Lead time modeling and acceleration of product design and development

New product development is an important business process and constitutes a major contributor to the business excellence of any manufacturing firm. Designing an optimized new product development process is an important problem in itself and is of significant practical and research interest. Lead time is an important performance metric for a product development organization. In this paper, we develop lead time models for product development organizations that involve multiple, concurrent projects with contention for human/technical resources. The objective is to explore how the lead times can be reduced using efficient scheduling, input control, load balancing, and variability reduction. The models are based on single class and multiclass queueing networks and capture important facets of a product development organization, such as: concurrent execution of multiple projects, contention for resources, feedback and reworking of project tasks, and variability of new project initiations and task execution times. Within the new product development process, we focus attention on the product design process, which is an important subprocess. Two product design organizations, which we call Company ABC and Company XYZ, provide the real-world setting for our model-based lead time reduction. First, we present a coarse, conceptual queueing network model of Company ABC and show how rapid performance analysis can be used to explore opportunities for accelerating the design process. In particular, we show how effective input control, process control, load balancing, and cross-functional work can cut the lead times. Next, we present multiclass queueing network models (re-entrant lines) for both the companies ABC and XYZ. The re-entrant line models show up certain scheduling issues pertaining to internal flows in the product design network. Using a class of fluctuation smoothing scheduling policies, we demonstrate how lead times can be reduced appreciably, without committing additional resources. The models presented are sufficiently generic and conceptual, and will be of much value in project planning and management in product design organizations and also more generally in product development organizations.