Comparing injection-molded thermoplastics to ‘thermoplastic-like’ materials in stereolithography
Many factors come into play when comparing the material properties of thermoplastics found in injection molding versus “thermoplastic-like” materials used in an industrial-grade 3D printing technology like stereolithography (SL).
SL 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 flexure modulus may differ from SL’s more traditional counterpart. Furthermore, SL produces anisotropic properties where the values for X, Y and Z axis may differ depending on the orientation of the build—a consideration unique to 3D printing processes.
At Protolabs, a thorough selection of thermoplastic-like materials are offered through SL, but what may surprise you is the versatility and range of potential applications for SL parts. We’ll take you through each material and its properties, and compare them with one another (as well as with molded plastics) to help you decide how to best implement SL.
Accura 5530 material is transparent in color, temperature-tolerant and water-resistant. It also is resistant to automotive fluids, making it suitable for under-the-hood and electrical applications. Note that it requires secondary operations to achieve transparency and the final part will still retain a slight amber hue.
Accura 60 offers the ability for fine detail while providing good stiffness in parts. Common applications include durable prototypes for automotive, consumer electronics and lighting components, as well as medical instruments. Accura 60 has a high tensile strength and modulus, making this a good choice to replace polycarbonate (PC) when heat resistance is not critical. However, Accura 60 has the highest moisture absorption rate of the SL materials, which may impact dimensional stability over time.
Somos NanoTool has an added ceramic filler that increases stiffness and brittleness over other SL materials. Along with stiffness, Nanotool touts the highest temperature resistance compared to most materials offered in SL. It’s regularly used in aerospace and automotive applications that often require greater strength and temperature resistances.
|ACCURA 5530||ACCURA 60||SOMOS NANOTOOL||PC (MOLDED)|
|Hardness, Shore D||88||86||93-94||118-120 (R-scale)|
|Heat Deflection*||338-482 °F||127-131 °F||496-506 °F||250-280 °F|
|Tensile Modulus||3,585 – 3,758 MPa||2,690-3,100 MPa||10,400-11,400 MPa||2,400 MPa|
|Tensile Strength||47-61 MPa||58-68 MPa||66-80 MPa||50-72 MPa|
|Flexural Modulus||3,496-3,634 MPa||2,700-3,000 MPa||9,960-10,200 MPa||2,200-2,400 MPa|
|Flexural Strength||96-108 MPa||87-101 MPa||103-149 MPa||82-93 MPa|
Chart 1: Comparison of three PC-like materials and one molded PC thermoplastic across six material property categories. Notice how the heat deflection in the PC-like parts are much lower or have a wider range than the molded PC, due to the anisotropic properties. *Heat deflection was measured at 66 psi.
RenShape SL 7820 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 Green is a proprietary material at Protolabs, offering an extremely high resolution and build accuracy. MicroFine has a unique opaque green color distinguishing it from other materials. Layer thicknesses of 0.001 in. and feature sizes of 0.002 in. are possible with MicroFine Green to accommodate applications that require very small parts.
Somos Watershed XC 11122 is strong, durable, water-resistant ABS-like material. It’s nearly colorless and mimics a clear engineered-grade plastic. Watershed’s high clarity makes it a perfect material for prototyping lenses, flow-visualization models and micro-fluidic parts. Note that it requires secondary operations to get the material completely clear. Watershed will also retain a very light blue hue afterward.
|ACCURA ABS BLACK||MICROFINE GREEN||SOMOS WATERSHED||ABS (MOLDED)|
|Hardness, Shore D||87||85||—||109 (R-scale)|
|Tensile Modulus||2,000-2,500 MPa||2,100 MPa||2,650-2,880 MPa||2,200-2,500 MPa|
|Tensile Strength||39-51 MPa||45 MPa||47-54 MPa||32-42 MPa|
|Flexural Modulus||2,100-2,500 MPa||2,200 MPa||2,040-2,370 MPa||1,800-2,600 MPa|
|Flexural Strength||62-80 MPa||74 MPa||63-74 MPa||60-72 MPa|
Chart 2: Comparison of three ABS-like materials and one molded ABS thermoplastic across six material property categories.
