The Finishing of Stereolithography Models Using Resin Based Coatings

The use of StereoLithography (SL) can produce accurate prototype models with complex internal and external features. However, a major problem to commercial use is the poor surface finish caused mainly by 'stair stepping' which is inherent in layer manufacturing. Models are often finished by hand but this is labour intensive, highly selective and causes inaccuracies in the model geometry. A three-year research project has been undertaken to address these issues and to investigate a range of surface coatings and mechanical finishing processes applied to SL models. This paper describes some initial findings using resin coatings applied to both cured and uncured SL parts.Initial findings suggest that excess resin retained after part stripping can result in a lower surface roughness than parts thoroughly cleaned prior to post curing.Through the addition of photocurable and epoxy based resins to parts in both the un-cured, green and cured states, surface roughness has been seen to be reduced by up to 50% on complex parts.