Optimizing 3D printing: The Role of Nitrogen in the SLS Process

In the dynamic world of additive manufacturing, Selective Laser Sintering (SLS) enables the production of complex, high-performance components from powdered materials. One critical aspect of the SLS process is the role of the environment in which sintering occurs. Among the various factors, the protective gas atmosphere highly influences achieving optimal results. Although there’s some kind of awareness among the people I talk to of the necessity of using the gas during the SLS printing process, ‘the rest’ of it remains a question mark sometimes. Let’s find out how the management of nitrogen in SLS works in practice.

Table of Contents

• How Nitrogen Enhances the SLS Process? 

The role of nitrogen in controlling oxidation and improving material integrity.

• Material Compatibility with Nitrogen Printing

Examining which polymers and powders benefit most from nitrogen-based environments.

• Nitrogen Bottle vs. Nitrogen Generator: What to Choose for Lisa X?

Comparing the benefits and limitations of using nitrogen bottles versus nitrogen generators, helping you decide which option best suits your printing needs.

• Printing with Nitrogen on Lisa X

Explaing how using nitrogen enhances print quality also providing specific numbers related to nitrogen supply requirements.

• Conclusions on the Role of Inert Gas Atmosphere in SLS Printing Process

Summarizes the importance of an inert gas atmosphere in the SLS printing in the form of shot  Q&A.

How Does Nitrogen Enhance the SLS Printing? 

Nitrogen plays a pivotal role in protecting sensitive materials from oxidation, enhancing part quality, and ensuring consistency in production. 

The SLS process involves the use of high-powered lasers to selectively fuse particles of powdered material. This intense heating makes the material susceptible to oxidation and thermal degradation if not protected. Nitrogen, being an inert gas, provides a controlled atmosphere that minimizes these risks.

By eliminating or reducing the presence of oxygen, nitrogen helps maintain the chemical stability of the material throughout the printing process. This ensures uniform sintering, improves mechanical properties, and consistent performance in printed parts, especially when working with polymers like polyamides or thermoplastic elastomers.

Material Compatibility with Nitrogen Printing

When working with SLS, it’s important to note that not all materials behave the same way, and nitrogen is only required for select materials to achieve optimal results.

I know that I will possibly need to print with nitrogen, but does the material I intend to use need it? Should I provide a nitrogen supply for printing models for my application? 

These are frequently asked questions, especially by those who start the journey with SLS.  

Understanding which materials are compatible with nitrogen is crucial not only for ensuring high-quality results but also for improving process efficiency, minimizing waste, and accurately preparing for associated costs.

So- finally:

How do I know if I should use nitrogen for my models printed in SLS? Which materials require an inert gas atmosphere for printing?

Oxidation sensitivity of the material is important. Materials prone to oxidation at high temperatures, such as certain nylons, typically require a nitrogen atmosphere to prevent degradation during the sintering process.

But to avoid delving into chemistry I would just simply ask the manufacturer about the above—straightforward answers are the best. 

Sinterit suggests using nitrogen when printing with PA11 materials on Lisa X to keep oxidation low and get the best mechanical properties and surface quality. With a wide range of PA11 options in the portfolio, Sinterit offers materials that work great for different applications, especially when paired with nitrogen for even better results.

Nitrogen Bottle vs. Nitrogen Generator: What to Choose for Lisa X?

When I talk to those interested in implementing SLS 3D printing in-house, one question that often comes up is whether they should choose a nitrogen bottle or a nitrogen generator for their setup. It’s a valid question, and the answer depends on a few factors. Here’s a quick summary I’ve prepared to help you make the right choice.

Nitrogen Bottle:

Advantages:

• Readily available and easy to use, making it ideal for smaller or occasional print jobs.
• Lower initial investment compared to a nitrogen generator.
• No installation or setup is required.

Disadvantages:

• Requires regular replacements, which can disrupt long production cycles.
• Downtime for refills can interrupt workflow.
• Less cost-effective for high-volume or long-term operations.

