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When it comes to producing plastic parts in prototyping and low-volume applications, there are three main options: 3D Printing, Urethane Casting, and Low-Volume Injection Molding. Which is best for your needs?

First, let’s quickly define each of the techniques:

  • 3D Printing is an additive process of creating a plastic or metal object from a 3D model, using a machine that either lays down thin layers of material in succession, or focuses a laser on powder or liquid to melt/harden the layers.
  • Urethane Casting is the process of first creating a mold (either 3D printed or milled aluminum), then using that mold to make multiple castings of a product out of certain types of rubber or plastic that cure at room temperature.
  • Low-Volume Injection Molding involves using a metal mold (either aluminum for low volume or steel at higher volume) to make castings of a product out of melted plastic or metal.

There are differences in the capabilities and costs associated with each, and each has advantages for specific applications. Which one is better for you depends on the requirements of your particular project.

Some projects might be best suited to one over the others, while other projects might necessitate using more than one of the techniques.

To help you compare the techniques methods and determine which one (or more) best for any particular project, we developed this table:

Variable 3D Printing Urethane Casting Low-Volume Injection Molding
Ideal Quantities 1-50 units 5-250 units 250+ units
Surface/Part Detail Not as good for highly intricate surfaces Picks up subtle surface details Creates parts with high levels of detail
Materials Limited range of plastic at the low end, though high-end 3D printing supports a broader plastic and metal materials Limited range of materials, typically rubber or plastic that cure at room temperature Broad range of materials, both plastic and metal in melted form (starting with beads or powder)
Fixed Costs –

Equipment & Mold

3D printers range from $500 to $500,000 or more

No mold needed.

Very little required equipment

Low mold cost. 3D printed plastic for prototypes, Aluminum for low-volume, harder materials.

Equipment $10-20k on low end

Medium to high mold cost. Aluminum for low volume (1-10,000), steel for higher volume (10,000+)

Per-Unit Cost High per-unit cost Moderate to low per-unit cost Very low per-unit cost especially at high volume
Domestic vs. Off-shore production Ideal for US-based production Ideal for US-based production US-based production only for short lead-times, high budget, lower volume
Ideal Application Prototyping & iterative design Creating replicas High-volume production

In the coming weeks, we’ll share blog posts that explore the different variables in greater detail. If you have any questions about any of the methods, contact us. We’ll be happy to discuss your project and answer your questions.



PartWorks, LLC
6100 Emmanuel Dr., SW
Atlanta, GA 30336.
(470) 231-PART (7278)