Assembly-aware concept evaluation in Modular Function Deployment, establishing an early-phase criteria subset and a selection routine

Abstract This paper tackled an emerging gap in modular product development: that Design for Assembly (DfA) is applied late in the product development process, after architectural choices are fixed, limiting the potential for scalability, improvements and late configuration. We aimed to establish a practical early-phase subset of assembly-oriented criteria and formalise a lightweight selection routine for Concept Evaluation (CE) within Modular Function Deployment (MFD). We conducted an exploratory survey and nine semi-structured interviews with industry practitioners. Survey ratings were analysed through descriptive statistics; interviews underwent reflexive thematic analysis. A relevance threshold with confirmation through interview of criterion estimability gave the subset. We then developed a selection routine combining market and assembly requirements to decide between technical solutions. The routine keeps both views and creates a standardised review plan. Results showed five criteria suitable for early CE: reduce assembly cost/complexity, ease of assembly, assembly automation opportunities, scalability opportunities, and late configuration. Two more criteria were kept as optional (limit production investment, limit production test cost); improved yield and assembly line balance were excluded. Limitations included a small sample and only descriptive analyses: findings were indicative. Future work will test impact on design outcomes, refine domain-specific criteria, integrate circularity indications for disassembly and recycling, and embed the routine in CE tools. Overall, the method makes assembly reasoning visible before the architecture is set, improving transparency and cross-functional alignment in modular concept selection.