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How To Make Prototypes That Are Just Your Type!

June 30, 2015

Even if 3D printing eventually usurps plastic injection molding — and that’s a BIG if — prototypes will continue to play an indispensable role in the production of plastic parts.

Why?  Simply put, prototypes are crucial to several steps which precede the actual production of parts. These include communications, engineering studies, market studies (to evaluate product marketability and assembly characteristics) and to verify CAD model or print accuracy.  Regardless of the material from which they are made (and, increasingly, they are made from plastic), prototypes generate physical models that act as a common “language”  between internal teams such as marketing, engineering, tooling and product manufacturing.  Nothing but a prototype can communicate the function, size, shape, feel and look of a part instantly.  This inevitably leads to a more collaborative environment and more efficient interaction between the various teams.

Prototype parts are categorized as being either  1.) facsimile prototypes, which can serve both marketing and perhaps limited engineering functions, or 2.) processing prototypes, (i. e., those produced using prototype injection molds or tools), which are used to evaluate both the molding process and the molded part properties, before production tooling is fully committed.  It is likely that at least one, or perhaps a series of facsimile prototypes  would have been made before a company commits to the cost of actual pre-production or prototype tooling. This latter step can add significant time and initial cost to the process of product development. However, this step is vital when working with new and unfamiliar materials, complex product geometries, structural parts, or tighter tolerance applications.  After all, the function and fit of a molded plastic product are strongly influenced by the tool design and the manufacturing and injection molding conditions.

Pre-production tool trial results allow the mold designer to fine tune the production mold design, and provide the design team with a potentially large number of nearly “real life” parts, which may be required for advanced marketing or engineering studies.  Of course, computer-aided design simulation software for injection molding has reduced the need for prototype tooling considerably.  Filling, cooling, shrinkage and warpage analysis packages are providing answers that were previously available only through actual molding trials. A well designed simulation study will provide information on weld line locations and potential part weaknesses, possible gas traps, part warpage or internal (molding) and stress levels.

In short,  prototyping and prototypes will be with those of us who work in plastic injection molding for years, if not decades, to come.


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