Digital Manufacturing

Selecting a Material for Stereolithography (SLA) 3D Printing

Updated on Friday 12 August 2022, 2:29 PM

6 Minute Read

Many factors come into play when comparing the material properties of thermoplastics found in injection moulding versus “thermoplastic-like” materials used in an industrial-grade 3D printing technology like stereolithography (SLA).

SLA is a plastic 3D printing process that uses a thermoset liquid, not a thermoplastic, which is UV-cured in layers to form final parts. Because of this major difference in fabrication methods, material properties like tensile strength, heat deflection, and flexural modulus may differ from SLA’s more traditional counterpart. Furthermore, SLA produces anisotropic properties where the values for X, Y, and Z axes may differ depending on the orientation of the build—a consideration unique to 3D printing processes.

Within our 3D printing service, we offer a thorough selection of thermoplastic-like SLA materials, but what may surprise you is the versatility and range of potential applications for SLA parts. In the tables and charts below, we’ll take you through each material and its properties, and compare them with one another (as well as with moulded plastics) to help you decide how to best implement SLA.

 

Polycarbonate-Like Materials

PC-Like Advanced High Temp (Accura 5530) material is best used for parts that need strength and stiffness combined with high temperature resistance, such as under-the-hood automotive or electrical components. With a thermal post-cure, the part’s heat deflection can be improved even further, but at the expense of durability. Note that a thermal post-cure will transition the part colour to a slightly amber hue.

 

Ceramic-Like White Material

Often used for automotive housings, electrical casings, wind tunnel testing, and other components that require heat tolerance and strength. Combines superior high-heat tolerance with strength and stiffness. A thermal post-cure can be used to further improve mechanical properties and its heat resistance, however, it will be more brittle.

Chart 1: Two PC-like materials and one moulded PC thermoplastic are compared across four material property categories. *test speed 10mm/min.

ABS-Like Materials

ABS-Like Black (Accura Black SL7820) has high strength and good dimensional stability, even in high humidity. The material is black and commonly used in automotive parts, consumer packaging, electrical housings, and toys due to its impact resistance and ease of secondary finishing that provides the appearance of production quality.

MicroFine™ is an exclusive Protolabs material that can build ultra-fine features in micro resolution. MicroFine™ is available in a green or grey colour. Layer thicknesses of 0.025mm and feature sizes of 0.07mm are possible with MicroFine™ to accommodate applications that require parts that are generally less than a cubic inch in size.

ABS-Like Translucent/Clear (Somos Watershed XC 11122) is a strong, durable, low moisture absorption ABS-like material. It’s nearly colourless and mimics a clear engineering-grade plastic. Watershed’s high clarity makes it a perfect material for prototyping lenses, flow-visualisation models and microfluidics. Note that secondary operations will be required to get the material functionally clear. Watershed will also retain a very light blue hue afterward.

ABS-Like White (Accura Xtreme White 200) offers strength and durability, lending itself well to applications that require flexible snap-fit features. Note that ABS-Like White (Accura Xtreme White 200) has the lowest heat deflection of the SLA materials offered at Protolabs.

Chart 2: Four ABS-like materials and one moulded ABS thermoplastic are compared across four material property categories. *test speed 10mm/min.

True Silicone Material

Typically used in healthcare applications like prosthetics, ear plugs or wearables, as well in broader industries, e.g. automotive or mechanical engineering, for products like sealings, housings and gaskets. This material is biocompatible and has passed certifications in ISO DIN EN 10993-05 (Tests for in vitrocytotoxicity) and ISO DIN EN 10993-10 (Tests for irritation and skin sensitisation). The material shows high resistance to harsh environmental conditions, various acids, bases and non-polar solvents. The printed parts are water repellent, insulating and have a high gas permeability.

True Silicone in compared to LSR Elastosill Shores.
The different True Silicone shores available at Protolabs, and how they compare.

Comparison Charts for Material Properties

The charts below measure several thermoplastic-like materials suitable for SLA printing against various material properties: Tensile strength, elongation at break, water absorption, and e-modulus.

Tensile Strength

Elongation at Break

Water Absorption

E-Modulus

Parting Notes

Unlike thermoplastics, long-term exposure to UV light and moisture will alter the appearance and mechanical properties of SLA materials if they are not protected by plating or painting. Over time, you may experience part warpage, yellowing, and brittleness in some parts. SLA parts are not intended for long-term use in many instances, but understanding the short-term benefits of having highly detailed form and fit parts to use during early prototyping can be useful.

Remember to work closely with the 3D printing experts to help you select the right material for your project and ensure that build orientation is optimised for your part applications. Check out our 3D Printing Materials Guide for a broader view of additive materials, both plastic and metal, across all technologies.

Dive deeper into stereolithography at protolabs.co.uk. For questions on 3D printing or any of our services, please contact an applications engineer at customerservice@protolabs.co.uk or +44 (0) 1952 683047

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