Why is that? Well, it\u2019s true that most standard resins are relatively brittle compared to other\u00a03D printing materials<\/a>\u00a0and aren\u2019t recommended for stressed parts or outdoor use, although there are tough and durable resins on the market specifically formulated for stronger applications, and they can be really strong.<\/p>\n In this article, we\u2019ll\u00a0look more into these tough 3D printing resins and show you just how\u00a0strong they can really be.<\/p>\n While\u00a0FDM 3D printing<\/a>\u00a0technology can use traditional industrial plastics like\u00a0ABS<\/a>\u00a0and\u00a0polycarbonate (PC)<\/a>, resin 3D printers require special photopolymer resins that harden (cure) under UV light. Most 3D printing resins are either epoxy-based or acrylate-based, the latter being used more often in desktop printers.<\/p>\n A lot of people think of resin 3D printed parts as fragile and most suitable for ornamental and prototyping applications rather than functional and load-bearing components. But this is only true if the resin isn\u2019t properly selected. That being said, if you\u2019re buying a generic resin for a tough job, it won\u2019t give you the strength that you\u2019re looking for.<\/p>\n Examples of super-strong resin can be found in a wide variety of industries. There are\u00a0castable resins\u00a0for\u00a0making jewelry and\u00a03D printing in the field of dentistry<\/a>\u00a0to produce mouth guards, crowns, and surgical guides. There are also high-temperature resins that are suitable for different industrial applications and even\u00a0resins that can produce rubber-like parts<\/a>.<\/p>\n Let\u2019s turn our focus to the strongest resins available and find out how tough they actually are compared with other FDM 3D printing materials.<\/p>\n Let\u2019s start by briefly going over a mechanical property that strongly relates to material strength. Tensile strength is defined as the maximum stress that a certain material can withstand while being stretched before breaking.<\/p>\n As the definition suggests, tensile strength values are usually measured by a pull test that follows strict international procedures, so the results can be used worldwide. The higher the tensile strength, the stronger the material is considered to be because of how much stress it can withstand.<\/p>\n Now, for the resins. First, let\u2019s look at how standard 3D printing resins compare to resins marketed as tough. Then, we\u2019ll compare these tougher resins to common FDM materials like\u00a0ABS<\/a>,\u00a0PLA<\/a>, and\u00a0PETG<\/a>.<\/p>\n The standard resin selected as our\u00a0reference\u00a0was\u00a0Anycubic\u2019s colored UV resin<\/span>\u00a0since their\u00a0Photon series of printers<\/a>\u00a0is one of the most popular on the market.<\/p>\n From the graph above, it\u2019s clear how much stronger the tough resins are compared to the standard. In fact, the three resins that are chosen for this comparison \u2013 the\u00a0Formlabs Tough 2000<\/span>,\u00a0eSun\u2019s Hard-Tough<\/span>, and\u00a0Siraya Tech\u2019s \u201cBlu\u201d<\/span>\u00a0\u2013 show almost double the tensile strength compared to Anycubic\u2019s resin. (Formlabs\u2019 tough resin line, including the 2000, is proprietary and can only be used with the\u00a0latest Formlabs printers.)<\/p>\n Just because the resin is tough, it doesn\u2019t mean that prints made from these resins will be twice as strong as if they were printed with a standard resin. Other factors like model design and print settings play important roles in the final print\u2019s strength, which we\u2019ll discuss in more detail later.<\/p>\n Nonetheless, comparing tensile strength is a straightforward way to determine which material is stronger, and from the numbers supplied by the manufacturers, it\u2019s clear that these resins are much tougher than the standard. But how do these tough resins hold up against other plastics used by FDM 3D printers?<\/p>\n To answer this question, we\u2019re turning to Stefan Herman from the\u00a0CNC Kitchen YouTube channel<\/a>, who has developed a testing method in which a 3D printed hook is stretched until breakage, simulating a tensile strength pull test.<\/p>\n Stefan\u2019s been consistently testing different materials with this method, and the results are shown in the graph above.\u00a0 In a\u00a0video where he tests the Siraya \u201cBlu\u201d resin<\/a>, Stefan found that Siraya\u2019s tough resin was stronger than some FDM materials like ABS and ASA.