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
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 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.
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