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The Prototyping Blog

the prototyping blog

3 Types Of Plastic Prototypes: Which One Is Right For You?

Posted by Matt Sweeney on Feb 19, 2015

Trends_PrototypingWith so many advancements in prototyping over the years, engineers, mechanical designers, model makers and tooling professionals are struggling with which prototyping option is best for their plastic parts.

Whether you are working on or tweaking an existing part or beginning a new design from scratch, it is imperative to know the differences between the prototyping options that are available for plastic parts. Let’s consider the pros and cons to each way you can make this process happen.

  1. 3D Printing

3D printing is one of the more recent trends in the plastic prototyping industry. While there is a lot to gain from 3D printing, this technology has limitations as well. By producing low-cost prototypes early in the design process, a number of features such as form, fit and function can be gauged and compared with design iterations without commitment. Additionally 3D printers are affordable, compact units that easily fit into an office environment. 

3D printed parts are not as strong as injection molded parts. With injection molding, you have even strength throughout the part as well as consistent material structure. Additionally, with 3D printed parts, cost is based on material used – so the bigger, the more expensive. Cost, however, does not necessarily pertain to complexity or number of parts.

Pros: 

  • Fast & Portable

Cons: 

  • Part cannot be used in functional testing
  • Part may be weak and brittle
  • Many limitations in regard to types of materials that can be used.
  • Material shrink / contraction will not be determined with 3D printing
  1. Rapid Prototypes

Rapid prototypes are made with aluminum molds for quick turnaround. While aluminum molds can be constructed faster than steel, there are typically limitations in regard to design features, material, and quality. 

Compared to 3D printing, rapid injection molded prototypes are produced with more accuracy and strength. However the design and development of these parts do not always align with what is needed to bring the part through to production. There are constraints on the modifications that can be made to the part. So while you may be saving time and money upfront, the process could end up costing more in the long run. That's why rapid injection molding is good for an early stage prototype but not necessarily for functional parts. Here are the pros and cons of rapid prototyping to consider:

Pros:

  • Fast turnaround 
  • Cheaper tooling investment
  • Functional testing is possible, but limited

Cons:

  • Features may be left out of part due to process limitations
  • Some limitations in regard to types of materials that can be used as well as texture
  • Minimal engineering support
  1. Production Quality Prototypes

Production-quality prototypes are meant to replicate the final production part. They are often used to make sure the parts are completely functional before investing in a production mold. The main difference between a production-quality prototype and a rapid prototype is the quality of the mold. Production-quality prototypes are made using steel molds whereas rapid prototypes use aluminum. The use of steel, as well as the production mold features incorporated in the tooling, gives engineers the opportunity to test-run their final design and material choice prior to mass production. This method reduces the risk of finding a flaw in the design after manufacturing millions of parts. 

Consider these other pros and cons when determining if a production-quality prototype is the best fit for you:

Pros:

  • Design recommendations may be made, but customer design specifications are not compromised
  • Customers can use their exact choice of material, including abrasive/filled materials
  • Parts replicate what is needed for real-life testing
  • Parts are made with an ability to add tolerance
  • A production approach is taken throughout the design and development process
  • In-depth ability to learn from the design and part development process
  • Material shrink / contraction can be planned for during design process and inspected during development

Cons:

  • Process may take longer than 3D printing
  • Cost may be greater upfront but equal in the long run when considering the quality, functionality and absence of compromises made throughout the process

At the Engineering Resource Center, production-quality prototypes are our niche. Our production-style prototype tooling allows customers to develop prototypes to their exact design specifications without the expense of an entire steel production mold. It's a win-win if you need a functional plastic prototype and cannot risk the limitations of a rapid prototype. Another bonus? Since a production-quality prototype is identical to the final production part, you can use the same mold to produce over 100,000 production parts if you need small initial quantities.

Few new technologies have impacted product development as much as 3D printing, rapid prototyping, and production-quality prototyping. Globally, organizations continue to discover creative uses for the technologies available to expand product offerings and accelerate time to market. As these technologies continue to develop, plastic prototyping will further expand into industries that may have ignored or resisted in the past. Growth into new markets and industries will redefine the role of plastic prototyping and will redefine the future of product manufacturing.

What other trends are you seeing in the plastic prototyping industry?

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