Why Additive Manufacturing Requires a Different Approach to Mechanical Testing
From prototyping to production: What changes when additive manufacturing scales
Additive manufacturing, more commonly known as 3D printing, has evolved far beyond its early role as a rapid prototyping tool. Today, it is increasingly used for the serial production of functional, load-bearing components across a wide range of industries. As adoption accelerates, so too does the need for repeatable and accurate mechanical testing to ensure performance, reliability, and regulatory confidence.
This series of blog posts explores the fundamentals of additive manufacturing, the unique testing challenges associated with additively manufactured parts, and how the right testing approach, and the right testing partner, enables engineers to confidently move additive manufacturing from development into production.
What Is Additive Manufacturing?
Additive manufacturing is the process of creating objects by adding material layer by layer directly from a digital model. This approach contrasts with traditional subtractive manufacturing, where material is removed from a solid block through machining.
This layer-by-layer method unlocks several significant advantages. Additive manufacturing provides unparalleled design freedom, enabling complex internal features, lattice structures, and geometries that would be impractical or impossible to machine. It also supports rapid iteration, dramatically shortening development cycles from concept to physical part. Additionally, additive manufacturing can be highly cost-effective for low- to medium-volume production due to minimal tooling requirements, while also reducing material waste. These benefits make additive manufacturing particularly attractive for customized, on-demand production.
However, these same advantages introduce new variables that must be understood, measured, and controlled through high-quality testing.
Key Additive Manufacturing Technologies
A wide range of additive technologies are now used across industrial applications, each with its own material behaviors and testing requirements.
Fused deposition modeling (FDM) is one of the most widely recognized additive manufacturing processes. It works by melting and extruding a filament through a nozzle, typically using thermoplastics. While historically limited to polymers, FDM is now also available for metals and fiber‑reinforced composites.
Directed energy deposition (DED) is a process in which focused energy melts material as it is deposited, with wire arc additive manufacturing (WAAM) being a high deposition rate DED variant that is effectively a controlled welding process. WAAM is particularly well suited for producing large metal components and offers a more cost-effective solution for large-scale metal builds.
Powder bed fusion technologies use a heat source to fuse powdered material layer by layer, including:
- Selective laser melting (SLM) for high‑density metal parts
- Selective laser sintering (SLS) for polymer components
- Electron beam melting (EBM) for reactive metals such as titanium
- Direct metal laser sintering (DMLS) for precision metal applications
Other processes such as binder jetting and stereolithography (SLA) continue to expand the additive manufacturing landscape, further increasing the diversity of materials and test requirements that engineers must manage.
Market Trends and Growth
Additive manufacturing is now used across metals, polymers, ceramics, and composites, with adoption spanning aerospace, automotive, biomedical, electronics, construction, tooling, and consumer goods. The global market is currently valued at tens of billions of dollars and is forecast to grow rapidly over the coming decade.
Key areas of growth include new and optimized materials such as novel metal alloys and sustainable materials, multi-material printing for parts with spatially varying properties, and AI-driven design, process, and quality optimization.
As additive manufacturing becomes a core manufacturing route for structural and safety-critical parts, mechanical testing of additively manufactured parts is being seen more frequently not just for research and qualification but also for validation and certification.
Challenges in Additive Manufacturing
When considering the mechanical properties of additively manufactured parts, several technical challenges directly impact mechanical performance.
Additively manufactured parts frequently exhibit defects such as porosity, lack of fusion, and surface roughness, which can lead to mechanical weakness. These arise because parts are effectively composed of thousands of small, incremental “casts,” each introducing potential imperfections. Post-processing techniques like machining and heat treatment can reduce these issues, but they cannot eliminate them entirely.
Another major challenge is increased variability in material properties. Variations within a single part, referred to as inhomogeneity, can occur due to differences in heat dissipation along the print paths. Additionally, variability can occur part to part, operator to operator, machine to machine, and with process and production parameters. This variability can impact the sample size required for confident data.
Finally, additively manufactured components often display highly directional properties, known as anisotropy. Because parts are built layer by layer, mechanical properties in the build (Z) direction are typically weaker than those in the XY plane. This directional behavior has important implications for accurate alignment, control, and repeatability during testing.
The Instron Approach: Accurate and Reliable Testing
With additive manufacturing introducing higher variability, greater data scatter, and strong directional behavior, the quality of the test system matters as much as the material itself. Rigorous mechanical testing is essential to distinguish true material behavior from test-induced effects.
Instron® testing systems are designed to deliver the precision, stability, and repeatability required for additively manufactured materials from early material screening to full qualification testing. By combining accurate load and strain measurement with application-specific fixturing and expert support, Instron enables engineers to generate reliable data they can trust.
In a manufacturing landscape where performance is defined by defects, variability, and anisotropy, partnering with a testing leader like Instron is essential for turning innovative designs into dependable, production-ready components.
About the Author
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Rebecca Reiff-Musgrove
Rebecca Reiff-Musgrove is Business Development Manager for ElectroPuls® at Instron. Her background includes an MSci from the University of Cambridge with a focus on the surface properties of additively manufactured parts, as well as previous roles in materials testing for the additive manufacturing industry. At Instron, she has held a range of technical and commercial roles, giving her a grounded understanding of both the technology and the customer challenges it addresses.