Design review

A design review is a planned, systematic and documented evaluation of a product design at a defined development milestone. A team made up of the design's authors and people who did not work on it directly checks whether the solution meets the requirements, which risks remain and whether the project can move on to the next phase. The output is a decision and a list of action items with owners and due dates, not just a presentation.

Development usually includes reviews at several levels: a conceptual design review (choice of working principle and architecture), a preliminary design review or PDR (design in progress, calculations and first prototypes), a critical design review or CDR (design ready for tooling to be ordered) and a review before release to series production. Between milestones, smaller specialist checks take place, such as drawing checks, a manufacturability review with the supplier or the evaluation of test results.

The inputs are the product requirements specification, current CAD models and drawings, calculations such as finite element analysis (FEA) and tolerance analysis, the FMEA, prototype testing results, a cost estimate and a list of open issues. The review assesses whether the requirements are met, manufacturability and ease of assembly, safety, serviceability, cost against target and regulatory compliance.

A design review is not the same as verification and validation. Verification demonstrates by calculation, measurement or testing that the design meets the specified requirements, while validation confirms that the product serves the user in its intended use. A design review evaluates the state of the design as a whole and draws on the results of both. A quality management system to ISO 9001 requires all three activities in design and development, along with retained records of them.

Schedule a design review at every milestone that is followed by an expensive or hard-to-reverse decision: selecting the concept, ordering prototypes made with costly processes, ordering molds and tooling, and release to series production. A formal review pays off even in a small team or for a single designer, because an independent view catches mistakes the author overlooks.

In contract development, a review with the customer is a good moment to agree on the current status and freeze the requirements. Scale the effort to the risk: for a simple part, a checklist and a short meeting are enough, while an assembly with a safety function, or a project about to order an expensive mold, calls for a detailed review with manufacturing engineering, quality and purchasing.

The most common mistake is a review that turns into a presentation with no decision. Send the materials to participants in advance, review against a checklist, and at the end record the outcome (proceed, proceed with conditions, rework) together with a list of findings, each with an owner and a due date. Track open items until they are closed, or they will resurface at the next review.

Another mistake is inviting only the design's authors, or putting the review off until the mold has been ordered and changes are expensive. Invite people from manufacturing, assembly, quality, purchasing and service, who see risks the design engineer does not. Make sure the current revision of the models and drawings is being reviewed and that the record states which revisions were reviewed.