Stratasys Blog

Additive Mfg vs Molding: The Accuracy Hurdle is Fading

Additive manufacturing processes are now used for production applications. Manufacturers are using FDM and competitive processes for:

  • Bridge-to-tooling
  • Custom manufacturing aids
  • Short-run production lots of 100 to 2,000

In these applications, accuracy demands are stringent and often expected to be as good as molded parts. Over the last several years, the FDM process has been gaining acceptance as a proven accurate alternative.

For traditionally molded parts, the tolerance range of a thermoplastic or a thermoset is ±0.008 to ±0.002 inches. Although the FDM process cannot achieve the same smoothness as injection molding, results from a recent study indicate its accuracy is actually within the same range as molded parts. This report shows the FDM 400mc (aka the Fortus 400mc) is a stable platform with repeatable dimensional accuracy in the same range as molded parts.

FDM Technology

Test results from 108 FDM parts.
(Deviation from nominal dimensions from all parts on FDM 400mc machines)

RedEye has around 25 machines based on the 400mc platform, and it has several 900mc machines that can produce parts that hold a tolerance of 0.003 inch. Accuracy and repeatability of parts from machine to machine is critical for large-scale prototype jobs and low-volume production applications, and RedEye runs these types of jobs every day.

Back in 2003, Time Compression Technology published ‘Fused Deposition Modeling a Technology Evaluation‘. This study evaluated the accuracy of FDM parts from three Stratasys FDM machines and compared them against the accuracies of three other popular processes: SLA, SLS, and PolyJet, which were evaluated in a separate, preceding study. The study concluded that “When material properties, accuracy of parts, repeatability from part to part, and part stability over time is absolutely critical, FDM thermoplastics are the ideal choice.”
Get a free sample part from Stratasys and evaluate FDM technology.

Tim Thellin

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