PLA vs ABS: What 3D printer filament should you use? We explain the differences and the fields of application of ABS and PLA Filament.
There are two materials a 3D printer using FDM (Fused Deposition Modeling) technology can process: ABS and PLA. Both are thermoplastics. That means they become malleable when heated – this way, you can shape them while they are heated, and they keep their (new) shape when cooling down. Both materials are available as filaments that you feed into your FDM 3D printer. The printing process for these materials is very similar.
However, both materials differ in a number of ways. Some FDM 3D printers only use PLA filaments while others can process either material.
This guide describes
- the main differences between the two materials,
- their advantages and disadvantages,
- and their fields of application.
PLA and ABS Explained in a Nutshell
PLA (PolyLactic Acid) is a biopolymer, i.e., a biodegradable plastic. It is made from renewable raw materials such as cornstarch or sugarcane. Aside from 3D printing, it is typically used for packaging material, plastic wrap, plastic cups and plastic water bottles. It is considered to be more ecologically friendly than ABS – after all, it’s made from plants.
ABS (Acrylonitrile-Butadiene Styrene) is an oil-based plastic. It is a tough material that can be used to create robust plastic objects for everyday use, for example in cars, electrical equipment or even in the popular Lego bricks.
The Main Properties of PLA and ABS Compared
PLA vs ABS Filament: Thermal properties
The diagram shows the thermal properties of PLA & ABS:
What do the technical terms in the diagram mean?
- The melt volume index (or melt flow index) is a measure of the ease of flow of the melt of the polymer. It is measured as the amount of material flowing in 10 minutes through a capillary of a defined diameter and length.
- The glass transition temperature (or glass point) is the point at which a hard and brittle (glassy) material transitions into a molten or rubber-like state when the temperature is increased. This value matters when you print something you plan to pour hot water or beverages in: When you print a coffee mug using PLA, the bottom sags when you pour in coffee that is hotter than 60ºC. Why ABS is no good idea either: See the “Recommended fields of application” section below.
- The slumping temperature indicates the heat resistance limit: At temperatures above this value, the object will be distorted. When your printer has a heated bed, the heated bed temperature must be below the slumping temperature; otherwise, the object will deform.
- The melting temperature (or melting point) is – obviously – the temperature at which the material starts melting.
- The 3D printing temperature is usually higher than the melting point as you want the filament to be molten (and not just starting to melt) when pressing it through the printer nozzle.
PLA vs ABS Filament: Mechanical and physical properties
PLA is more brittle and has a higher surface hardness. It is more prone to break when bent. Objects made from this material can be cut, filed, sanded, painted, and bonded using adhesives; treating them with acetone (for improving surface smoothness) is not possible.
When printed at the temperature recommended by the filament producer, ABS exhibits a superior layer bond. Objects 3D printed this way will be stronger and more impact-resistant. Therefore, it is better suited for mechanical parts and for objects that need to be weatherproof. Moreover, ABS parts are more flexible than PLA parts and tend to bend rather than break when under pressure. Also, ABS is better malleable, postprocessing is easier: The printed object can be cut, filed, sanded, painted, and bonded. And they can be treated with acetone to get a smooth and shiny surface or to weld two objects together.
PLA vs ABS Filament: Ease of printing
Overall, PLA is better suited for 3D printing beginners. ABS is more susceptible to typical 3D printing problems such as warping (i.e., the first layers cool down quicker and shrink, which causes the lower parts of the model to bend up at the edges). Printing ABS requires a bit of experimenting to find out the optimal settings.
PLA is more prone to clogging or jamming the printer nozzle: It is more sticky and expands more when melting. We recommend you painstakingly follow the printer manufacturer’s directions to avoid clogging the nozzle. There is almost no shrinkage when the printed layers cool down – so, warping and cracking layers are not an issue, the printed object can be removed more easily from the print bed than when using ABS. A heated bed is not required (but can improve print quality if used correctly), enclosing the printer is not required either (but again: the results will be better). To improve print bed adhesion we recommend covering the print bed with masking tape (also known as painters tape).
