Additive Manufacturing: What is Selective Laser Sintering?

With all the buzz about Additive Manufacturing, or 3D Printing, in the manufacturing world today, there is a lot of mystery and confusion surrounding the common practices and techniques. So, this week’s blog post will address a common type of 3D printing known as Selective Laser Sintering (SLS).

But first, What is Additive Manufacturing?

Additive manufacturing is the process of creating a part by laying down a series of successive cross-sections (a 2D “sliced” section of a part). It came into the manufacturing world about 35 years ago in the early 1980s, and was adapted more widely later in the decade. Another common term used to describe additive manufacturing is 3D Printing. A term which originally referred to a specific process, but is now used to describe all similar technologies.

Now that we’ve covered the basics of 3D Printing, What is Selective Laser Sintering?

It is actually part of a broader category, commonly referred to as a Granular Based Technique. All granular based additive manufacturing techniques start with a bed of a powdered material. A laser beam or bonding agent joins the material in a cross section of the part. Then the platform beneath the bed of material is lowered, and a fresh layer of material is brushed over the top of the cross section. The process is then repeated until a complete part is produced. The first commercialized technique of this category is known as Selective Laser Sintering.

The Selective Laser Sintering Technique was developed in the mid-1980s by Dr. Carl Deckard and Dr. Joseph Beaman and the University of Texas at Austin, under DARPA sponsorship. As a result of this, Deckard and Beaman established the DTM Corporation with the explicit purpose of manufacturing SLS machines.  And, in 2001, DTM was purchased by their largest competitor, 3D systems.

What Are the Advantages of this Process?

SLS is quick. It’s one of the fastest rapid prototyping techniques. Though, relatively speaking, most techniques are fast. SLS also has the widest array of usable materials. Theoretically, just about any powdered material can be used to produce parts. In addition, it can potentially be one of the most accurate rapid prototyping processes – the major limiting factor being the particle size of the powdered material.

Because parts are created in a bed of material, there is no need to use support structures like in other forms of rapid prototyping. This helps to avoid secondary operations and machining. Another advantage of the material bed is the ability to stack multiple parts into the build envelope. This can greatly increase the throughput of a SLS machine.

What Are the Disadvantages of this Process?

Of the commercially available rapid prototyping machines, those that use the Selective Laser Sintering technique tend to have the largest price tag. This is usually due to the scale production these machines are designed for, making them much larger than others.

SLS can be very messy. The material used is a bed of powdered material and, if not properly contained, will get EVERYWHERE. In addition, breathing in powdered metals and polymers can potentially be very hazardous to one’s health; though most machines account for this, it is certainly something to be cognizant of when manufacturing.

Unlike other manufacturing processes, SLS limits each part to a single material. This means parts printed on SLS machines will be limited to those with uniform material properties throughout.

As materials aren’t fully melted, full density parts are not created through this process. Thus, parts will be weaker than those created with traditional manufacturing processes, although full density parts can be created through similar manufacturing processes, such as SLM.

In Conclusion

There are quite a few different ways to 3D print a part, with unique advantages and disadvantages of each process. This post is part of a series, discussing the different techniques. Thanks for reading!

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