Metal 3D printing has been around for roughly 30 years, yet the technology can still turn heads. At trade shows, for instance, the printed metal parts we have on display at our booth often elicit surprise from those stopping by for a closer look, slightly stunned that parts can, in fact, be 3D printed from metal.

We use direct metal laser sintering (DMLS), an industrial-grade, metal 3D printing technology that builds fully functional metal prototypes and end-use production parts from a range of materials, including stainless steel (17-4 PH and 316L), aluminum (AlSi10Mg), Inconel 718, cobalt chrome (Co28Cr6Mo), and titanium. Metal 3D printing is commonly used for:

• Prototyping in production-grade materials
• Creating custom parts that require complex geometries
• Building functional end-use parts
• Reducing the number of metal components in an assembly

Within the context of metal 3D printing materials, a part's density is an especially key physical property for both engineers and product designers. In engineering, density may refer to one of two separate but related concepts: Bulk density is expressed in grams per cubic centimeter, and porosity is expressed as a percentage of fill. We cover both in this article.

Let's take a look at both factors, but first some brief background on DMLS.

DMLS starts with a metal powder that is melted in layers to form the part.