How to move from 3D printing to injection molding

Additive manufacturing has a firm place in product development, but how and when do you transition from 3D printing to molding?

Jean Thilmany, Proto Labs

Call it 3D printing or call it additive manufacturing, the terms are often used interchangeably now. Whatever the preferred nomenclature, parts made by applying thin sheets or threads of material, layer after layer, play a valuable role in developing a product that has the potential to shift to injection molding.

Printed parts can act as prototypes before final design or be used to assess the initial form, fit, and sometimes functionality of parts within a product. Should the part be needed in greater quantities in the future, a company can then ramp up to injection molding.

Though 3D printing and injection molding share some similarities in plastic and metal materials and the process of designing a 3D CAD model, they differ in some crucial ways. Designers and engineers will need to keep a few things in mind as they move from one to the other.

Additive manufacturing allows for the rapid prototyping and physical testing of a design, so designers can iterate quickly and reduce their products’ time to market. Whether they need a small, thin-walled part, one with complex geometries, or a large, durable prototype or bridge part, they can have a 3D-printed part, or set of parts, made quickly to avoid the initial tooling expense of prototyping a limited amount of injection-molded parts.

Of course, many—if not most—engineering companies don’t have access to the expensive machines needed for 3D printing. That’s not a problem. They can easily turn to an outside supplier.

While additive processes turn out sample parts quickly and at lower cost than some conventional manufacturing methods, there are challenges to using 3D printing for mass production. The costs could exceed that of injection molding if used for anything beyond small runs of no more than a few hundred parts.

Print, machine or mold?