Accura Xtreme White 200 is comparable to both a polypropylene (PP) and ABS thermoplastic in that it offers strength and durability, lending itself well to applications that require snap-fit features. Note that Xtreme White 200 has the lowest heat deflection of the SL materials offered at Protolabs.
Somos 9120 is translucent in appearance, providing excellent resolution and fine detail. You may want to consider Somos 9120 for parts with thin walls or small holes. The PC-like material is also the most flexible SL material at Protolabs, while also durable. Potential applications include automotive components, electrical housings and medical devices.
|ACCURA XTREME WHITE||SOMOS 9120||PP (MOLDED)|
|Hardness, Shore D||78-80||80-82||80-100 (R-Scale)|
|Tensile Modulus||2,300-2,630 MPa||1,227-1,462 MPa||1,720 MPa|
|Tensile Strength||45-50 MPa||30-32 MPa||27-40 MPa|
|Flexural Modulus||2,350-2,550 MPa||1,310-1,455 MPa||1,000-1,400 MPa|
|Flexural Strength||75-79 MPa||44-46 MPa||41 MPa|
Chart 3: Comparison of two PP-like materials and on molded PP thermoplastic across six material property categories. Notice that properties are fairly similar between each.
FineLine SLArmor uses DSM Somos NanoTool as a base material for 3D printing and has a secondary process that adds a thin metal coating that provides the look, feel and strength of a metal part without any added weight. SLArmor’s nickel plating adds strength and temperature resistance to SL parts that previously was not achievable. Note that we typically layer either 0.002 in. or 0.004 in. of plating thickness on parts.
|SLArmor 10% Metal Volume||SLArmor 20% Metal Volume||SLArmor 30% Metal Volume||Die Cast Aluminum|
|Tensile Strength||100 MPa||145 MPa||200 MPa||300 MPa|
|Elongation at Break||0.9%||1.04%||1%||2-5%|
|Mod. Of Elasticity||21,000 MPa||31,000 MPa||42,000 MPa||70,000 MPa|
Chart 4: Comparison of three grades of nickel-plated SLArmor and die-cast aluminum across four material property categories. Protolabs tests to ASTM D638M standards.
Unlike thermoplastics, long-term exposure to UV light and moisture will alter the appearance and mechanical properties of SL materials if they are not protected by plating or painting. Over time, you may experience part warpage, yellowing and brittleness in some parts. SL parts are not intended for long-term use in many instances, but the short-term benefits of having highly cosmetic and functional parts to use during early prototyping are highly beneficial.
Remember to work closely with the 3D printing experts to optimize build orientation, anisotropism and material properties. Adjusting the direction in which the part is built can often improve the material properties and clarity of the part.
Dive deeper into stereolithography at protolabs.com.
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2 Responses to “Product Feature: How 3D Printing Materials Measure Up”
Protolab appears to be the first to publish the character differences between injection grade molding material and 3D printing material (SL).
Out here most engineers think if it says ABS it means ABS, The SL industry should have labeled ABS “LABS” for “like”.
The use of these “L” materials is becoming problematic because the industry does not use “L” to signify that theses materials are “not” real ABS.
Most SL compound produces publish the ABS compound data as the actual “L” compound because they do not have the wherewithal to identify the actual “L” compound features, what a scam.
Most all “L” based material must have secondary processing chemistry removed with vary harsh “cleaning” chemistry and are not providing clear cleaning and hazardous instructions.
I know that the SL industry is not vary old compared to metal casting, but not providing factual material data because it is proprietary (don’t have the money to test material features) ignores users safety…
A useful article but with one general – important – remark. It describes stereolithography as a 3D-printing method but this is only one of the growing number of technologies to create unique 3D models. And if the focus is on materials then I can name laser sintering (SLS) and Fused Deposition Modeling (FDM) as examples of prototyping using the real material. For engineers it is getting to be a prime need to know about the different prototyping technologies and how to use them wisely.