3D Metal Printing Using Laser Powder Bed Processes in the Food : Industry Impact of Post-Processing Methods on Surface Quality and Removal of Specifically Introduced Microbiological Contaminants

Additive manufacturing using laser powder bed fusion offers the food industry significant advantages, including optimisation of design and space utilisation, weight reduction, minimisation of warehousing and a reduction in individual components and weld seams.However, current post-print surfaces do not meet the industry's stringent hygiene requirements, necessitating the use of post-processing techniques.In this study, microbial investigations were carried out following the EHEDG Doc. 2 procedure using a model contamination and the test organism Geobacillus stearothermophilus to compare different post-processing methods.The results show that the roughness of components produced by Laser Powder Bed Fusion (LPBF) can be reduced from Ra = 4.3 m to as low as Ra = 0.7 m by the post-processing method of abrasive flow machining (AFM).A direct correlation was found between surface roughness and microbial contamination, with lower Ra values correlating with lower microbial presence.Although the hygienic requirements were met, the AFM finished components could not be completely cleaned due to grinding marks.