3D printing post-processing process —— Smooth Surface

All 3D printed parts are produced layer by layer, which causes the surface texture of the notches to be more pronounced at lower print resolutions, through smoothing post-processing, a smoother surface, improved mechanical properties, enhanced Beauty etc.

● Grinding & Polishing

Grinding and polishing techniques both remove surface layers by rubbing with abrasive materials. Sanding requires coarser sandpaper and sanding tools, while polishing can use finer sandpaper, steel wool, polishing paste, or a cloth.

Sanding removes larger imperfections, such as support residue or print irregularities, and reduces the visibility of the printed layer. The sanding process leaves grit, although the surface texture is more even, and very rough sandpaper can leave surface scratches.

Polishing the part after grinding produces a smoother surface.

Simplicity and affordability make grinding and polishing the most common post-processing methods, but both are time-intensive and labor-intensive for larger parts and batches. These methods may not be suitable for parts with hard-to-reach cavities.

● Grit blasting

Grit blasting is a subtractive post-processing method in which abrasives are blasted onto 3D printed parts under high pressure. For large parts, this can be done in an open environment, but smaller parts are usually processed in a closed chamber where the abrasive is collected and reused. As with other grit-based subtractive methods, there is a range of grits available, and the grit must be chosen based on part geometry and desired finish. Sand is a common abrasive material, but other small rough objects, such as plastic beads, can also be used for different effects.

Since the abrasive is smaller than the tumbled material, sandblasting is less effective on very rough parts or tall heights. This method only deals with surfaces that are accessible to the stream of blasting material, so complex geometries and cavities may not be feasible. Also, blasting tools can only process a limited area at a given time, so this method can be slower and difficult to process multiple parts at the same time.

● Chemical impregnation

Chemical impregnation, also known as assisted impregnation, is the process of immersing a part in a chemical bath that corrodes the surface. The process involves corrosive materials, such as lye, sodium hydroxide, or methylene chloride, and should only be done by experts in facilities with the necessary safety features. Proper chemical selection depends entirely on the material being 3D printed, as the chemical must be abrasive to the printed material.

It takes some expertise to determine how long the part should be submerged in water: too short and the part will not be smooth enough, too long and it may be completely damaged. Care should be taken to avoid air bubbles becoming trapped inside the 3D print as they will prevent chemical treatment of the surface. Typically, the submerged part is moved gently to agitate the chemical bath and release any air bubbles.

The process is ideal for complex geometries because the chemical bath treats all surfaces of the submerged part simultaneously. However, the size of the chemical dipping vessel dictates a limited part size that can handle prints.

● Grinding & Polishing

If you want to obtain the surface smoothness and glossy appearance of the parts printed by SLS, in addition to the way we usually use manual grinding and dyeing, there is also chemical vapor polishing technology.

The chemical vapor polishing technology uses a special chemical solvent to fumigate the parts in the cabin after vaporization, and the surface of the parts will dissolve. Due to the microscopic inconsistency of the surface, the microscopic convex parts on the surface will dissolve preferentially, and the dissolution rate is faster than that of the concave parts. The lower part; the surface of the dissolved liquid is affected by the tension and tends to shrink as much as possible. The convex part will flow to the concave part. After solidification, a uniform and smooth surface will be produced. Finally, the solution on the surface of the part will be evaporated again. Recycling, there is no residue on the surface of the part, only the original material is left, and then the entire fumigation and polishing process is completed. This way we get fully polished parts.