Design for manufacturability (DFM) is the process of optimizing a plastic part design so it can be molded reliably and cost-effectively. A good DFM review catches problems before steel is cut, saving time and money. Here is a practical checklist for injection molded parts.
1. Wall Thickness
- Keep wall thickness uniform to avoid sink marks and warpage
- Avoid abrupt thickness changes; use gradual transitions
- Stay within recommended thickness for the selected material
2. Draft Angles
- Add draft to vertical walls so the part ejects cleanly
- Typical draft is 0.5 to 2 degrees, more for textured surfaces
- Ensure draft direction is consistent with the parting line
3. Ribs and Bosses
- Keep rib thickness at 40-60% of the wall thickness
- Use proper boss design for screw or insert retention
- Add radii at rib and boss bases to reduce stress
4. Gate Location
- Place gates to balance filling and avoid visible flow lines
- Consider gate type based on part appearance and function
- Review weld line location for cosmetic and strength impact
5. Undercuts and Slides
- Minimize undercuts where possible to simplify tooling
- When needed, plan slides or lifters and their travel
- Confirm draft and shutoff angles for moving actions
6. Surface Finish and Texture
- Specify finish and texture early; texture needs extra draft
- Consider parting line location for appearance parts
- Confirm polish requirements for transparent parts
7. Material Selection
- Choose material for mechanical, thermal and chemical needs
- Consider shrinkage and how it affects tolerances
- Confirm regulatory or flame-retardant requirements
Get a Free DFM Review
D-top Mould provides a free DFM review with every quotation. Send your 2D or 3D drawings and our engineering team will review the design and respond with manufacturability feedback and a quotation within 12 hours.