ABS is printed at higher temperatures than PLA, which greatly reduces the danger of clogging or jamming the nozzle. Moreover, it requires less pressure when feeding the filament to the nozzle. As ABS tends to shrink when cooling, the printed parts may exhibit warping, and layers may crack or split (especially in high objects). To avoid this, using a heated bed is a must; an enclosed case improves print quality as it protects the printed object from breezes. Stringing and large retractions are usually no problem. Adhesion to the print bed is weaker than when using PLA – this can result in a number of printing problems. To improve bed adhesion, we recommend covering the print bed with Kapton tape. That is twice as expensive as masking tape but stands temperatures up to 400ºC. Alternatively, you can apply hairspray to the print bed before starting a print job.
PLA vs ABS Filament: Storage
Both filaments (PLA/ABS) tend to absorb moisture from the air. To prevent that, the filament rolls are sealed when sold. Filament producers recommend to use up opened filament rolls rather sooner than later – otherwise, the print quality may suffer. We recommend storing filament rolls in a dry place.
When PLA is exposed to air for a longer time, you may notice bubbles and spurts at the printer nozzle during printing. This may clog the nozzle and reduce the surface quality of the printed object. It may also suffer from discoloration. Though humid PLA can be dried using warm air, the heating may alter the crystallinity ratio in it and change the thermal properties of the filament which will impact the printing temperature.
When printing slightly humid ABS, there may also be bubbles and spurts at the nozzle. Usually, there is no discoloration. Drying it with hot (but not too hot) air, e.g. using a food dehydrator normally does not impact the thermal properties of the filament.
PLA vs ABS Filament: Fumes and smell
When printing polymer filaments (PLA/ABS), you will notice some smell. That depends on the material used and the printing temperature.
PLA smells somewhat sweet, like waffles or candy when heated.
ABS, when heated, gives off a bad plastic smell. Some people report headaches and nausea from 3D printing. We recommend proper ventilation in enclosed areas.
PLA vs ABS Filament: Degradability and durability
PLA is biodegradable – after all, it is made from plant material. As it needs some heat to degrade, you can put it in the city compost but is not recommended to put it in your backyard compost.
ABS is not biodegradable but can be easily recycled.
Over time, both materials (PLA/ABS) degrade under sunlight or moisture. ABS is more stable and resistant to chemicals than PLA, however.
PLA vs ABS Filament: Choice
Both filaments can be bought in a wide variety of colors; there are even translucent filaments. Some special filaments are only available as a mix of PLA and other materials (usually milled), e.g. wood, bamboo or metal fill (brass, copper, bronze). Dutch filament producer ColorFabb has a fine selection of special filaments.
PLA vs ABS Filament: Prices
Prices for the prices of both filaments are more or less identical. Special filaments, e.g. PLA filaments mixed with wood or other materials, are more expensive.
PLA vs ABS Filament: Recommended fields of application
PLA is widely used in 3D printing, e.g. for household items, gadgets, and toys. It is better suited when flexibility is not your major requirement as it is more prone than ABS to break under pressure. On the other hand, it is biocompatible with the human body and can be used for objects that are worn on the skin.
Due to its relatively low glass point, PLA is unsuitable for objects that are subject to heat: When exposed to 60ºC or more for some time, it loses its shape. You wouldn’t use PLA for objects that are exposed to direct sunlight for a prolonged time or that are placed in a car. It is also not suitable for kitchen equipment that is put into the dishwasher (at least not for dishwasher programs at 60ºC or more).
ABS is better suited for objects that need to withstand rough usage, hot environments, that need to be weather-proof, that may be dropped or have to be bendable. It can be used for parts that are subject to mechanical stress, for interlocking parts or pin-joints.
ABS is not considered to be a food-safe material: Especially when the material gets in contact with hot liquids or warm food, chemicals from the plastic will leach out into the liquid or food over time. To seal the surface, you need to post-process it using solvent polishing or painting that is food-save.
Header image from Filamentworld
License: The text of "PLA vs ABS: Filaments for 3D Printing Explained & Compared" by All3DP is licensed under a Creative Commons Attribution 4.0 International License.