Acrylonitrile Butadiene Styrene (ABS) and Polyethylene Terephthalate Glycol-modified (PETG) are two of the most commonly used engineering-grade thermoplastics in Fused Deposition Modeling (FDM) 3D printing. The choice between them often comes down to their mechanical strength, as users seek durable and functional parts. ABS is a long-established material known for its toughness and use in consumer products like LEGO bricks. PETG, a modified version of the plastic used in water bottles, has rapidly gained popularity as a strong, versatile alternative. Evaluating which is “stronger” requires a detailed look at how each material behaves under different types of stress and environmental conditions.
Comparing Mechanical Performance
The term “strength” in plastics is complex and depends heavily on the type of force applied, making a simple comparison difficult. When considering the force required to pull the material apart, known as tensile strength, PETG generally holds a slight advantage over ABS. PETG typically exhibits a tensile strength around 50 to 55 megapascals (MPa), while ABS usually registers closer to 40 to 42 MPa. This suggests that PETG can handle a marginally heavier static load before the material itself yields and breaks.
However, ABS is recognized for its higher rigidity and ability to withstand compressive forces, making it suitable for parts that need to maintain their shape under significant, sustained pressure. The true difference in part strength often comes down to how the material handles sudden impact or shock. PETG is inherently less brittle than ABS and possesses greater flexibility, allowing it to absorb impact energy by deforming slightly rather than cracking immediately.
The most significant factor influencing the final strength of a 3D printed object is the layer adhesion between successive layers of extruded filament. PETG is superior in this regard, bonding its layers exceptionally well, which minimizes the risk of delamination when force is applied perpendicular to the print orientation. ABS prints, particularly those created without a heated enclosure, are highly susceptible to layer splitting, which drastically reduces the part’s overall functional strength. Therefore, PETG’s excellent layer fusion often translates to a stronger final object that resists splitting under real-world stress.
Ease of Printing and Necessary Equipment
The printing process itself represents a major divergence between these two materials, significantly influencing the accessibility and reliability of the final part. ABS is notorious for its high thermal requirements and tendency to warp, a phenomenon caused by the material shrinking significantly as it cools. To mitigate this shrinkage and prevent the corners of a print from lifting off the build plate, a constant high temperature is required.
Successful ABS printing necessitates a heated build plate operating between 90°C and 120°C, along with a fully enclosed print volume to maintain a stable, warm ambient temperature. Without an enclosure, the rapid cooling of the print can lead to severe warping and poor layer adhesion, compromising the part’s mechanical integrity. ABS also emits strong, potentially harmful fumes during extrusion, which mandates the use of proper ventilation or a filtered enclosure for safe operation.
PETG is considerably more forgiving and accessible for a wider range of 3D printers, generally exhibiting minimal warping or shrinkage. It usually requires a heated bed set lower, typically between 60°C and 80°C, and an enclosure is optional rather than mandatory. This minimal warping allows for the reliable production of large or dimensionally accurate parts. The primary printing challenge with PETG is its extremely sticky nature, which can lead to excessive stringing if retraction settings are not carefully tuned. Its strong adhesion to the build plate, while great for preventing lifting, can sometimes make removing the finished print difficult and potentially damage the build surface.
Heat and Chemical Endurance
Beyond mechanical forces, the environment in which a part is used dictates the required endurance against heat and chemical exposure. ABS offers superior thermal resistance compared to PETG, maintaining its form at higher temperatures. The glass transition temperature (Tg) for ABS is typically around 100°C to 105°C, meaning it begins to soften and lose rigidity at this point.
PETG has a lower thermal tolerance, with its glass transition temperature around 80°C, making it less suitable for applications near high heat sources, such as car interiors on a hot day. If the printed part must operate under load in a high-temperature environment, the higher heat deflection temperature of ABS provides a distinct advantage.
In terms of chemical exposure, PETG is generally more resistant to a wider range of solvents, oils, and cleaning agents. This makes it a preferred choice for containers or parts that will be in contact with various household chemicals. Conversely, ABS is vulnerable to certain chemicals, most notably acetone, which can dissolve the material. While this vulnerability allows for post-processing techniques like acetone vapor smoothing, it also means the part will degrade if exposed to that solvent. PETG also demonstrates better stability when exposed to ultraviolet (UV) light and is less prone to yellowing or becoming brittle outdoors.
Selecting the Right Filament for Your Project
The decision between PETG and ABS ultimately depends on balancing the specific demands of the final application with the practicalities of the printing process. If your project requires the highest possible resistance to sustained heat or needs to be finished using solvent-based smoothing techniques, ABS is the appropriate choice. ABS is also favored when maximum material rigidity and compression strength are required for a part.
PETG should be selected if the primary requirements are high impact resistance and overall part robustness in a real-world setting, thanks to its superior layer adhesion and flexibility. PETG is also the preferred material for parts that will be exposed to UV light or chemical agents, or when the ease of printing is a major factor. Its low-fume emission and minimal warping make it a more beginner-friendly and convenient material to work with.