What is PLA (polylactic acid) filament?

A brief history of PLA 

This section outlines how PLA is produced, its origins, and its applications in manufacturing and FDM 3D printing.

How is PLA made?

PLA is produced by fermenting sugars from plant-based feedstocks such as corn starch or sugarcane to generate lactic acid, which is then converted to lactide and polymerized. The resulting resin is supplied as granulated pellets for manufacturing processes such as injection molding and casting, or extruded into filament, spooled, and supplied for additive manufacturing.

Early uses of PLA 3D

PLA was developed in the 1930s but did not see wide use until the 1980s. Its adoption in 3D printing grew after that due to ease of use and relatively low cost.

What is PLA used for now?

PLA is used across many industries for a wide range of applications, including:

• Food and beverage: Because it is derived from natural sources, PLA is non-toxic and food safe. It is used to package items intended for human consumption.

• Medical: PLA’s non-toxicity allows use in parts such as binding screws and other implantable devices.

• Textiles: PLA is breathable and lightweight, making it a good choice for textiles.

• Cosmetics: PLA is relatively affordable and environmentally friendly, and is increasingly used for cosmetics packaging for both cost and environmental reasons.

• Prototyping: Especially when 3D printed, PLA is a strong option for prototyping where speed, cost and ease of use are priorities.

How PLA works

This section reviews PLA types, typical pricing, and material properties.

What are the types of PLA?

 There are three main types of PLA: PDLA, PLLA and PDLLA. Here are the key properties of each.

• PDLA (poly-D-lactic acid): Biodegrades more slowly than other PLA types.

• PLLA (poly-L-lactic acid): Most commonly used for 3D printing and injection molding. PLA+ is typically PLLA with strength-enhancing additives.

• PDLLA (poly-DL-lactic acid): Breaks down more quickly than other PLA types, making it suitable for pharmaceutical applications intended for ingestion.

PLA is available in many colors and surface finishes, including matte, glossy and silk. It is also supplied in hybrid grades that combine PLA with materials such as wood, or with additives that increase strength or flexibility.

How does pricing for PLA 3D printing filament work?

PLA filament pricing varies by color, brand and material characteristics. Hybrid filaments that combine PLA with materials such as wood, or include additives to increase strength or flexibility, typically cost more than standard PLA. Most PLA 3D printing filament is priced between €20-70 per kilogram.

Is PLA a sustainable material?

PLA is bio-based and more environmentally friendly than many petroleum-based plastics. It is biodegradable, compostable and recyclable.

What are the main properties of PLA?

PLA has several key properties:

• High stiffness: PLA is stiff and relatively brittle with low flexibility.

• Good strength: Flexural strength around 103 MPa.

• Low melting point: Approximately 145 °C, suitable for 3D printing.

• Good aesthetic properties: Produces smooth surfaces and fine detail.

• Low UV and temperature resistance: Deforms under elevated heat and UV exposure.

• Chemical resistance: Not soluble in acetone or isopropyl alcohol; some chemicals can cause it to release lactic acid.

• Dimensional stability: Low warping helps produce large parts close to CAD dimensions.

Designing parts with PLA

This section covers best practices for 3D printing with PLA and common post-processing techniques for the material.

What are best practices for PLA?

Consider these guidelines when designing or 3D printing PLA parts to improve quality and consistency.

• Oozing: Because of its low melting point, PLA can leak from the nozzle. Increase retraction distance and speed to reduce oozing.

• Cooling: PLA stays soft for longer, so effective cooling is essential. Keep the part cooling fan at full power during printing to solidify layers.

• Heated print bed: A heated bed is not required, but it can be used to tune first-layer adhesion. Adjust bed temperature to increase or decrease adhesion as needed.

• Nozzle temperature: Match nozzle temperature to the PLA grade to prevent stringing and surface defects, typically 190 to 230 °C.

What post-processing techniques do you use for PLA 3D printing material?

 PLA parts can be post-processed in several ways:

• Support removal: PLA is often printed with PVA (polyvinyl alcohol) support for overhangs. After printing, the part is submerged in water to dissolve the PVA support, since PVA is water soluble.

• Sanding: Surfaces can be sanded to smooth layer lines and refine local features.

• Polishing: Parts can be buffed to achieve a smooth, uniform surface.

• Painting: Although PLA filament is available in many colors, parts may be painted to meet application-specific color and finish requirements.

Want to learn more about 3D printing? Read our full guide, What is 3D printing?, or check out our article, How to design parts for FDM 3D printing.

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When you’re ready to start 3D printing, upload your CAD file for an instant quote and automated DFM analysis. For questions or specific requests, contact networksales@protolabs.com .