<\/p>\n Although the material properties greatly determine the toughness of a given print, there are other important factors that can affect mechanical performance.<\/p>\n The way a print is designed greatly influences its strength. For example, a certain component can be strengthened by allocating more material to the regions where stress will be concentrated. The design freedom allowed by 3D printing means computational tools like\u00a0topology optimization<\/a>, which\u00a0automates this process, are frequently used.<\/p>\n The way the part is fabricated also relates to how well it can withstand external forces. In a 3D printing context, this is determined by the printing settings defined during slicing. It\u2019s well known that larger layer heights have a\u00a0strong influence on FDM\u2019s part strength<\/a>, and this is also true for resin 3D prints.<\/p>\n While it\u2019s a fairly common procedure in resin printing to hollow models in order to save material, this doesn\u2019t apply to functional parts. Most\u00a0FDM slicers<\/a>\u00a0include several infill density and pattern options to reduce material and printing times, yet these are rarely seen in\u00a0slicers for resin printing<\/a>. Still, third-party slicer\u00a0ChiTuBox<\/a>\u00a0does include these features, which provide the possibility of increasing toughness while still optimizing material usage.<\/p>\n Anisotropy is when an object or material\u2019s physical property has a different value when measured in different directions. This happens in 3D printing when objects printed by FDM technology display varying physical properties depending on the part\u2019s build direction. More specifically, lower adhesion is created between layers on the Z-axis, which causes a lower pull strength when compared to the X- or Y-axis. As you can see in the image above, when weight is applied to an FDM print that isn\u2019t oriented or modeled in such a way that takes anisotropy into account, it can break.<\/p>\n When it comes to resin printing, however, the opposite is true because resin is isotropic. During his testings with Siraya\u2019s Blu, Stefan Herman verified this by showing experimentally that the parts are equally strong regardless of the build direction. Formlabs also came to the same conclusion, which is discussed in their\u00a0article about SLA printing\u2019s isotropic property<\/a>.<\/p>\n Given all that we\u2019ve learned, we hope it\u2019s clear that by choosing the right resin, SLA 3D printing can produce prints just as strong as FDM can.<\/p>\n To illustrate this conclusion, here\u2019s an inspiring example of how resin can produce strong, functional, and detailed parts in the world of orthotics. You can also check out our article on the\u00a0most promising orthotics projects<\/a>.<\/p>\n Slovenian Matej Vla\u0161i\u010d\u2019s son Nik was born with cerebral palsy and couldn\u2019t stand or walk without assistance. Mr. Vla\u0161i\u010d created custom-made ankle-foot orthoses (AFOs) for Nik and used a Formlabs resin 3D printer to print them into reality. After around a year of development, the final design allowed Nik to walk within a few days.<\/p>\n Like many orthotic devices, AFOs must be strong enough to provide support while withstanding the full body\u2019s weight during motion. Mr. Vla\u0161i\u010d used\u00a0Formlabs\u2019 durable resin<\/span>, which proved to be both tough and comfortable, even for long periods of usage.<\/p>\n From this success, Mr. Vla\u0161i\u010d founded the company\u00a0Animake<\/a>. He and his team provide diagnostic treatment and 3D printed orthotic devices that help other children in need of custom AFOs.<\/p>\nStrong but Sweet<\/h3>\n
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Strength in Numbers<\/h3>\n<\/div>\n<\/div>\n
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Standard vs. Tough Resins<\/strong><\/h3>\n
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Tough Resins vs. FDM Materials<\/strong><\/h3>\n
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More Than Material<\/h3>\n
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Design & Geometry<\/strong><\/h3>\n
3D Printing Parameters<\/strong><\/h3>\n
Anisotropic vs. Isotropic<\/strong><\/h3>\n
Hard Stuff<\/h3>\n<\/div>\n<\/div>\n
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