Plastic 3D printed components after processing.
After using the technology for just under a year, leading design and model-making bureau Ogle Models and Prototypes has prepared a set of guidelines to assist other companies in using vibratory bowls to finish 3D printed parts.
Earlier this year, the company installed two EVP250 vibratory bowls from PDJ Vibro to automate and speed finishing of plastic components made by selective laser sintering.
Amanda Offen, a member of the firm’s rapid prototyping team suggests some tips, which could reduce preparation time for painting plastic components by one third in comparison to hand finishing.
It is important to fill a bowl with a ceramic abrasive medium of a size and shape that will fall away from the smallest, most confined spaces within 3D printed components, which can contain very complex, awkward areas.
For parts with thin edge detail, this type of finishing is not recommended are the abrasive nature can cause edges to be rounded.
Guidelines for surface features show that those smaller than 1mm cube should not be vibro-finished and around 0.05 mm to 0.10 mm is removed from the surface of components printed from PA2200 polyamide powder and the PA3200GF glass-filled alternative.
Cavities within a 3D printed component can be impossible to remove without destroying the part.
A similar material used by Ogle, called Alumide, is filled with aluminium particles. The detail can be more fragile when laser-sintered, requiring a minimum of 2 mm cube surface detail, 2.5 mm square cross section and 1.5 mm wall thickness.
Ogle is currently investigating the possibility of vibro-finishing flame retardant polyamide.
With all three polyamide materials, flat surfaces and areas of gradual curvature are smoothed well in the PDJ Vibro bowls, creating a satin-like finish which can be enhanced by Ogle’s durable ColourPro dying process.
Parts also become more flexible after vibratory finishing, as the plastic absorbs water from the PDJ Vibro bowl, replacing some of the material’s natural moisture that is lost during laser sintering at 175 to 180°C.
Ogle’s RP director, Steve Willmott, commented, “The PDJ Vibro bowls are the first vibratory finishing machines we have used. We are saving a lot of time when preparing our customers’ components, especially those that have been 3D printed in our SLS equipment.
