With the popularization of 3D printing technology, more and more enthusiasts and professionals begin to use 3D printers to make various parts and models. However, because 3D printing is completed by stacking materials layer by layer, the surface of the finished product usually has lamination, burr or other uneven phenomena, which affects the aesthetics and usability. Therefore, it is a crucial step in the post-processing to polish 3D printed parts to make their surfaces smoother.

First, the preparation before polishing

Before you start grinding, you should first understand the type of materials used in the printed parts. Common 3D printing materials include PLA, ABS, PETG, nylon, resin, etc. Different materials have different hardness and polishing characteristics, so it is necessary to choose appropriate polishing tools and methods. In addition, it is necessary to prepare sandpaper (with different particle sizes), grinding tools (such as angle grinder or grinding pen), protective equipment (such as masks, gloves and goggles) and cleaning supplies.

Second, the basic steps of grinding

1. Remove the supporting structure and burr.
First, use scissors or a knife to remove the redundant supporting structure, and gently polish the residual traces with fine sandpaper to avoid scratching other areas of the surface in the subsequent polishing process.

2. Rough grinding
Use coarse sandpaper (such as 120-240 mesh) to remove obvious layering and smooth the surface. Grinding should be carried out in the same direction to avoid irregular scratches caused by rubbing back and forth.

3. Medium grinding
Replace it with sandpaper with higher granularity (such as 400-600 mesh) and continue grinding to further eliminate the traces left by rough grinding and make the surface smooth.

Step 4 fine grinding
Use 800-1200 mesh or even higher grit sandpaper for fine grinding until the surface is smooth without obvious scratches. This step requires patience and careful operation to ensure that everything is polished in place.

5. Polishing (optional)
For the model with higher requirements, polishing tools or polishing paste can be used for final polishing treatment, so that the surface presents luster similar to that of injection molded parts.

Third, the polishing skills of special materials

For resin parts printed by light curing (SLA) printer, because of its delicate surface, we can skip the rough grinding step and start directly from the medium grinding. Nylon parts, on the other hand, should be dried before polishing because of their strong water absorption to prevent sandpaper from blocking.

For ABS materials, acetone steam fumigation can also be used for surface treatment to make the surface melt and smooth, but this method requires high operating environment and safety.

Fourth, matters needing attention

Wear protective equipment during grinding to prevent dust inhalation and skin irritation. At the same time, excessive grinding should be avoided to avoid damaging the model structure or causing local depression. It is suggested to clean the model surface with alcohol or water every time the granularity of sandpaper is changed, so as to observe the polishing effect.

tag

Through scientific and reasonable grinding process and technical means, 3D printed parts can reach the surface quality close to industrial products. Good surface treatment can significantly improve the overall quality of the work, whether it is used for exhibition, functional test or further spraying and coloring. Therefore, mastering polishing skills is not only a practical post-processing skill, but also an important part of improving the level of 3D printing.