Inselmann, PascalPascalInselmannWehrend, SvenSvenWehrendKrause, DieterDieterKrause2026-01-062026-01-062025-0936th Symposium Design for X, DFX 2025https://hdl.handle.net/11420/60446Interfaces play a central role in modular product families, influencing both modularity and cost efficiency. However, their strategic importance throughout the product lifecycle is often underestimated, as the requirements vary largely between different life phases. This paper introduces a systematic approach to identifying, classifying and evaluating interfaces, based on criteria such as functionality, variety, communication effort, lifecycle connection and costs. This approach allows for a relevance ranking and supports targeted standardization or integration strategies. Applying this approach to a robot vacuum product family reveals critical interfaces and related trade-offs, helping to improve product family architectures at an early stage.enhttps://creativecommons.org/licenses/by/4.0/Product DevelopmentInterface DesignLifecycle AnalysisTechnology::658: General Managament::658.5: Of ProductionConference Paperhttps://doi.org/10.15480/882.1635310.35199/dfx2025.2410.15480/882.16353Conference Paper