3D printed vs injection molded plastic parts – What’s the difference?

UL’s independent research study on the safety and performance variability for 3D printed plastic parts provides the proof.

3D printing – or additive manufacturing (AM) – offers unprecedented versatility to manufacture complex parts and products directly from digital files. Printing parameters can be changed during the process, tailoring material properties to perfectly fit any given portion of a printed product. This incredible versatility, however, introduces a new level of complexity not seen in conventional manufacturing.

In the AM industry, the mechanical properties of a material, such as tensile and impact strength, will vary considerably more when 3D printed than molded by conventional methods, such as injection molding. Less commonly understood, however, is that 3D printing may influence a material’s safety-critical performance properties, such as ignition, flammability and dielectric strength.

Our plastics experts conducted a systematic research study to fill in this knowledge gap.  UL investigated the flammability, ignition and electrical properties of samples that were 3D printed against samples manufactured using conventional, injection-molded methods. Researchers identified significant safety and performance variations and concluded that performance ratings from traditional manufacturing techniques cannot be applied when the same material is used in a 3D printing process to print a 3D part.

UL’s white paper ‘Certifying plastics for additive manufacturing’ provides a summary of the research findings:

• Get an overview of our research study investigating the effects of 3D printing versus material extrusion on safety critical performance properties
• Understand why performance ratings from traditional manufacturing techniques cannot be applied when that same material is used in a 3D printing process to print a 3D part
• Find out how our research findings were used to establish our certification program for Plastics for Additive Manufacturing (Blue Card)
• Learn how the UL Blue Card program can accelerate the adoption of 3D printing into serial production

A copy of the detailed research study is also available for download.

Still unsure which trusted UL Plastics Certification Program you should be using?

Plastics materials need to meet rigorous safety standards.  UL’s various plastics recognition programs offer globally recognized safety, performance and quality verification – but which one do you need? This handy infographic can help guide you through the choices.

For more information on UL's services for Additive Manufacturing (AM) and AM materials certification programs, visit:
www.ul.com/AM
www.ul.com/BlueCard