Selective Laser Sintering for Prototype Production

August 22, 2014

In a recent blog post, we discussed the growth in 3D metal printing and its impact on manufacturing. Today, we shift our focus from the industry as a whole to a particular technique that has been instrumental in the production of metal prototypes, as well as plastic, ceramic, and glass materials — even coffee. Selective laser sintering has taken the world of 3D printing by storm.

Coffee Production: From the Inside Out

For many of us, coffee is a crucial step in our morning routine (it’s definitely the case for me). With the hectic nature of most mornings, we rarely take the time to reflect on the roots of a fresh cup of coffee: the beans. Addressing the concerns of harvesters, two graduate students from Stanford University designed a pH probe for measuring fermentation acidity, helping harvesters gain greater control over their beans and the fermentation process. To support practical testing purposes, the students sought to develop prototypes that were both functional and as similar to a production-ready device as possible. For this, the team turned to selective laser sintering in creating the casings and strainer to help protect the sensor itself and provide more accurate readings.

Selective laser sintering to enhance the quality of coffee.
A cup of coffee. Image by Julius Schorzman (Own work) CC-BY-SA-2.0, via Wikimedia Commons.

Now, shift from taste to packaging. As part of a worldwide branding campaign, NESCAFÉ designed reusable caps for their coffee that feature seven different alarm tones. These tones are synchronized with light to create an experience that both awakens people and prompts them to open the cap and make a cup of coffee in order to stop the alarm. This innovative product was created with the help of 3D printing, notably selective laser sintering, and features a nylon finish.

Curiosity sparked? Let’s take a closer look at how this technique works.

The Process of Selective Laser Sintering

In selective laser sintering, a high-powered laser is applied to a powdered material. This material is typically a coated powder or a powder composed of a base material and a compound intended to help with sintering. Working as a power source, the laser sinters the material, following the pattern of each cross section, as defined by a 3D digital description, onto the bed of powder. The powder is traced layer by layer and fused together, with the process repeating itself until the entire part has been constructed. The end result is a structure with a solid 3D shape.

While similar to selective laser melting, it is important to note that selective laser sintering does not bring powders to a full melt. During the sintering process, materials are heated, but not to the point of liquification.

Advantages of This 3D Printing Technique

So, why is selective laser sintering a popular choice in 3D printing?

For one, this process does not require the use of support structures. Because the part is developed from a powder, there is no risk of the design collapsing during the development process. Thus, the freedom within this technique allows for the construction of parts featuring more complex geometries.

In addition to the variety in types of materials that can be used, this method is also valued for its ability to create durable products in a time-efficient manner. Materials made with selective laser sintering require little to no processing once the material has been sintered. By eliminating or reducing this step, the process allows for the development of high-quality prototypes at a more rapid rate.

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