FDM Materials Guide: PLA, ABS, ASA, PETG & TPU Compared

Choosing the right FDM material is the single most important decision in part design. It determines whether your prototype will fail from the get-go or even has a chance at success.

This guide covers the five FDM filaments we run most often at Simple Machining: PLA, ABS, ASA, PETG, and TPU. For each, we cover the properties that matter for engineering work, where the material excels, where it fails, and the parts we'd quote it on. At the end: a side-by-side comparison and decision framework to help you spec the right material the first time.

PLA

PLA (polylactic acid) is the most-printed FDM filament, and for good reason. It prints reliably on virtually any FDM machine, holds fairly tight tolerances, and produces a clean surface finish without a heated chamber. Tensile strength is competitive with other commodity thermoplastics at roughly 50 to 60 MPa, and stiffness is high. PLA, however, is brittle and softens at relatively low temperatures.

PLA's glass transition is roughly 60 °C, confirmed across major manufacturer datasheets like Polymaker's PLA grades. A part left in a closed car on a summer day will deform. It also creeps under sustained load and degrades under UV exposure. For prototypes, mockups, indoor fixtures, and parts that will never see heat or sun, PLA is the right call. For functional load-bearing parts in any thermally active environment, it may not be the best choice.

Best applications:

• Concept models and visual prototypes
• Indoor jigs, fixtures, and tooling
• Low-stress mounting hardware and brackets
• Investment casting patterns (PLA burns out cleanly)

Avoid for: outdoor parts, vehicle interiors, snap-fit features that flex repeatedly, parts subject to impact loading.

We run PLA on most autoquoter jobs where the customer wants a fast, low-cost prototype to validate fit. If the part needs to be load-bearing, we usually steer toward ABS or PETG.

ABS

ABS (acrylonitrile butadiene styrene) is the default plastic for automotive interior trim, consumer electronics housings, and Lego bricks. It handles heat and impact far better than PLA, with a glass transition near 105 °C and excellent toughness. Tensile strength sits around 35 to 45 MPa, but the real value over PLA is impact resistance and thermal performance. ABS also accepts acetone vapor smoothing for a glossy, near-injection-molded surface finish.

There are tradeoffs however. ABS is more difficult to print, as it can warp without a heated bed and enclosed chamber, and it emits styrene fumes that can be toxic and require adequate ventilation. Bridges, support structures, and overhangs are harder to clean up than with PLA. For parts that will live indoors and need toughness, ABS is excellent. For anything that sees sunlight, ABS can yellow and embrittle within a few months.

ABS is the right call for indoor enclosures, automotive interior parts, tool handles, and impact-resistant brackets. We run it routinely for low to mid-volume production where customers need better mechanical properties than PLA can deliver.

ASA

ASA (acrylonitrile-styrene-acrylate) was developed specifically to address ABS's UV problem. The acrylate group replaces butadiene, giving the material the same toughness and similar thermal performance with dramatically better weatherability. ASA parts hold their color and mechanical properties for years in direct sun. Print behavior is nearly identical to ABS: an enclosed chamber is recommended, a heated bed is required, and adequate ventilation is expected.

If a part will ever be exposed to outdoor conditions, a vehicle exterior, or any UV-rich environment, ASA is the right choice. We use ASA for outdoor enclosures, signage components, and drone or robotics parts that operate in sunlight. The cost premium over ABS is modest, and the longevity payoff is significant.

PETG

PETG (polyethylene terephthalate glycol) sits between PLA and ABS on almost every axis: easier to print than ABS, tougher than PLA, more chemically resistant than either. Tensile strength is around 45-55 MPa, with notably better elongation at break than PLA, meaning parts bend before they shatter. The glass transition is around 80 °C.

PETG also has practical advantages that engineers underestimate. It prints without warping on most open-frame machines and resists a wide range of solvents and weak acids. However, layer adhesion can be inconsistent if temperatures drift during printing, and the surface is grippy, which complicates support removal on detailed geometry.

We use PETG when:

• The part needs more toughness than PLA, but ABS is overkill
• Light chemical exposure is part of the use case (mild solvents, oils, non-regulated food contact)
• The customer wants strength and printability without ABS's chamber requirements

PETG is also a strong default for low-volume production runs where consistency across many copies matters more than peak mechanical performance.

TPU

TPU (thermoplastic polyurethane) is the only flexible filament most engineers will need. Hardness is specified on the Shore A scale; the most common grade we run is TPU 95A, firm but flexible, comparable to a hard rubber. Softer grades like 85A exist for higher elasticity but are slower to print and less dimensionally stable.

The strengths are exactly what you'd expect: high elongation at break (often 400 percent or more), excellent abrasion resistance, and good chemical resistance against oils and many solvents. Common applications include gaskets, seals, vibration dampers, protective bumpers, hose end caps, custom grips, and wearable components.

TPU prints slowly, typically 20 to 30 mm/s, because the flexibility that makes it unique also makes it harder to feed through a Bowden extruder. Bridging will leave more surface marks and small-feature accuracy is below what PLA or PETG can deliver. TPU is best used for anything that needs to be compressed, flexed, or sealed. In terms of flexible materials, it's the only FDM option.

