Whitepaper · HP High Reusability PA12

Automated surface finishing for HP High Reusability PA12

AMT’s patented PostPro3D technology automates the smoothing of thermoplastic 3D-printed parts. This whitepaper tests it on HP Nylon 12 printed on an HP MJF 4200 and reports surface roughness, mechanical properties, dimensions, color, water absorption and cytotoxicity.

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Cover of the whitepaper “Automated surface finishing for HP High Reusability PA12”
With
HP
Material
HP High Reusability PA12
Printing
HP Multi Jet Fusion 4200
Tested on
PostPro3D
Published
  • 0.4%maximum dimensional change
  • 0.3 mmbores smoothed, at the smallest

Source:HP whitepaper, amtechnologies.comPDF (opens in a new tab) published

2022 Published Nov 2022. These tests ran on PostPro3D, the earlier generation of AMT’s automated vapor smoothing systems; today’s systems are the PostPro SF range.

The technology

PostPro3D automates post-processing and integrates into digital manufacturing workflows. Its process, Boundary Layer Automated Smoothing Technology, is a physico-chemical method that smooths complex internal cavities and surfaces with reproducible results and keeps mechanical properties intact. It handles polyamide (nylon) variants, flame-retardant and carbon- or glass-filled nylons, TPU and TPE.PDF

Test method

Calibration pieces and ASTM D638 Type I tensile samples were printed on an HP MJF 4200 and cleaned of loose powder before processing. Surfaces were evaluated as printed, after cleaning and after post-processing.

Design considerations

The process is non-abrasive: it redistributes surface material, so delicate structures survive and bores as small as 0.3 mm are smoothed. Uniform results depend on consistent wall thickness, with 1 mm recommended as a minimum.PDF

Results

  • Surface roughness, measured with a Mitutoyo Surftest SJ-210, improved across three standard finishes, with smaller standard deviations
  • No loss in ultimate tensile strength; elongation at break increased while Young’s modulus decreased
  • Maximum dimensional variation of 0.4%, so tolerances and fine features are kept
  • Color and gloss from gray to piano black in one step, and lower water absorption in immersion tests
  • No cytotoxic effects from extracts of processed samplesPDF

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We vapor smooth your own parts and send them back with the results. No cost to evaluate · Parts returned · Typical turnaround 2–3 weeks1

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