Quality Control Options for AM with Metals

Laser Powder Bed Fusion (L-PBF) makes it possible to build highly complex parts. This additive manufacturing technology is incredibly versatile for many use cases, but successfully manufacturing a part is a multi-step process. Each step is critical in ensuring industrial-grade quality from that initial design to the moment the part is in your hands.

Choosing between a comprehensive set of dimensional, surface, and material property-related inspection reports can be helpful to ensure quality. These provide different levels of insight that might be invaluable to understanding how your part will perform. This guide will explain each choice and when they’re best suited for your part.

These quality control and testing options are available on the MakerVerse platform for parts created with L-PBF. By choosing the right test, you could save a lot of time or money by getting the in-depth insights needed to know that your part meets your standards.

Quality Inspection

This is a standard option included in every order on the MakerVerse platform. Every part – whether made with L-PBF or another technology – is inspected in person by additive manufacturing application engineers. In addition to the visual inspection, the team takes basic dimensional measurements. These experts can determine if there are any immediate issues with the final print – and then work with the suppliers to fix these problems.

When to use this: Always, as it’s included with every order.

CT Scan

A CT (computed tomography) scan provides a detailed look at the part’s internal material properties. The part is placed between an X-ray emitter and an X-ray detector for a CT scan. A tomographic reconstruction is made by emitting X-ray beams from different angles for various layers. This provides a detailed cross-section view of the part in virtual slices.

This scan is performed according to ISO 17025 standards, which “enables laboratories to demonstrate that they operate competently and generate valid results.” Choosing this option includes the CT data for self-analysis (GOM Volume Inspect) and an expert report for an additional charge.

When to Use This: When needing to check the internal material properties of an L-PBF part against potential defects, errors, pores, inclusions, or voids

Learn more about optimizing designs for Laser Powder Bed Fusion with this guide.

Optical Dimensional Measurement (3D Scan)

With this option, you can compare the dimensional properties of the L-PBF part to the original design. It is a common procedure in the additive industry. By default, the best fit method for alignment will be used, but if necessary, your report can be adjusted to a defined reference point.

First, moving fringe patterns are projected onto the part’s surface with a high-power blue light source. High-quality stereo cameras capable of high resolutions capture the reflections from the projection. Ambient non-blue light is filtered out to measure the dimensions of the printed part. When choosing a 3D scan, you’ll receive an inspection report providing false-color pictures from three angles.

When to Use This: When free-form structures or contours need to be quickly measured for accuracy

Tactile CMM Scan

A coordinate measuring machine (CMM) provides exact dimensional measurements of your part. You can see how the printed part compares to your original design with a precision of up to 3μm. Costs and lead times are higher than an optical dimensional measurement, but the scan is more accurate.

In this measurement method, a highly sensitive tactile sensor touches the part’s surface. The sensor measures coordinate data points, sends the data to a computer, and then compares the findings to the original design file. The CMM can determine the slightest deviations between the actual part and the drawing specifications. You’ll receive a report of at least five physically measured points that can be compared to the original file.

When to use this: When you need the highest levels of accuracy in measuring the geometry of your part or when you need to verify specified tolerances

Want to know all about the different post-processing options for L-PBF? This guide has you covered.

Tensile Test

Choosing a tensile test provides important data on the mechanical properties of the printed part, such as maximum stress, yield, elongation, and other properties.

For a tensile test, tensile bars are printed with your order. These bars are then placed in a universal testing machine and pulled until failure. This test is conducted according to ISO 527, the standard for determining the tensile properties of polymers and ISO 6892 for metals. You’ll receive an inspection report with the results from the tensile test with the delivery of your parts.

When to use this: When the mechanical properties of your part are critical to its end use. Or, you want to evaluate the quality of a process or machine involved in creating the part.

Density Test

Testing for density is a quality control measure to ensure the consistency of your part that isn’t possible with a surface-level examination.

For this test, density cubes are printed with your order. These cubes are then measured through a cross-section to determine the exact density. Once measured, you can see how the density compares to the properties of the material you chose to print in. An inspection report with the results from the density test will be submitted with the delivery of the parts.

When to use this: When the mechanical properties of your part are critical to its end use. Or, you need to evaluate a process or machine involved in creating the part.

Surface Roughness Measurement

A part’s surface roughness can affect its durability, friction, and other factors, so achieving an acceptable roughness is essential for industrial use.

A sensitive stylus is dragged along the surface, measuring the heights and valleys with a precision better than .03μm. The measurements are extrapolated to the entire surface, computing roughness metrics. This process is all performed to the DIN ISO 4287 standard. You will receive a report with your part, including the heights and valleys from the up to 50mm path and the computed Rz and Ra values.

When to use this: When the surface roughness is critical to the function of the part