FDM Material Comparison

Typical ranges for engineering-grade filaments. Values vary by manufacturer and print settings.

PLA vs ABS

The PLA vs ABS comparison is the most common question that comes up on almost every project. The short version: PLA wins on print quality, dimensional accuracy, and speed. ABS is much better suited for applications requiring toughness and heat resistance. If the part is a prototype that lives on a desk or a fixture used briefly in a controlled environment, PLA is generally faster and cheaper. If the part will see mechanical load, repeated handling, or temperatures above 50 °C, ABS is likely worth the extra cost.

ABS vs ASA

ABS and ASA are nearly identical in mechanical performance and processing. The only meaningful difference is UV and light chemical resistance. If your part stays indoors, ABS is the cost-effective choice. If it sees any UV exposure, even through a window over time, ASA pays for itself by lasting longer without yellowing or embrittlement.

How to Choose the Best FDM Filament

The framework below covers most cases. For edge cases, send the part geometry and use case to our CAD design team, and we'll recommend a material with reasoning.

Start with the operating environment

Indoors, climate-controlled, no UV: PLA, ABS, or PETG depending on toughness needed. Outdoors or UV-exposed: ASA. Above 60 °C: ABS, ASA, or skip FDM for a higher-temperature process. Wet or chemically aggressive: PETG for mild exposure, talk to us for harsh chemistries.

Then check the load case

Low-stress fixture or visual model: PLA. For repeated handling, snap fits, drops/impacts: ABS, ASA, or PETG. Use TPU for applications where the part will see flexing, sealing, or compression. For much higher structural-load applications, consider SLS or MJF instead of FDM.

Finally, consider production constraints

Tight budget, fast turnaround, high quantity: PLA. Mid-volume production with consistent quality: PETG. Customer-facing finished surfaces: ABS with acetone smoothing, or ASA for outdoor.

For more on how part geometry and infill affect strength regardless of material, see our guide to FDM infill patterns.

Engineering and Specialty Materials

Beyond the five core filaments, we run PLA-CF (carbon fiber reinforced PLA) on the autoquoter for parts that need higher stiffness than standard PLA at similar cost and lead times. Nylon (PA6, PA12) and other engineering filaments are available through manual quote. For chemical resistance, fatigue performance, or properties beyond the core five, send us the part details and we'll scope it.

For specialty engineering materials like ULTEM (PEI) and polycarbonate (PC), typically used in aerospace, high-temperature, and flame-retardant applications, reach out with your part requirements and target performance, and we'll scope the project end-to-end.

Conclusion

FDM gives you a wide spectrum of mechanical and environmental performance, but only if you match the material to the use case. Default to PLA for prototypes, ABS or ASA for toughness and heat resistance, PETG for balanced production parts, and TPU for anything flexible. Spec the material against the part's real environment, not against habit.

If you have a part you're not sure about, upload your STL or STEP file to our 3D printing service for an instant quote, or send us your requirements and we'll help you choose the right material.

Frequently Asked Questions

What is the strongest standard FDM material?

For tensile strength, PLA leads at 50 to 60 MPa, but raw tensile strength is rarely the right metric. For impact resistance and toughness, ABS, ASA, and PETG all outperform PLA. For high-performance engineering parts, glass-filled or carbon-fiber-reinforced filaments like PLA-CF and PA-CF surpass commodity filaments and approach injection-molded performance.

Which FDM material is best for outdoor use?

ASA is the right choice for any outdoor application. It has the toughness of ABS plus excellent UV stability, holding its color and mechanical properties for years in direct sunlight. PETG is a workable second choice for short-term outdoor exposure but will degrade faster than ASA over multi-year deployments.

Can FDM parts be used for end-use production?

Yes. We run end-use FDM production regularly. The keys are choosing a production-grade material (PETG, ABS, or ASA), validating with a small batch first, and pricing per-part economics against injection molding. FDM beats molding under roughly 500 to 1,000 units for most parts; above that, the math usually favors a tooled process.

Is PETG stronger than PLA?

PETG and PLA are similar in tensile strength, with PLA often slightly higher in pure pull tests. PETG is meaningfully tougher: it elongates more before breaking, handles impact better, and survives heat that would deform PLA. For functional parts, PETG is usually the stronger choice in practical terms.

How do I choose between FDM and other 3D printing processes?

FDM is the right call for cost-sensitive prototypes, larger parts, and end-use production with engineering thermoplastics. SLA wins on detail and surface finish for visual models. SLS and MJF win for complex geometries and isotropic strength without supports.

By: The Simple Machining Team

Simple Machining is a Bay Area on-demand manufacturer specializing in 3D printing, CNC milling, and CAD design for engineers and product teams. We work with startups and SMBs across the US to deliver fast-turn, high-quality parts with no minimum order quantities.

Disclaimer

The content appearing on this webpage is for informational purposes only. Simple Machining makes no representation or warranty of any kind, be it expressed or implied, as to the accuracy, completeness, or validity of the information. Any performance parameters, geometric tolerances, specific design features, quality and types of materials, or processes should not be inferred to represent what will be delivered by Simple Machining. Buyers seeking quotes for parts are responsible for defining the specific requirements for those parts. Please refer to our terms and conditions for more information.