> ## Documentation Index
> Fetch the complete documentation index at: https://docs.cosmon.com/llms.txt
> Use this file to discover all available pages before exploring further.

# DFMA / Design Review

> Analyse designs for manufacturability and assembly, and run structured design reviews, without leaving your CAD tool.

## Overview

DFMA (Design for Manufacturing and Assembly) and design review are both about finding problems before the design is locked — DFMA by checking geometry against manufacturing and assembly constraints, design review by checking the design against requirements, standards, and the judgment of other engineers.

Nexus runs both directly on your CAD models: it flags problem areas, explains why they're a problem, and can apply the fix. It can also prepare and run the review itself — comparing revisions, checking against a requirement set, and producing a findings list for the meeting. What normally takes hours of manual review can be done in a single prompt.

## DFMA

The most common DFMA variants:

* **DfM** — Design for Manufacturability
* **DfA** — Design for Assembly
* **DfS** — Design for Sustainability
* **DfR** — Design for Reliability

### What Nexus can help with

* **DfM** — Identify features that will be difficult or expensive to manufacture: undercuts, thin walls, sharp internal corners, non-standard tool sizes, insufficient draft angles.
* **DfA** — Flag components that are hard to access during assembly, have no clear insertion direction, or require special tooling.
* **DfS** — Estimate material usage, identify overbuilt sections that can be lightweighted, and flag high embodied-carbon materials.
* **DfR** — Identify stress concentrations, fatigue-prone geometry, and features likely to fail under repeated loading.

### Example prompts

<AccordionGroup>
  <Accordion icon="industry" title="DfM — Check for CNC machineability">
    ```text theme={null}
    Analyse the active part for CNC machineability. Flag any undercuts, wall thickness below 1.5mm, and internal corner radii smaller than R3. List each issue with its location and a suggested fix.
    ```
  </Accordion>

  <Accordion icon="industry" title="DfM — Injection moulding check">
    ```text theme={null}
    Check the current part for injection moulding issues. The draw direction is +Z. Flag any undercuts, draft angles below 1°, wall thickness outside 2–4mm, and sink risk areas. Prioritise by severity.
    ```
  </Accordion>

  <Accordion icon="screwdriver-wrench" title="DfA — Assembly review">
    ```text theme={null}
    Review the assembly at C:/Projects/Pump_Housing/pump_asm_v2.SLDASM for assembly difficulty. Identify any components that cannot be inserted without first removing another part, and list them in order of severity.
    ```
  </Accordion>

  <Accordion icon="leaf" title="DfS — Lightweighting">
    ```text theme={null}
    Identify regions in the bracket where material can be removed without significantly reducing stiffness. Suggest topology changes and estimate the mass reduction for each.
    ```
  </Accordion>

  <Accordion icon="rotate" title="DfR — Fatigue-prone geometry">
    ```text theme={null}
    Review the weldment for fatigue risk under cyclic loading (10^6 cycles, load reverses through zero). Flag sharp re-entrant corners, sudden section changes, and unsupported cantilevered features. Suggest geometry changes to reduce stress concentration at each.
    ```
  </Accordion>
</AccordionGroup>

## Design review

A design review checks the model against requirements, standards, and previous decisions — not just manufacturability. Nexus can prepare the review package, run the requirement checks, and diff revisions so the meeting starts with a findings list instead of a blank model.

### What Nexus can help with

* **Requirement compliance** — Check the model against a written requirement set and list every feature that doesn't comply.
* **Revision comparison** — Diff two versions of a part or assembly and summarise what changed: geometry, mass, dimensions, custom properties.
* **Review packages** — Generate the summary document a review board expects: overview, open questions, DFMA findings, and requirement compliance in one place.
* **Open-question tracking** — Surface areas of the design that are ambiguous, underspecified, or depend on an assumption that hasn't been confirmed.

### Example prompts

<AccordionGroup>
  <Accordion icon="clipboard-check" title="Compliance review against requirements">
    ```text theme={null}
    Review this part against the following requirements: max weight 250g, material PA66-GF30, wall thickness 2.5–4mm, no undercuts, all radii ≥ R2. List every feature that does not comply and explain why.
    ```
  </Accordion>

  <Accordion icon="code-compare" title="Compare two revisions">
    ```text theme={null}
    Compare C:/Projects/Bracket/bracket_rev_a.SLDPRT against C:/Projects/Bracket/bracket_rev_b.SLDPRT. List every dimensional change, any features added or removed, and the resulting change in mass. Flag anything that would affect the mating clearance plate.
    ```
  </Accordion>

  <Accordion icon="file-lines" title="Generate a design review package">
    ```text theme={null}
    Prepare a design review package for the pump housing assembly: a one-page summary of the design intent, the DfM and DfA findings from this session, a list of open questions, and a compliance check against the attached requirements document. Format it for a PDF handout.
    ```
  </Accordion>

  <Accordion icon="circle-question" title="Surface open questions">
    ```text theme={null}
    Go through this assembly and list anything that looks underspecified or assumption-driven — missing tolerances, generic materials, mates that don't reflect a real fastening method, or features with no clear function. I'm prepping for design review and want the gaps, not a pass/fail.
    ```
  </Accordion>
</AccordionGroup>

## Tips for DFMA and design review prompts

* **Name the process** — The rules for CNC differ from injection moulding, casting, or 3D printing. Always state the manufacturing process so Nexus applies the right checks.
* **Specify standards** — Include tolerancing standards (ISO 2768, GD\&T) or internal guidelines if relevant.
* **Attach the requirements document** — For compliance reviews, attach the actual spec rather than restating it from memory — Nexus checks against what's written, not what's implied.
* **Ask for a prioritised list** — Nexus can rank issues by severity, cost impact, or ease of fix.
* **Apply the fixes** — After reviewing the list, prompt "apply the highest-priority fixes" and Nexus will make the geometry changes directly.
* **State what changed, not just what to compare** — When diffing revisions, mention any context (a customer request, a failed test) so Nexus can flag whether the change actually addresses it.