First, the necessity of SLS powder recovery

In the process of SLS printing, only part of the powder is melted by laser to form the final part, and the rest is used as supporting structure or filling material, which usually accounts for more than 50% of the total powder used. If these "waste powders" are directly discarded, it will cause great waste of resources and increase the environmental burden. In addition, powder materials for SLS (such as nylon 12, TPU and other polymer materials) are expensive, and recycling is helpful to significantly reduce production costs.

At the same time, the powder may undergo thermal degradation, oxidation or particle morphology changes after many heating and cooling cycles in high temperature environment, which may affect its printing performance. Therefore, scientific and reasonable recycling mechanism and quality control means are particularly important.

Second, the recovery method of SLS powder
　　The recovery of SLS powder mainly includes the following steps:

1. Collection and screening: After printing, take the unformed powder out of the molding chamber, and remove large-particle impurities and caked powder by screening equipment to ensure its fluidity.

2. Thermal history evaluation: The thermal stability of the powder is evaluated by means of thermogravimetric analysis (TGA) or differential scanning calorimetry (DSC) to determine whether it is suitable for continuous use.

3. Mixing and regeneration: In order to make up for the performance degradation caused by thermal degradation in the recycled powder, the recycled powder is usually mixed with a certain proportion of new powder in proportion (such as 30%~50%) to ensure the printing quality and parts performance.

4. Storage and management: reasonably controlling the storage environment (such as temperature, humidity, etc.) of powder, and establishing a powder use file to record its use times and thermal history will help to prolong the service life of powder.

Iii. Environmental Protection and Economic Benefits

By recycling SLS powder, enterprises not only reduce the cost of purchasing raw materials, but also reduce the cost of waste treatment and improve the efficiency of resource utilization. In addition, this process is also in line with the global concept of green manufacturing and circular economy. For example, some leading 3D printing enterprises have begun to adopt closed-loop powder management system to realize efficient recycling of powder and reduce carbon footprint.

Fourth, the future outlook

With the progress of science and technology, more advanced powder regeneration technologies may appear in the future, such as chemical regeneration, nano-coating repair and other methods, to further improve the performance of recycled powder and make it close to or even reach the level of new powder. At the same time, the development of intelligent powder management system and AI-aided evaluation technology will also provide strong support for the sustainable utilization of SLS powder.

In a word, the recovery and reuse of SLS powder is not only an effective way to reduce the manufacturing cost, but also an important measure to realize green manufacturing. While promoting the popularization of 3D printing technology, we must attach importance to the recycling of resources and contribute to the construction of a sustainable manufacturing system.