3D Printing Post-Processing – Surface Finishing

With the constant growth of Additive Manufacturing and ever-expanding fields of application, the demand for 3D printed end-use parts is increasing. Two features of 3D printed parts are; the stair-casing effect due to the layer-by-layer build process and, the smooth sandpaper surface finish.

Surface smoothing and dyeing are often required for end-use polymer parts.

Surface finishing on 3D printed polymer parts

To obtain the required surface finish on polymer 3D printed parts, post-processing operations such as manual sanding, vibrating bowl abrasive machining, ultrasonic abrasion finishing, chemical machining, laser surface finishing, and abrasive flow machining are commonly used.

Surface finishing on 3D printed metal parts

There are several post-processing processes that can be used to achieve the desired surface roughness or finish of Atomic Diffusion Additive Manufacturing (ADAM) Metal 3D Printing and Direct Metal Laser Sintering (DMLS) built parts.

These include abrasive blasting (grit and ceramic), shot peening, polishing, electrochemical polishing, optical Polishing (hand finishing), CNC finishing or machining, abrasive flow machining (extrude honing), polishing, electroplating, micromachining process (MMP).

Automated Surfacing for Powder Bed Fusion Polymer Parts

Market-ready products manufactured, using powder bed fusion technologies such as Selective Laser Sintering (SLS) or Multi Jet Fusion (MJF) must meet aesthetic and functional requirements.

These requirements vary depending on the product, industry, and application.

In many applications, powder bed fusion produces rough surfaces compared to conventional manufacturing methods. Untreated, the rougher surface is predisposed to collecting dirt, reducing the suitability for end-use, market-ready parts.

Choosing the post-processing surfacing process, best suited to the end result, will determine further processing feasibility, cost efficiencies, and desired final finish. Consistent surface homogenization is also critical if the 3D printed parts are being dyed, requiring consistent results.

Changing the surface smoothness using post-processing can produce unintended results. For example, abrasive tumbling of 3D printed polymer parts removes material to achieve smoothness. This can cause damage and affect part fit and function.

Rapid 3D, a leading supplier of industrial 3D printing-related post-processing systems, and the South African DyeMansion authorised partner, offers two proprietary polymer surface finishing solutions, purpose-designed for surfacing 3D printed polymer parts.

PolyShot Surfacing (mechanical)

The most efficient mechanical technology to achieve an end-use part finish.

During the PolyShot Surfacing (PSS) process, beads are shot at the surface of the parts. This process aligns the peaks and troughs on the part surface, reducing the roughness and homogenising the surface.

Contrasted to tumbling, where the material is removed, PolyShot surfacing deforms the plastic surface in the microscopic range. In this process, no material is removed and the original geometry of the part is retained.

PolyShot Surfacing Properties

PolyShot Surfacing Limitations

With thin tubes or labyrinth structures, the degree of homogenization achieved by PSS can vary. The reason is that the energy applied to internal geometries, outside of the line of sight, is lower after the deflection of the beads. Longer process durations can mitigate this to some dege.

Heavy parts, with fragile geometries such as antennas or pins, can be damaged during processing. While PSS is perfectly designed for processing hard polymers such as PA11 or PA12, it is not suitable for flexible materials such as TPU, as the elasticity of the material absorbs the energy.

PolyShot Fields of Applicability

PolyShot Surfacing is well established in the 3D printing market due to the surface quality standard. In particular, the processing of parts produced with Powder Bed Fusion technologies is more efficient and simpler than others.

The process is suitable for all applications that require a scratch-resistant, matt-glossy, and above all coloured surfaces. These include orthotics like prostheses and orthoses. Eyewear in the lifestyle sector and automotive interior parts are other proven applications. the process is already being used in a wide range of industries.

VaporFuse Surfacing (chemical)

The clean vapour surfacing technology challenging injection moulded part finishes. Compatible materials: PA, TPU, ULTEM and more.

VaporFuse Surfacing Properties

VaporFuse Surfacing (VFS) delivers sealed and washable parts with injection moulded like surfaces.

This is achieved by flooding the process chamber with vapour, under a vacuum. This ensures reproducible surface processing of complex geometries and internal surfaces. This process ensures a surface roughness that is reduced to a minimum.

VaporFuse Fields of Applicability

VFS works for all common plastics and particularly for flexible polymers such as TPU, for which mechanical techniques are not suited. VaporFuse Surfacing;

• Washable, sealed surfaces
• Solvent approved for food contact
• Suitable for all common hard & flexible plastics

The system offers fully automatic loading, connectivity, and batch tracking features. Validated and specially developed programs for all common materials are available and ready to use. In addition, all process parameters can be adapted individually for other materials. This ensures flexibility and seamless integration with existing production processes such as the DyeMansion Print-to-Product workflow.

POWERFUSE S PP

The green vapour polishing solution for highly industrial manufacturing & surface improvements beyond aesthetics. The first ever vapour polishing solution to smooth 3D-printed polypropylene. Compatible materials: PP only.

Download DyeMansion POWERFUSE S PP Datasheet