What is Post-processing in Rapid Prototyping?

The post-processing of prototyping refers to a series of processes carried out after the completion of machining to improve the surface quality and appearance of the components. Various post-processing techniques have specific roles for different materials and products.

This process includes various techniques such as cleaning, sandblasting, oxidation, silk screen printing, and even laser etching.  Postprocessing not only enhances the aesthetics but also improves the overall quality and accuracy of the prototype. Each post-processing step has its specific function and purpose in improving the surface quality and appearance of the parts. Let’s dive right in.

Types of Post-processing

1. Cleaning: Cleaning is the initial phase of post-processing. When the prototype emerges from the CNC machine, it often leaves chips, rough edges, and metal parts with grease additionally; while processed by 3D printing, the surface is rough, plus with upholder marks and grease. The primary aim of this process is to eliminate chips, grease, and other impurities from the part’s surface, ensuring overall cleanliness.

2. Deburring: It aims to remove any imperfections or irregularities from the part’s surface, guaranteeing a smooth and polished finish. Additionally, certain components feature multiple right-angle characteristics, the CNC machine, due to its round milling cutter, cannot produce, so needs manual deburring of these right angles.

3. Grinding: it is a common surface treatment process that involves using sandpaper to smooth out any tool marks or burrs on the surface of the parts, improving the gloss and flatness of the products.

4. Sandblasting: It can effectively remove impurities, rust, and oxide scale on the surface of the workpiece to ensure surface cleanliness. Sandblasting can increase surface roughness, thereby enhancing the bonding force between the coating and the material. It also can increase the roughness of the surface, making subsequent processes such as painting, spraying, and electroplating more effective.

5. Vapor Smoothing: After sanding and polishing, PC samples still cannot be as transparent as PMMA, so a chemical material is used to fume the PC sample, making it as transparent as possible.

6. UV Varnishing: A layer of transparent oil is sprayed on the surface of the product, which is then dried with ultraviolet light to make the product quality brighter, it results in a scratch-resistant surface and ensures that the color is less prone to fading over time.

7. Spray painting: it is applied according to the client’s color specifications, spraying a layer of paint on the surface of the part to enhance the appearance and protect the surface.

8. Oxidation: it is specifically for aluminum alloy and stainless steel parts, inducing an oxidation reaction on the surface to form a film, enhancing scratch resistance and durability.

9. Silk screen printing: a common printing process used to add specific text or patterns to the surface of metal parts, enhancing the appearance of the products. 

10. Laser Etching: it involves using laser technology to remove paint from the surface of the part, creating various texts, symbols, and patterns to enhance the surface aesthetics.

11. Wire drawing: creates fine textures on the surface of metal parts, improving the product’s texture and meeting specific requirements.

12. Electroplating: it’s a surface treatment that coats specific details of the product with a layer of metallic color, enhancing the appearance and adding value to the product.

13. Polishing: involves using flexible polishing tools, abrasive particles, or other polishing media to modify and improve the surface smoothness and glossiness of the components.

14. Passivation:  it helps stabilize the metal and improve its corrosion resistance by forming an oxide film on the surface.

15. EDM: Electric discharge machining (EDM) utilizes the sparks generated between an electrode and a workpiece when electrified to erode the surfaces layer by layer, enabling the fabrication of complex components such as molds, gears, and turbine blades. It is not limited by workpiece hardness or shape and can handle high-hardness metals and intricate features that are challenging for conventional machining methods to achieve.

In general, the above post-processing steps also expand the application and development potential of CNC machining prototypes. Additionally, it’s important to own skilled masters with extensive experience in various post-processing techniques, so that each process is handled with expertise to meet diverse customer requirements, ensuring the creation of satisfactory products.