More from the FDA on Material Characterization for Additive Manufacturing (ODTMag)
In March, I addressed here recent actions by the FDA to increase the specificity of material characterizations. That article focused on a February FDA Draft Guidance on UHMWPE used in orthopedic devices, and also mentioned a Guidance on blood access devices. Now, the FDA has again weighed in on material characterization, this time in the context of a Draft Guidance Document (DGD) on “Technical Considerations for Additive Manufactured Devices,” which includes 3D printing. The general issue of material characterization is how much needs to be specified to know exactly what material is being used in a medical device, and to address whether one material is identical or similar to another material. If similar rather than identical, how similar is it? Is that degree of similarity sufficient to apply experience with one material to expected performance of the other? These issues apply to both the raw materials and those materials as manufactured into a device.
In the DGD, the FDA “recommends,” or is thinking about recommending (since this is a draft) that material specifications begin with the identity of the starting material used in terms of its common name, chemical name, trade name, CAS number, and material supplier. Note that this goes well beyond merely giving a generic polymer name, and reflects that knowing only the chemical name is not knowing very much. In addition, the DGD asks for the identification of processing aids, additives, and cross-linkers used, also by material or chemical name and incoming specifications, certificates of analysis, and test methods. Specifications may include particle size and distribution for powder; filament diameter and diametric tolerances for filaments; viscosity or viscoelasticity, pH, ionic strength, and pot life for fluids; composition, purity, water content, molecular formula, chemical structure, molecular weight, molecular weight distribution, glass transition temperatures, and melting and crystallization point temperatures for polymers or polymer mixtures; and chemical composition and purity for metals. If any material is recycled from manufacturing back into the starting process, this must also be addressed with respect to potential changes in properties and content.
To read the full feature, see it at ODTmag – More from the FDA on Material Characterization for Additive Manufacturing
