SLS 3D Printing
Fused Deposition Modelling
Selective Laser Sintering currently supports a limited range of materials for printing. Thermoplastics such as polyamide (Nylon), commonly in the form of PA11 and PA12, and TPUs are commonly used in SLS due to their mechanical properties and durability. Nylon materials offer good strength-to-weight ratios and are suitable for functional parts and prototypes. Additionally, SLS can work with various composite materials, including glass-filled, carbon-filled, or metal-filled powders. These composites provide enhanced strength, rigidity, or thermal conductivity for specific applications. Material selection depends on the desired properties of the printed object, including strength, flexibility, thermal resistance, and chemical compatibility.
Materials
In FDM printing, a wide range of thermoplastic materials can be utilized, offering versatility for different applications. Common thermoplastics suitable for hobbyist use and ease of printing include Acrylonitrile Butadiene Styrene (ABS), known for its durability and impact resistance, making it suitable for functional prototypes and end-use parts. Polylactic Acid (PLA), a biodegradable material derived from renewable resources, offers an environmentally friendly option. PLA has a low melting temperature, making it easy to extrude and reducing energy requirements. It exhibits good dimensional stability, low warping tendencies, and offers good layer adhesion, contributing to the strength of printed objects. Polyethylene Terephthalate Glycol (PETG) provides improved strength and chemical resistance, making it suitable for engineering applications. Additionally, FDM printing incorporates the use of advanced materials such as Polyether Ether Ketone (PEEK), Polyetherketoneketone (PEKK), Polyetherimide (Ultem) and carbon fiber- or metal-reinforced materials. These high-performance materials offer exceptional thermal resistance, chemical inertness, and mechanical properties, making them ideal for demanding applications in industries like aerospace and medical fields. Nylon with Glass Fiber (PA-GF) combines the strength of nylon with added rigidity and toughness due to the glass fiber reinforcement, making it suitable for structural components. The material choice depends on the desired characteristics of the printed object, such as strength, flexibility, heat resistance, chemical resistance, and specialized applications, allowing FDM to address a wide range of manufacturing needs.
Machines
SLS 3D printers are available in different categories to meet various manufacturing needs. Desktop or benchtop SLS printers are suitable for smaller-scale applications and are often used in research laboratories or educational settings. These machines offer lower costs and smaller build volumes compared to industrial-grade SLS printers. Industrial-grade SLS printers are designed for large-scale production and can accommodate larger build volumes. They typically offer faster print speeds, higher precision, and advanced features for improved process control and part quality. SLS machines may also vary in terms of laser power, scanning speed, and powder handling systems, depending on the specific manufacturer and model.
Post-Processing
After the SLS printing process, post-processing steps are often required to achieve the desired final product. One of the advantages of SLS is that the printed objects do not typically require extensive support structures, as the surrounding powder acts as temporary support during the printing process. Once printing is complete, the objects are removed from the powder bed and undergo post-processing treatments. These treatments may include removing excess powder, cleaning, and surface finishing. Depending on the complexity of the geometry, support structures may be cumbersome to remove in post-processing. Surface finishing techniques such as sanding, polishing, or chemical treatments can be applied to enhance the appearance and smoothness of the printed objects.
Pros and Cons
Selective Laser Sintering offers several advantages that make it a preferred choice for certain applications. SLS enables the production of complex geometries and intricate designs that are difficult or impossible to achieve with traditional manufacturing methods. However, SLS is known to be vulnerable to shrinkage and warping resulting from the laser fusing the powdered material. Adequate design considerations and optimization techniques are necessary to minimize these effects. Furthermore, SLS printing requires a controlled environment to ensure consistent powder quality and laser performance. Factors such as temperature and humidity can influence the outcome of the printing process, making environmental control a critical aspect of successful SLS printing. Nevertheless, SLS enables the creation of functional prototypes, end-use parts, and customized components with excellent accuracy and detail. SLS is a cost-effective option for low- to medium-volume production, as it eliminates the need for expensive molds or tooling. The ability to print with a wide range of materials, including composites, further expands the possibilities for SLS applications in various industries.