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General Information

Model ID

3DPX-009148

Category

Labware & Devices

Device Use

PBF Post-processing assessments

Keyword(s)

CRRA, FDA, challenge, residue, porous, lattice, PBF, powder

The Challenge Residue Removal Assembly (CRRA) is a research tool designed by OSEL FDA researchers to mimic medical devices, namely orthopaedic, to evaluate challenges in removing additive manufacturing residual materials from porous geometries. The CRRA is a disc assembly composed of a circular base and wedges that slide onto it. The alternating openings on the base create variations in porosity coverage (blind and through porosity) on individual wedges.

A fifteen-millimeter tall blank version of the CRRA is provided. The volumes of the wedges are provided as solid blanks, so that users can modify them with their own porous structures. Two use scenarios have been identified, although the flexibility of the CRRA and further use may help identify more:

CRRA with six (6) identical wedges: n=3 samples of identical porosity with blind or through samples in a single disc
CRRA with three different pairs of wedges: n=1 per combination of porosity/coverage (3 porosity designs)

The CRRA was designed for production with a specific polymer powder bed fusion system (PBF). Changes to clearances between wedges, and at the locking/sliding mechanism may be necessary for ease of production and assembly with other PBF systems, or other additive manufacturing processes.

This challenge assembly, its components, and framework are for illustration purposes only, the end user should adapt them to fit their needs. They do not represent a definitive challenge or test for any specific medical device.

Model Origin

Custom illustration/CAD

How to Make

Print Units

millimeters

Scale At Given Print Units

1:1

Pre- and Postprocessing Instructions

The CRRA is provided as a set of four Stereolithography (STL) files: 1) base, 2) porous volumes, 3) solid shells and 4) wedge trimmers. Files 2-4 contain multiple shells, to maintain alignment of individual porous volumes, solid shells, and wedge trimmers. These should be separated for manipulation.

The porous volume blank file is intended to be edited by the user to create a porous volume. Through Boolean operations, porous volume and solid shell STL files can be joined to form a wedge and subsequently trimmed, if needed, by the wedge trimmer.

Ideally, the wedges will be built assembled onto the base to closely mimic the residual material burden present on printed complex components. If that is not possible, wedges can be built separately and assembled immediately after printing with minimal post-processing and handling.

The groove on the outside of the CRRA was designed to fit a zip tie to hold the assembly tightly together through post-processing and residue cleaning steps. Upon completion of all cleaning steps, the assembly can be taken apart and individual wedges can be assessed for remaining residual material. CRRA wedges can be treated by cleaning processes while disassembled for comparison with assembly-treated wedges.

Attribution

Attribution Instructions

When using this challenge assembly or a modification of it, please acknowledge the FDA Additive Manufacturing of Medical Products (AMMP) Research Facility in Silver Spring, MD.