A typical 20L bottle with 300bar (5.3m³) lasts around 10 hours, while a 40L bottle with 150bar (6m³) lasts about 11 hours.

Nitrogen Generator:

Advantages:

• Provides a continuous, reliable supply of nitrogen, eliminating the need for frequent replacements.
• Cost-effective in the long run for high-volume or long-duration printing.
• Eliminates downtime for refills, ensuring consistent production.

Disadvantages:

• Higher initial cost compared to nitrogen bottles.
• Requires proper installation and maintenance.

Once set up, it meets the flow rate requirements of 10 l/min at 5 bar pressure and maintains a purity level of 99.5%.

To quickly sum up: For small-scale or occasional printing, nitrogen bottles are often sufficient. However, for consistent, large-scale production or frequent long-duration prints, a nitrogen generator is the better choice due to its efficiency, reduced downtime, and long-term cost-effectiveness.Ultimately, the best option depends on your workload, budget, and long-term printing needs.

Printing with Nitrogen on Lisa X

Printing with nitrogen on the Lisa X delivers top-quality results by keeping the environment controlled, reducing oxidation, and preserving material integrity during sintering. Here’s a simple guide I’ve prepared  to help you plan your nitrogen usage with Lisa X printer:

• Nitrogen Consumption Rate: The Lisa X consumes approximately 0.51 m³/h (8.5 l/min). For a 24-hour print job, you’ll need an estimated 12.24 m³ of nitrogen, assuming ideal conditions without losses. To account for potential variations, it’s recommended to use a nitrogen tank with extra reserve capacity.
• Planning Nitrogen Usage: You can check the estimated print time in the “Slice” tab of Sinterit Studio after slicing your project. The report window will also show the required nitrogen amount.
• Tank Estimates:
  • A 20L, 5.3m³, 300 bar nitrogen tank lasts about 10 hours of printing.
  • A 40L, 6m³, 150bar tank lasts around 11 hours under ideal conditions.
• Purity and Pressure: Ensure the nitrogen purity is at least 99.5% and the tank’s pressure reduction valve is set between 5-6 bars.
• Using a Nitrogen Generator: If you’re using a nitrogen generator, confirm it can maintain a flow rate of at least 10 l/min while meeting the required purity and pressure levels.

Now you can see that when planning for nitrogen use in SLS printing, it’s important to account for specific parameters such as flow rate, pressure, and consumption per print cycle, as these factors directly impact the efficiency and quality of the printing process.

Conclusions on the role of inter gas atmosphere in SLS printing proces

To make things clearer, I decided to present a summary in the form of a Q & A – it provides a straightforward and engaging way to address common questions.

What’s the role of nitrogen in SLS 3D printing?

Nitrogen prevents oxidation and thermal degradation during the sintering process, ensuring better part quality, dimensional accuracy, and material integrity.  Effectively managing nitrogen ensures smooth operation and keeps your prints on the Lisa X high-quality and precise.

For which materials is it recommended to use a nitrogen supply during SLS printing process?

Sinterit  recommends using a nitrogen supply for printing with PA11 materials -PA11 Carbon Fiber, PA11 ESD, and PA11 Onyx.

What to choose for SLS printing process : nitrogen tank or nitrogen generator? 

If you run a business with low print volumes, nitrogen bottles might be a more practical and budget-friendly option. But if you’re looking to scale up and streamline your printing process, a nitrogen generator is a smarter long-term investment, providing continuous operation and added convenience.

When writing this summary I was looking for a golden thought I could place in the end. Taking the opportunity, I’d like to pay tribute to my colleague – she knows.

All PA11 prints made with the use of nitrogen enjoy enhanced durability and superior quality, and in the end, these printouts live happily ever after in their intended applications.

Author: Monika Jurek

SLS 3D Customer-Centric Associate with two years of experience working with companies worldwide. She specializes in helping businesses identify optimal solutions for implementing 3D printing using SLS technology.