Calculating the True Per Part Cost for Injection Molding vs 3D Printing
Deciding between 3D printing and injection molding depends on several factors related to production volume, costs, flexibility, and product requirements. Injection molding is ideal for large-scale production where the cost of molds can be amortized across thousands or millions of units, driving down the per-part cost. For instance, a plastic widget might cost only 10 cents per unit when injection molded, compared to 70 cents when 3D printed. However, when you factor in the initial mold cost, shipping, storage, and unsold inventory, injection molding can become more expensive than it appears, especially for smaller production runs.
In contrast, 3D printing offers on-demand manufacturing, eliminating the need for large upfront investments in molds or dealing with excess inventory. This makes it highly flexible, particularly for low-volume production, prototyping, or products with variable designs. For businesses looking to meet niche or fluctuating demands, 3D printing is often the more economical choice, despite the higher unit cost, since it doesn’t require mass production, and print farms can decentralize manufacturing to reduce shipping and storage expenses.
The Tipping Point
Switching to injection molding typically occurs when demand reaches a high enough volume to make the mold investment and inventory costs worthwhile—generally in the range of tens of thousands to millions of units. However, businesses must also consider physical differences between injection-molded and 3D-printed parts, as each method produces distinct mechanical properties, surface finishes, and tolerances.
Ultimately, the decision hinges on specific project needs, desired flexibility, and cost calculations over the production lifecycle. For low to moderate volumes, 3D printing is often the better option, but for long-term, high-volume production, injection molding becomes more cost-effective once the mold and logistical costs are spread out across a large number of units.
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