The process of photocuring rapid prototyping is an advanced and efficient technique used to create three-dimensional prototypes layer by layer. This method relies on liquid photosensitive resin, which is solidified using ultraviolet (UV) light emitted by lasers, such as helium-cadmium (He-Cd) lasers or argon ion lasers. The process follows a highly controlled sequence, ensuring precision and accuracy for complex prototypes.

The Photocuring Process

The photocuring rapid prototyping process begins with a tank filled with liquid photosensitive resin. The UV laser beams, controlled by a system, scan the resin’s surface point by point according to the part’s cross-sectional data. Each laser exposure causes a photopolymerization reaction that solidifies the resin into a thin layer, which forms one part of the prototype. After one layer is cured, the worktable lowers by the thickness of a single layer, allowing a fresh layer of liquid resin to be added on top of the previous layer. A scraper is then used to level the resin surface, ensuring an even coating. This process repeats with each new layer bonding securely to the one beneath it, creating a solid, fully formed three-dimensional model.

Post-Processing and Final Curing

After the prototype is completed, it is removed from the resin tank, and any excess resin is drained. The support structures, which are necessary for the build process, are then removed, and the model is thoroughly cleaned. The final step involves curing the prototype under UV light to fully solidify the material, ensuring that the part maintains its strength and durability.

Challenges and Solutions in Photocuring Prototyping

One of the main challenges in the photocuring rapid prototyping process is the high viscosity of the resin, which makes it difficult for the liquid surface to level quickly after each layer is cured. This issue can affect the accuracy of the final product. To overcome this challenge, a scraper is used to evenly distribute the resin onto the previous layer. By carefully controlling the amount of resin applied and its distribution, the precision of the final model is greatly improved. The scraper not only helps with leveling the resin but also ensures that the surface is smooth, reducing imperfections.

An additional challenge is the residual volume of resin left on the surface, which can cause inaccuracies. To address this, newer photocuring systems have incorporated an adsorption-type coating mechanism. In this structure, when the scraper is stationary, surface tension causes the liquid resin to fill the adsorption tank. During the scraping motion, the resin from the adsorption tank is evenly applied to the cured resin surface. This method ensures that the resin is spread evenly, enhancing both the smoothness and the overall quality of the prototype.

Advancements in Coating Technology

Another significant improvement in modern systems is the use of front and rear blades within the coating mechanism. These blades help eliminate bubbles that may form due to the movement of the worktable during the build process, ensuring a smoother, more accurate surface on the resin. This feature further enhances the quality of the final prototype, especially in applications where high precision is critical, such as in the aerospace, medical, and automotive industries.

Conclusion

Photocuring rapid prototyping is a powerful and precise method for creating highly detailed three-dimensional prototypes. By utilizing liquid photosensitive resins and advanced laser technology, this process allows for the creation of complex parts with smooth surfaces and high dimensional accuracy. Recent advancements in scraper and coating technologies have improved the precision and surface finish of the prototypes, making this process even more valuable for industries that demand high-quality, fast-turnaround prototypes.