Design for manufacturability (DFM), also called design for manufacturing, is an engineering practice in which a product is designed so that it can be made reliably and at reasonable cost. In the formulation of Dewhurst and Boothroyd, a DFM analysis has two steps: choosing the materials and manufacturing processes for each component, then detailing each component to suit that combination. Making these choices well requires cost information at the concept stage, before the parts are fully designed.[1]
In injection moulding
In injection moulding, a DFM review examines a part design, usually as a CAD model, for features that can cause defects or make the mould more complex or costly to build. Features commonly examined include:
- Wall thickness. Thick sections cool more slowly than thin ones, so uneven walls can cause sink marks, warpage and cracking at transitions. The thickest section also tends to set the cycle time.[2][3]
- Draft angles. Side walls, including ribs and bosses, need a slight taper so that the part releases from the mould without sticking. Textured surfaces generally need more draft.[3]
- Ribs and bosses. Ribs are thin supporting walls. Bosses are cylindrical posts, often used for screws. Their thickness relative to the adjoining wall affects the risk of sink marks.[3]
- Undercuts. These are features that prevent the part from being released from the mould directly. Releasing them requires moving mould components, which makes the tooling more complex and more expensive.[3]
- Gate location. The gate is the opening through which molten plastic enters the cavity. Its position influences where weld lines and air traps form, and it can affect residual stress and warpage.[4]
Mould-filling analysis
Mould-filling analysis is a computer simulation of molten plastic flowing into a given mould geometry. When run before the mould is built, it can help predict gate location, fill time, pressure distribution, air entrapment and weld lines. The results depend on the assumed injection conditions and on the experience of the person running the analysis.[5]
References
- ↑ Dewhurst, P.; Boothroyd, G. (1988). "Early cost estimating in product design". Journal of Manufacturing Systems. 7 (3): 183–191. doi:10.1016/0278-6125(88)90003-9.
- ↑ Catoen, Bruce (9 January 2023). "How to Manage Wall Thickness Changes in Your Mold Design". MoldMaking Technology. Gardner Business Media. Retrieved 11 November 2026.
- ↑ 3.0 3.1 3.2 3.3 MLC CAD Systems (17 March 2019). "Top Five Injection Molded Part Design Errors, the Consequences, and How to Avoid Them". Blog SOLIDWORKS. Retrieved 11 November 2026.
- ↑ Florez, Laura (15 August 2025). "Get Gate Placement Right: Tips for Straighter Molded Parts". Plastics Engineering. Society of Plastics Engineers. Retrieved 11 November 2026.
- ↑ Bozzelli, John (27 June 2011). "Mold Filling Simulation: What, When, Why, How". Plastics Technology. Retrieved 11 November 2026.