Strongest 3D printer filament: types compared

Among the filaments a home printer can use, polycarbonate is generally the strongest all-round, and nylon is the toughest. But “strongest” has no single answer, because a part can fail by bending, snapping, softening in heat or splitting between layers, and no filament is best at resisting all four. PLA is stiffer than most people expect and useless in a hot car. PETG is weaker on paper and survives knocks that shatter PLA. The right question is what will break the part, and the answer picks the material.

Four kinds of strong

• Stiffness and tensile strength. How hard the part is to bend, and how much steady pull it takes before it breaks. This is the figure on most data sheets.
• Impact resistance (toughness). Whether the part survives being dropped or knocked. A tough material bends and dents; a brittle one snaps.
• Heat resistance. The temperature at which the part starts to soften and sag under load. A part that deforms in a warm car has failed, however strong it was on the bench.
• Layer adhesion. How well each printed layer bonds to the one below. Every filament print is weakest between its layers, and some materials bond far better than others.

Published figures for any of these vary by brand and by how the test piece was printed, so the comparisons below are relative, not laboratory values.

The filament types, one by one

PLA

The default material, and stiffer than its reputation. Plain PLA is among the most rigid of the common filaments and takes a high steady load for its price. Its two failings are that it is brittle, so it snaps rather than bends, and that it softens at around 55 to 60 °C. Strong on a shelf; weak in sunlight, in a car or under impact. PLA ranked by £/kg.

PLA+ (Tough PLA, PLA Pro)

PLA modified to be less brittle, with better layer bonding. It gives up a little stiffness for a useful gain in impact resistance and prints as easily as PLA. The heat limit is unchanged. The recipe varies by brand, so the improvement does too. PLA+ ranked by £/kg.

PETG

Less stiff than PLA, but much tougher: it flexes and deforms before it breaks. Layer adhesion is very good, it holds up to around 75 °C, and it copes with moisture and sunlight better than PLA. For brackets, clips and outdoor parts it is the practical step up, and it needs no enclosure. PETG ranked by £/kg; see also PLA vs PETG.

ABS and ASA

Tough, and usable to roughly 100 °C, which is why ABS is used for car interior trim and power tool housings. ASA behaves much the same and adds resistance to sunlight, so it is the usual choice for outdoor parts. Both shrink as they cool, which causes warping and split layers unless the printer is enclosed, and both give off stronger fumes than PLA or PETG and need ventilation. ABS and ASA ranked by £/kg.

Nylon (PA)

The toughest of the common filaments. Nylon resists impact, fatigue and wear exceptionally well and has excellent layer adhesion, which makes it the material for gears, hinges and parts that are flexed repeatedly. It is not especially stiff: thin nylon parts bend. It also absorbs moisture readily, which makes it harder to print and changes its properties, so it must be dried before use. It needs high nozzle temperatures and prints best enclosed. Nylon ranked by £/kg.

Polycarbonate (PC)

Generally the strongest all-round filament available for desktop printers: high tensile strength, outstanding impact resistance and heat resistance well above 100 °C. It is also the hardest of this list to print, needing a very hot all-metal hotend, a hot bed and an enclosure, and it absorbs moisture. Many filaments sold as PC are blends made easier to print, with somewhat lower properties. PC ranked by £/kg.

Carbon fibre and glass fibre blends

Chopped fibres added to any of the above make the part stiffer and more stable in size. They do not make it tougher, and usually make it more brittle. Nylon-CF is the notable combination: nylon's toughness and heat resistance with the stiffness plain nylon lacks. All of them need a hardened nozzle. See carbon fibre filament explained.

TPU

Flexible rather than strong in the usual sense, but worth a mention: because it stretches instead of cracking, a TPU part is very hard to break. If the job is absorbing shocks, it is the answer. See printing with TPU.

Compared side by side

Which to pick

How you print it matters as much as what you print

A well-printed PETG part is stronger than a badly printed nylon one. Before changing material, check the settings that decide strength:

• Orientation. Parts are weakest between layers. Turn the model so the main load runs along the printed lines, not across the layer joins. This one change often matters more than the material.
• Walls before infill. Extra perimeters add more strength than extra infill. Going from two walls to four does more than raising infill from 20 to 50 per cent on most parts.
• Temperature and cooling. Layers bond better printed a little hotter and with less fan. Too much cooling on PETG, ABS or nylon gives weak layers.
• Dry filament. Damp filament prints weak and bubbly, nylon and PETG especially. See do you need a filament dryer?
• A wider line. A larger nozzle lays thicker lines with more contact between layers. See nozzle sizes explained.

The practical order for most people: PLA or PLA+ first, PETG when a part breaks or gets warm, ASA for the car and the garden, and nylon or polycarbonate only when a specific part demands it and the printer can cope. Compare every type on the filament price list.

Questions people ask

What is the strongest 3D printer filament?

Polycarbonate is generally the strongest all-round filament for desktop 3D printers, combining high tensile strength, very high impact resistance and heat resistance above 100 degrees Celsius. Nylon is the toughest, resisting impact, fatigue and wear better than anything else in common use. Both are hard to print, needing high temperatures, dry filament and preferably an enclosure.

Is PLA a strong filament?

PLA is strong in one sense and weak in two. It is among the stiffest common filaments and takes a high steady load, which surprises people. However, PLA is brittle, so it snaps under impact rather than bending, and it softens at around 55 to 60 degrees Celsius, so it fails in a hot car or direct sun.

What are the main types of 3D printer filament?

The main types of 3D printer filament are PLA, PLA+, PETG, ABS, ASA, TPU, nylon and polycarbonate, plus carbon fibre or glass fibre filled versions of these. PLA is the easy default, PETG is the tougher all-rounder, ABS and ASA handle heat and outdoor use, TPU is flexible, and nylon and polycarbonate are engineering materials for demanding parts.

Which filament is best for parts that take impacts?

Nylon is the best common filament for parts that take impacts, followed by polycarbonate, ABS, ASA and PETG. These materials bend or dent before they break, where PLA snaps. For most home printers PETG is the practical choice, because it is far tougher than PLA and prints without an enclosure.

Which 3D printer filament is best for heat resistance?

Polycarbonate has the best heat resistance of the common 3D printer filaments, staying usable well above 100 degrees Celsius. ABS and ASA hold their shape to roughly 100 degrees, PETG to around 75, and PLA only to about 55 to 60. For parts in a car, ASA or ABS is the usual choice.

Is nylon stronger than PETG for 3D printing?

Nylon is tougher and more wear-resistant than PETG, with better layer adhesion and fatigue resistance, which makes it the better material for gears, hinges and heavily used parts. It is not much stiffer, and thin nylon parts flex. Nylon is also much harder to print, because it must be dried, needs higher temperatures and prints best in an enclosure.

How do I make a 3D print stronger without changing filament?

The most effective way to make a 3D print stronger is to orient it so the main load runs along the printed lines rather than across the layers. After that, add more walls, which helps more than adding infill, print slightly hotter with less cooling to improve layer bonding, and make sure the filament is dry. A well-printed part in an ordinary material beats a badly printed one in a strong material.