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A CAD design is manufacturable only in relation to a particular process, material, production volume, tolerance plan, tooling approach, and quality target. The practical way to assess it is to define those conditions, screen the geometry against process-specific constraints, then ask the intended manufacturer to resolve open issues before you commit to tooling or production.
Define what “manufacturable” means for this part
The same geometry may be straightforward to machine but difficult or costly to mold, form, or produce by another method. Start by writing down the assumptions behind the design review; a checklist or automated scan is meaningful only when it is tied to an actual process and production context.
- Process: Identify the likely process or processes, such as CNC machining, injection molding, or sheet-metal fabrication.
- Material: Name the intended material and any performance requirements that rule out alternatives.
- Production volume: State the expected quantity. Tooling and setup burdens can change the relative practicality of process options.
- Critical dimensions and tolerances: Mark which dimensions affect fit, function, or interchangeability. Avoid imposing tight tolerances on noncritical features without a reason.
- Surface finish: Specify finish requirements only where appearance, sealing, friction, or another functional need calls for them.
- Acceptance and inspection: Explain how the part will be judged and which characteristics must be verified.
DFM, or design for manufacturing, considers process, material, geometry, tolerances, tooling, volume, and quality together—not geometry alone. Boothroyd Dewhurst outlines that scope in its DFM principles and checklist.
Screen the geometry against the chosen process
Use process-specific checks as early warning prompts, not universal pass/fail rules. Supplier equipment, material, part size, and functional requirements can change what is feasible.
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CNC machining
- Check whether cutters can reach every surface that needs machining, including deep pockets and internal features.
- Review internal corner radii and pocket proportions against available tooling. Boothroyd Dewhurst gives an internal-corner-radius rule of thumb of at least three times the depth to allow standard end mills; validate that guidance with the selected tool, material, and supplier.
- Consider how many setups and how much fixturing the part needs. Features that require awkward access or repeated repositioning may add cost or risk.
- Review tolerance and surface-finish callouts against function, as well as material availability and inspection needs.
Injection molding
- Look for consistent wall thickness, draft, undercuts, ribs, gate placement, and a way to eject the part.
- Boothroyd Dewhurst’s checklist uses uniform wall thickness within a ±10% variation target and draft angles of at least 1 degree as rules of thumb. It also describes 1–2 degrees of draft per side as typical. These are screening values, not specifications that fit every resin, geometry, tool, or supplier.
- Ask how the selected pull direction affects features and whether undercuts require additional tooling or another design change.
Sheet metal
- Check bend radii against the material and stock gauge, and confirm holes and cutouts have workable spacing from bends and edges.
- Boothroyd Dewhurst gives bend radii of at least the material thickness and hole-to-edge spacing of at least twice the material thickness as rules of thumb. Confirm both with the chosen material, thickness, tooling, and fabricator.
- Review the flat pattern, nesting, and bend sequence, not just the finished three-dimensional shape.
For a broader screening pass, Boothroyd Dewhurst offers a DFM design review checklist covering CNC machining, injection molding, sheet metal, die casting, forging, investment casting, extrusion, and PCB. A separate CNC pre-submission checklist is framed around reviewing machined parts before requesting quotes.
Compare process options using the same assumptions
If more than one process may work, compare them against the part’s actual requirements rather than treating one DFM result as transferable to another. Record the assumptions so the comparison can be reviewed by a manufacturer.
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- Expected production volume
- Material and performance requirements
- Feature accessibility and geometry
- Required tolerances and finish
- Tooling and secondary-operation burden
- Inspection requirements
- Supplier capability for the process and part
Tight tolerances or elaborate finishes can call for additional operations, so tie each requirement to a functional need. A design that screens well for one process may still need substantial changes for another.
Use CAD analysis for scoped checks, not certification
Automated design feedback can help surface process-specific concerns, but it cannot establish that a part is manufacturable under every process or supplier’s conditions. Autodesk Fusion’s Design Advice feature checks injection-molding concerns for a selected solid body and pull direction, using plastic rules associated with the component or a default rule. Autodesk documents it as part of Fusion’s Design Extension; check current availability and licensing in the Fusion Design Advice documentation.
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Interpret a scan as a targeted review of the selected assumptions and rules. It does not replace checks for other processes, supplier-specific tooling, inspection plans, or functional requirements.
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Before making tooling or production commitments, send the intended supplier the authoritative CAD model and the information needed to assess it: relevant drawings and specifications, material, tolerances, production context, and quality expectations. Ask the supplier to identify assumptions, process-specific risks, and open questions in the review.
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- Choose the process and supplier context the review should address.
- Provide the current, authoritative CAD model along with the relevant drawing and specifications.
- State material, expected volume, critical tolerances, finish requirements, and acceptance criteria.
- Ask the supplier to call out geometry or requirements that may need a design change, extra operation, special tooling, or further clarification.
- Resolve open issues and update the design and documentation before approving tooling or production.
For a deeper treatment of the discipline, Boothroyd Dewhurst identifies Product Design for Manufacture and Assembly by Boothroyd, Dewhurst, and Knight as a commercial textbook in its DFMA resources.
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