessary for a firm to continuously increase its value chain to fulfill customer-changing requirements. The global market of today continues to be more competitive and the demand for highly functional products, highquality service, shorter delivery lead-time, and environmental friendliness continues to grow to fit customers` changing demand requirements. This research focused on tackling the problem of underperformance of a firm`s products that cannot be properly covered by a single productivity improvement process such as lean or Agile. The unsatisfactory factor of using either lean or agile makes it difficult for a firm to continuously increase its productivity, flexibility, and competitiveness to support a firm ability to fit values that satisfy customer-changing requirements in both stable and turbulent market environments. The research study focused on the successful integration of lean and agile manufacturing processes in new product development to improve productivity, flexibility, and competitiveness to fit customer-changing requirements in a global market environment. Moreover, the effect of disturbances such as new entrants, technological evolution, globalization, and customerchanging requirements deprives a single tool such as lean or agile the ability to satisfy changing customer requirements. This effect of technological evolvement, globalization, etc., has led to redundancy, obsolescence, abandonment, and extinction which creates financial losses for firms. This research utilized synergies (robustness and smartification) of lean and agile tools to improve new products to fit customer-changing requirements in stable and turbulent market environments. The study used Taguchi's design of experiment to determine productivity differences in using a single tool of lean or single tool of agile or a combined tool of lean and agile in the management of new product development. The study performance outcome in terms of process performance (CP & CPK), Performance distribution, waste variation reduction, and loss function financial evaluation revealed that using a combination of lean and agile performed significantly best than using either a single tool of lean or a single tool of Agile. The study used the Taguchi design of the experiment to support a robust improvement integration process. The result showed that the integration of lean and agile methodology offers better efficiency and effectiveness than using either a single lean or agile methodology. The study concluded that using a combination of lean and agile tools improves the underperformance of new product development to fit customer market-changing requirements compared to using either a single lean tool or agile tool alone.124 penLean ManufacturingAgile ManufacturingLeagile ManufacturingNew Product Development (NPD)Product InnovationIndustrial EngineeringManufacturing FlexibilityProductivity ImprovementCompetitivenessProcess CapabilityProcess PerformanceContinuous ImprovementQuality ManagementTaguchi Design of ExperimentsRobust DesignWaste ReductionIndustry 4.0Manufacturing StrategyOperations ManagementProduct Development ManagementLean manufacturingManufacturing processesNew productsIndustrial productivity--Technological innovationsFlexible manufacturing systemsThesishttps://doi.org/10.51415/10321/6378