Design Guide
What Is Design for Manufacturing?
Design for Manufacturing (DFM) is the practice of designing a part so it can be produced reliably, quickly, and at the lowest reasonable cost — without sacrificing fit or function. Applying DFM principles before a design is finalized almost always saves more time and money than fixing manufacturability problems after tooling or production has already started.
Basic DFM Principles
1
Simplify Geometry
Reduce the number of features, separate parts, and unnecessary complexity. Every added feature is another opportunity for cost, tooling complexity, or failure. The best part, is no part!
2
Keep Wall Thickness Consistent
Avoid abrupt thick-to-thin transitions. Uneven walls cause warping, sink marks, and internal stress in both molded and printed parts.
3
Design for the Process You'll Use
Tolerances, minimum feature size, and achievable geometry vary by process. A design that's easy to injection mold may be difficult to CNC, and vice versa.
4
Plan for Support Structures
In additive manufacturing, avoid steep unsupported overhangs where possible, or orient the part to minimize supports and post-processing. Part orientatio matters!
5
Add Draft Angles
Vertical walls on molded or cast parts need a slight taper — typically 1–2° — so the part releases cleanly from the tool.
6
Use Generous Fillets and Radii
Sharp internal corners concentrate stress and are harder to produce cleanly. Rounded transitions improve both strength and manufacturability.
7
Standardize Features and Hardware
Reuse common hole sizes, thread standards, and fasteners across a design to reduce tooling variation and inventory overhead.
8
Specify Only the Tolerances You Need
Tight tolerances add cost and lead time. Reserve them for the surfaces and features where fit or function actually requires precision.
Key Considerations for Manufacturability
- ✓Material selection — mechanical properties, thermal performance, chemical resistance, and cost all depend on material choice, and not every material works with every process.
- ✓Production volume — a design that's economical as a one-off prototype may not be economical at scale, and vice versa. Volume should help drive process selection.
- ✓Tolerances and fits — define critical dimensions clearly, and leave everything else loose. Over-specifying tolerances is one of the most common, and most avoidable, sources of added cost.
- ✓Surface finish — as-printed, as-molded, and as-machined finishes vary widely; specify only the finish your application actually needs.
- ✓Assembly strategy — plan how parts will be joined — snap-fits, threaded inserts, fasteners, or adhesives — as part of the design, not as an afterthought.
- ✓Cost vs. lead time — the fastest turnaround often means a different process or material than the lowest-cost option; decide which matters more for a given part.
- ✓Testing and validation — build in time to test form, fit, and function early, while changes are still inexpensive to make.
Process-Specific Quick Tips
- Keep unsupported overhangs under roughly 45° where possible.
- Avoid very thin walls (under ~1mm) for adequate strength.
- Round or chamfer sharp edges to reduce layer-line stress risers.
- Hollow large solid volumes and add drain holes to save resin and reduce cure stress.
- Avoid trapped volumes that can't be drained or cleaned.
- Take advantage of fine features and tight tolerances where precision matters.
- Prioritize iteration speed — design for fast form, fit, and function testing, not final production.
- Break complex assemblies into modular, testable sections so a single feature can be revised without reprinting the whole part.
- Match material and process to what you're validating; a rough form-check doesn't need the same rigor as a load-bearing test.
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