3D Printed Polymer Surface Smoothing with UV-Absorbing Colorant
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Solution Overview
Problem
3D printed polymer objects produced by multi-jet fusion (MJF) processes have rough surfaces due to partially fused and adhered powder particles, which degrade optical appearance and require methods to achieve a smooth finish.
Innovation Solution
A post-printing method involving coating the surface with a UV absorbing colorant, followed by UV irradiation to melt and reflow the polymer surface, achieving a smooth finish with a surface roughness of ≤5.0 μm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If 3D printing is used to manufacture polymer objects, then production flexibility and rapid prototyping capability are improved, but surface roughness increases due to partially melted particles
Solution Approach 1:
The patent applies phase transition by melting the rough polymer surface using UV-induced localized heating, causing the partially melted particles to reflow and fuse into a smooth surface. The UV-absorbing colorant converts UV energy to thermal energy, raising the surface temperature above the polymer's melting point temporarily, allowing the material to transition from solid to molten state and then resolidify as a smooth surface.
Solution Approach 2:
The UV-absorbing colorant acts as an intermediary substance applied to the 3D printed object's surface. This colorant absorbs UV radiation and converts it to heat, which then melts the polymer surface. The colorant enables selective heating without directly contacting or mechanically altering the surface, serving as a mediator between the UV energy source and the polymer material.
2Manufacturing precision
If injection molding is used instead of 3D printing, then surface quality is improved, but production flexibility and rapid prototyping capability are reduced
Solution Approach 1:
The patent applies preliminary action by first coating the 3D printed object with a UV-absorbing colorant before performing the surface smoothing operation. This preliminary coating enables the subsequent UV irradiation to effectively melt and smooth the surface, achieving injection-molding-quality surfaces on additively manufactured parts without requiring retooling or redesign.
3Manufacturing precision
If UV irradiation is applied to melt the surface, then surface roughness is reduced, but energy consumption increases
Solution Approach 1:
The patent applies local quality by concentrating UV irradiation energy only on the surface layer of the 3D printed object where smoothing is needed. The UV-absorbing colorant is applied only to the surface, ensuring that energy is absorbed locally at the surface rather than throughout the entire object. This localized energy application minimizes overall energy consumption while achieving the desired surface finish.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method effectively reduces surface roughness to ≤5.0 μm without distorting the object's shape or dimensional profile, improving optical appearance and surface quality.
Implementation Method 1
coating a surface of a 3D printed object with a UV absorbing colorant, irradiating the surface with UV light to form a melted surface
Implementation Method 2
irradiating the surface with UV light to form a melted surface
Data Source
AI summary
A three-dimensional (3D) printed object is described. The 3D printed object comprises a polymer. A surface of the 3D printed object comprises the polymer 5 and a UV absorbing colorant. The surface has a surface area roughness Sa (arithmetical mean height) of ≤5.0 μm. A method for preparing a three dimensional (3D) printed object having a smooth surface is also described.