Surface finishing of additively manufactured stainless steel surgical instruments

Abstract

Purpose Additive manufacturing (AM) has the potential to revolutionise the fabrication of complex surgical instruments. However, AM parts typically have a higher surface roughness compared to machined or fine cast parts. High surface roughness has important implications for surgical instruments, particularly in terms of cleanliness and aesthetic considerations. In this study, bulk surface finishing methods are described to produce end-use selective laser melting parts. Design/methodology/approach The aim was to achieve a surface finish as close as possible to machined parts (Ra = 0.9 µm, Wa = 0.2 µm, Pv = 7.3 µm). A sample coupon was designed to systematically evaluate different finishing techniques. Processes included bulk finishing, blasting and centrifugal finishing methods on individual parts, as well as heat treatment before and after surface finishing. Findings Abrasive blasting or centrifugal finishing alone was not adequate to achieve an end-use surface finish. White oxide vapour blasting at high water pressure was the most effective of the abrasive blasting processes. For centrifugal finishing, a 4 h runtime resulted in an acceptable reduction in surface roughness (Ra = 2.9 µm, Wa = 2.0 µm, Pv = 34.6 µm: inclined surface [30°]) while not significantly increasing part radii. The combination of finishing methods resulting in the smoothest surfaces was white oxide blasting followed by 4 h of centrifugal finishing and a final glass bead blast (Ra = 0.6 µm, Wa = 0.9 µm, Pv = 6.9 µm: inclined surface [30°]). The order of these methods was important because white oxide blasting was significantly less effective when applied after the centrifugal finishing. Originality/value Collectively, these results describe the development of a practical bulk finishing method for stainless steel surgical instruments produced by AM.

Polishing of metal 3D printed parts with complex geometry: Visualizing the influence on geometrical features using centrifugal disk finishing

“…The initial surface roughness on the side of the test part was Ra = 9.49 µm before polishing, which is in line with reported roughness values between 2 and 15 µm Ra for SLM parts [ 14 , 29 , 30 ]. Fig 3A shows the normalized measurements of the width of the test parts before and after polishing, compared with the as-drawn width of the test part (horizontal axis).…”

Technical cleanliness of additively manufactured Inconel 718: a comparative study of surface treatment methods

“…, 2008; Wong, 2009). Soja et al. (2021) stated the potentials of AM for complex surgical instruments and relates surface roughness to cleanliness and aesthetics.…”

Efficient Finishing of Laser Beam Melting Additive Manufactured Parts

“…First of all, additively manufactured parts are usually blasted with particles of hard materials in order to clean the surfaces of the material residue on the one hand and to smooth the peaks of roughness on the other [18,19]. Since this process is not very controlled, the final quality of the component requires further finishing steps [20,21].…”