While injection molding may seem costly compared to processes like CNC machining and 3D printing, the ability to scale and manufacture thousands of parts makes it a cost-effective solution for mass production. Determining the cost of injection molding is a combination of several factors. The main determinant of molding cost is the amount of time it takes to produce the tooling. This means, the more complex the part’s geometry, the higher your manufacturing costs will be. Simple parts, without undercuts or more advanced surface finishes, will be the most affordable.

Undercut illustration
Undercuts, such as those shown, can complicate and, in some cases, prevent part ejection, so eliminate them if possible.
In addition to per-unit costs, consider the material. Many plastics overlap in strength and functionality, but some are inherently easier to mold, driving down part costs. You can experiment with different materials in the interactive quote you receive when you upload your design to Protolabs.

Here are 11 injection molding design considerations to stretch your manufacturing dollar:

1. Eliminate undercuts
2. Get rid of unnecessary features
3. Use a core cavity approach
4. Reduce cosmetic finishes and appearances
5. Design self-mating parts
6. Modify and reuse molds
7. Pay attention to DFM analysis
8. Use a multi-cavity or family mold
9. Choose on-demand production option
10. Consider part size
11. Use overmolding