DFM Checklist for Product Design
Use this checklist before supplier quoting, prototype builds, tooling, or production release. It is designed for teams that need to catch manufacturing risk while changes are still cheap.
Start With Manufacturing Intent
A DFM review should not begin with isolated geometry rules. It should begin by asking what the part is supposed to do, how many units will be made, what process is planned, which dimensions are critical, what needs to look good, what can be flexible, and which supplier constraints are already known. The same product can require very different design choices for a one-off CNC prototype, a 50-unit pilot batch, or injection molding at production volume.
Before applying process-specific checks, define the target material, production volume, tolerance expectations, finish requirements, assembly sequence, inspection method, and cost drivers. A clear manufacturing intent prevents over-engineering where precision is unnecessary and under-engineering where precision is critical.
| Review Area | Questions to Ask |
|---|---|
| Function | What loads, temperature, vibration, fluids, impact, wear, or user interaction must the part survive? |
| Critical Dimensions | Which dimensions actually control fit, movement, sealing, alignment, inspection, or safety? |
| Material | Does the material match stiffness, toughness, temperature, chemical exposure, cosmetic, cost, and process requirements? |
| Supplier Handoff | Can a supplier quote the part from the CAD, drawing, material notes, finish notes, and quantity assumptions without guessing? |
Process-Specific DFM Checks
Each process has different failure modes. These checks are a starting point, not a substitute for supplier review.
Injection Molding
- Keep wall thickness as consistent as practical.
- Add draft on molded surfaces and ribs.
- Avoid unnecessary undercuts and side actions.
- Check ribs, bosses, snap fits, and screw posts for sink risk.
- Define cosmetic faces and likely parting-line sensitivity.
CNC Machining
- Confirm tool access to every machined feature.
- Avoid sharp internal corners that require special tooling.
- Reduce deep pockets, thin walls, and unnecessary tight tolerances.
- Consider setup count and datum strategy.
- Specify threads, surface finishes, and inspection points clearly.
Sheet Metal
- Use realistic bend radii and reliefs.
- Check flange lengths against tooling limits.
- Keep holes and cutouts away from bend zones.
- Plan hardware insertion, welds, and assembly access.
- Validate flat pattern and bend sequence.
Assembly and Documentation Checks
A manufacturable part can still fail as a product if the assembly sequence is awkward or the documentation leaves too much interpretation to the supplier. Review fastener access, tool clearance, part orientation, service access, datum references, cable routing, adhesives, inserts, seals, and any operations that depend on manual skill.
The final release package should include drawing revisions, material and finish notes, controlled tolerances, exploded assembly references when needed, BOM structure, accepted file formats, and open questions for the supplier. If a dimension is important, control it. If it is not important, avoid specifying it too tightly.
Need an engineer to apply this checklist to your CAD? Request a focused DFM review or send the current model through the project inquiry form.
Review Your CAD Before It Becomes Expensive
Send the design files, target process, material, quantity, and supplier constraints for a practical DFM review.
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